Bài giảng NET programming 2014 Nguyễn Đạt Thông: Tổng hợp kiến thức

2/19/2014

Nội dung

1. Tổng quan về .NET framework và MS Visual Studio .NET

2. Tổng quan về C#

Nguyen Dat Thong Faculty of Mathematics and Informatics University of Science, VNU-HCM

3. Lập trình Windows Forms

4. Đa luồng và kết nối mạng

5. Kết nối cơ sở dữ liệu

6. Windows Presentation Foundations và Silverlight

.NET Programming - Nguyễn Đạt Thông 2

Tổng quan về .NET Framework

(cid:1) .NET Framework là gì?

(cid:1) Common Language Runtime

Chương 1

(cid:1) Base Class Library

(cid:1) Common Language Infrastructure

(cid:1) Assembly

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.NET Framework là gì?

Mục tiêu của .NET Framework

(cid:1) The .NET Framework is a technology that supports building and

(cid:1) To provide

running the next generation of applications and XML Web services.

(cid:2) a consistent object-oriented programming environment .

(cid:2) a code-execution environment that minimizes software deployment and

(cid:1) The .NET Framework is a managed execution environment that

versioning conflicts.

provides a variety of services to its running applications.

(cid:2) a code-execution environment that promotes safe execution of code, including

code created by an unknown or semi-trusted third party.

(cid:2) a code-execution environment that eliminates the performance problems of

scripted or interpreted environments.

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Mục tiêu của .NET Framework

Các dịch vụ của .NET Framework

(cid:1) To make the developer experience consistent across widely varying

(cid:1) Memory management.

(cid:1) Language interoperability.

types of applications, (cid:2) such as Windows-based applications and Web-based applications.

(cid:1) A common type system.

(cid:1) Version compatibility.

(cid:1) To build all communication on industry standards

(cid:1) An extensive class library.

(cid:1) Side-by-side execution.

(cid:2) to ensure that code based on the .NET Framework can integrate with any other

code.

(cid:1) Development frameworks

(cid:1) Multi-targeting.

and technologies.

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Kiến trúc .NET Framework

Common Language Runtime (CLR)

(cid:1) .NET Framework consists of two major components:

(cid:1) The common language runtime (CLR) manages

(cid:2) memory, thread execution, code execution, code safety verification, compilation,

and other system services.

(cid:2) the common language runtime (CLR) (cid:2) the .NET Framework Class Library

(cid:1) All programs by any language which has written for the .NET

framework are executed by the CLR (cid:2) and it is common to all versions of the .NET.

(cid:1) The runtime enforces code access security.

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Các thành phần của CLR

Common Type System (CTS)

CTS

VB .NET C#

C++

(cid:1) Common Type System (CTS)

(cid:1) Intermediate Language (IL)

(cid:1) Just-In-Time (JIT) Compiler

byte sbyte short int long ushort

(cid:1) Garbage Collector (GC)

System.Byte System.SByte System.Int16 System.Int32 System.Int64 System.UInt16 System.UInt32 System.UInt64 System.Single System.Double System.Object System.Char System.String System.Decimal System.Boolean

Byte SByte Short Integer Long UShort UInteger uint ULong Single Double Object Char String Decimal Boolean

unsigned char unsigned char short int or long __int64 unsigned short unsigned int or unsigned long unsigned __int64 ulong float float double double object^ object wchar_t char String^ string decimal Decimal bool

bool

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Intermediate Language (IL)

Just-In-Time (JIT) Compiler

(cid:1) Intermediate Language (IL) is a CPU-independent set of instructions.

(cid:1) JIT Compiler is a component inside the “runtime” which performs

compilation.

(cid:1) IL is not byte-code, but is very close to it.

(cid:2) Therefore, when the application is executed, the IL to machine code conversion

(cid:1) The process of compiling IL code into machine code takes some

is quick.

time, (cid:2) but for each part of a program, it generally means only one-time compile per

process.

(cid:1) IL converted to CPU-specific code by Just-In-Time Compiler of

Common Language Runtime (CLR)

(cid:1) Once the code is compiled, the CLR holds it and executes the

compiled version the next time it’s needed.

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Garbage Collector (GC)

Các ứng dụng .NET

(cid:1) Garbage Collection

(cid:2) is the process of automatically de-allocating memory based on the program’s

C# Code

C# Compiler

needs.

(cid:1) GC’s purpose is to restore memory consumed by objects that are no

longer referenced.

Visual Basic Code

Visual Basic Compiler

JIT Compiler (CLR)

(cid:1) GC does not handle other resources such as

COBOL Code

COBOL Compiler

(cid:2) database connections, (cid:2) handles (files, windows, and so on), (cid:2) network ports, (cid:2) and hardware devices such as serial ports.

Native Code

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Base Class Library

Standardized

Non-standardized

(cid:1) Base Class Library (BCL) is a core set of CLR class libraries

(cid:2) that programs may utilize (cid:2) and it is available for all CLR languages.

(cid:1) Framework Class Library (FCL) that adds some features to BCL. It

includes support for (cid:2) Client UI, (cid:2) web UI, (cid:2) database access, (cid:2) distributed communication, (cid:2) and other libraries.

System System.Collections System.Diagnostics System.Globalization System.IO System.Net System.Reflection System.Runtime System.Security System.Text System.Threading System.Xml System.Diagnostics.CodeAnalysis System.Diagnostics.Contracts System.Diagnostics.Eventing System.Diagnostics.PerformanceData System.Diagnostics.SymbolStore

System.CodeDom System.ComponentModel System.Configuration System.Data System.Deployment System.DirectoryServices System.Drawing System.EnterpriseServices System.Linq System.Linq.Expressions System.Management System.Media System.Messaging System.Resources System.ServiceProcess System.Timers System.Transactions System.Web System.Windows.Forms

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Common Language Infrastructure (CLI)

CLI

(cid:1) The Common Language Infrastructure (CLI)

(cid:1) The (CLR) is Microsoft's implementation of the CLI standard and is

responsible for managing the execution of .NET programs.

(cid:2) is an open specification that describes the executable code and runtime

environment.

Implementation

Description

Microsoft .NET framework

Premier compiler which limited to run on the Windows.

(cid:1) It developed by Microsoft and standardized by ISO and ECMA.

Microsoft Silverlight

CLI Cross-platform implementation that runs on both the Windows family and the Macintosh.

Microsoft Compact Framework

Light-weight implementation of the .NET Framework designed to run on PDAs and phones.

(cid:1) It forms the core of the Microsoft .NET and other CLI

Microsoft XNA

Implementation for Xbox and Windows game developers.

implementations.

Mono Project

Open source implementation designed to provide Windows, Linux, and Unix compatible version of the CLI.

DotGNU

Focused on platform-portable applications that can run both the .NET and the DotGNU. Supports GNU/Linux BSD, Cygwin/Mingw32, Mac OS X, Solaris, AIX, and PARISC.

Rotor

Also known as the Shared Source CLI. It’s CLI implementation that Microsoft developed to run on Windows, Mac OS X, and FreeBSD for educational purposes.

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Assembly

(cid:1) According to CLI specification, assembly is the CLI output after

(cid:1) An assembly can contain more than one code module which has

code’s compilation.

used several different languages. (cid:2) Not support by Microsoft Visual Studio

(cid:1) Assemblies can be

(cid:1) Assemblies form the logical construct of a component or unit of

deployment.

(cid:2) library assemblies (DLL – Class Libraries) or (cid:2) process assemblies (EXE - Executables).

(cid:1) Although an assembly can include multiple files, there is only one

(cid:1) An assembly can reference other assemblies and files

version number.

(cid:2) such as resource files that have been localized.

(cid:1) Microsoft has provided “ILMerge.exe” utility for combining multiple

(cid:1) An assembly can consist of one or more files.

modules and their manifests into a single file assembly.

(cid:2) Code files are called modules.

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Assembly

(cid:1) The files consisted in an assembly can include compiled modules,

(cid:1) Assemblies are either strongly named or not strongly named.

resources, and any other components listed in the assembly manifest.

(cid:1) A strongly named assembly has a hash code built into its manifest

(cid:2) that the loader can use to test the integrity of the assembly to ensure it has not

been modified.

(cid:1) The assembly manifest is typically included in the main assembly module and contains essential identification information, including which pieces belong to the assembly.

(cid:1) Assemblies can also be digitally signed in order to identify their

producer.

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Ghi chú

Tổng quan về MS Visual Studio .NET

(cid:1) Visual Studio .NET

(cid:1) Solution, Project, and Configuration

(cid:1) Build and Clean

(cid:1) Breakpoint

(cid:1) Debugging

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

(cid:1) MSDN

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Visual Studio .NET

(cid:1) Microsoft Visual Studio is an integrated development environment

(IDE) from Microsoft.

(cid:1) It is used to develop in both (cid:2) native code together with (cid:2) managed code

(cid:1) It is used to develop console and graphical user interface

(cid:1) It is used to develop for all platforms supported by

applications along with (cid:2) Windows Forms applications, (cid:2) web sites, (cid:2) web applications, (cid:2) and web services

(cid:2) Microsoft Windows, (cid:2) Windows Mobile, (cid:2) Windows CE, (cid:2) .NET Framework, (cid:2) .NET Compact Framework and (cid:2) Microsoft Silverlight.

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Tính năng của Visual Studio .NET

Trình soạn thảo

(cid:1) Code Editor (cid:2) IntelliSense (cid:2) Code Refactoring

(cid:1) Debugger

(cid:1) Designer

(cid:2) forms designer, (cid:2) web designer, (cid:2) class designer, (cid:2) and database schema designer

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Debugger

Designer

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Solution

Solution và Project

(cid:1) Visual Studio stores the definition for a solution in two files

(cid:1) A solution is a grouping of

(cid:2) one or more projects that work together to create an application.

(cid:2) .sln and .suo

(cid:1) Projects are used in a solution to

(cid:1) The solution definition file (.sln) stores

(cid:2) logically manage, build, and debug the items that make up your application.

(cid:2) Projects that are associated with the solution. (cid:2) Solution build configurations.

(cid:1) The solution user options file (.sou) stores

(cid:2) metadata which is used to customize the IDE whenever the solution is active.

(cid:1) The output of a project is usually (cid:2) an executable program (.exe), (cid:2) a dynamic-link library (.dll) file or (cid:2) a module, among others.

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Tạo một Solution mới

Solution Files

(cid:1) On the File menu, click New and then click New Project.

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Công cụ Solution Explorer

Project

(cid:1) Solution Explorer provides

(cid:1) Visual Studio provides several pre-defined project templates.

(cid:2) an organized view of projects and their files (cid:2) as well as ready access to the commands that pertain to them.

(cid:1) These templates are used to

(cid:2) develop an application, a class, a control, or a library.

(cid:1) To access Solution Explorer,

(cid:2) select Solution Explorer on the View menu

(cid:1) The default templates in Visual Studio include

(cid:2) Visual Basic projects (cid:2) Visual C# projects (cid:2) Visual C++ projects

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Tạo một Project mới

Một số Templates thông dụng

Template

More Information

(cid:1) On the File menu, click New and then click New Project.

Empty Project

The Empty Project template can be used when user wants to create his own project type

Class Library

Use the Class Library template to quickly create reusable classes and components that can be shared with other projects

Console Application

Console applications are typically designed without a graphical user interface (GUI) and are compiled into an executable file.

Windows Forms Application

This creates a traditional standalone Windows application or a rich front-end to a distributed Web application.

Windows Forms Control Library

The Windows Control Library project template is used to create custom controls to use on Windows Forms

Creates a new Web application.

ASP.NET Web Application

…

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Các thành phần của Project

Thêm “Reference” vào Project

(cid:1) Properties

(cid:1) Select the project, and

(cid:2) open “Add Reference…” from Project menu.

(cid:1) References

(cid:1) Source Files

(cid:1) Reference can be (cid:2) .NET libraries (cid:2) COM (cid:2) Projects in Solution (cid:2) Other libraries

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Thêm thành phần vào Project

Configuration

(cid:1) Select the project, and

(cid:1) Solution build configurations

(cid:2) open “Add New Item…” from Project menu.

(cid:2) let you select which projects to include in different builds of a project or solution.

(cid:1) Project configurations include

(cid:2) detailed build and debug settings for each combination of solution build

configuration and platform.

(cid:1) To change configurations,

(cid:2) open Configuration Manager from Build menu.

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Configuration Manager

Build và Clean

(cid:1) To build a project or entire solution, (cid:2) select “Build XXX” from Build menu.

(cid:1) To clean project or entire solution, (cid:2) select “Clean XXX” from Build menu.

(cid:1) To rebuild (clean and build again) a project or entire solution,

(cid:2) select “Rebuild XXX” from Build menu.

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Errors và Warnings

Start và Debug

(cid:1) Building a project or entire solution could raise errors and warnings.

(cid:1) Once projects are built successfully, Visual Studio can start running “StartUp Project” and debugging all projects within the solution.

(cid:1) Visual Studio helps to point out

(cid:2) where they occurs and gives their causes.

(cid:1) Projects should be built in “Debug” mode.

(cid:1) To start debugging,

(cid:2) choose an executable project (cid:2) Select “Set as StartUp Project” (cid:2) Select “Start new instance” from “Debug”.

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Breakpoints

Đặt breakpoint

(cid:1) Breakpoints are points that break the debugging application.

(cid:1) The debugging application will be broken

(cid:1) To set a breakpoint (cid:2) Open the source file (cid:2) Move to code line to be broken (cid:2) Select “Toggle Breakpoint” from “Debug” menu.

(cid:2) as soon as it meets a “breakpoint”.

(cid:1) To remove a breakpoint (cid:2) Move cursor to that point (cid:2) Select “Toggle Breakpoint” again

(cid:1) To remove or disable all breakpoints (cid:2) Select “Delete All Breakpoints” or (cid:2) Select “Disable All Breakpoints”

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Thay đổi thuộc tính của breakpoint

Thuộc tính của breakpoint

(cid:1) Location

(cid:1) Select an existing breakpoint to change it properties

(cid:2) Where breakpoint is set

(cid:1) Condition

(cid:2) When need to break

(cid:1) Hit Count

(cid:2) Ignore some hits before break

(cid:1) Filter

(cid:2) Break on specific processes and threads

(cid:1) When Hit

(cid:2) Specific what to do when breakpoint is hit

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Tùy chỉnh breakpoint

Debugging

(cid:1) Once the application is broken at a breakpoint,

(cid:2) Visual Studio provides current state and information that helps programmers to

debug the program.

(cid:1) The information include

(cid:2) States of threads (cid:2) Values of variables (cid:2) Call Stack

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Debugging Step–by–Step

Step–by–Step

(cid:1) Once the application is broken at a breakpoint,

(cid:2) Visual Studio provides step–by–step running mechanism that helps

Step Over

programmers find the problems.

(cid:2) Step Over

○ Execute current statement and move to next one

Step Into

Step Out

(cid:2) Step Into

○ If current statement is a call to a procedure, the next statement displayed is the first

statement in the procedure

Step Over

(cid:2) Step Out

○ Executes the remaining lines of a function in which the current execution point lies.

(cid:2) Continue

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MSDN

MSDN Links

(cid:1) MSDN is a reference for all Microsoft developers.

(cid:1) MSDN

http://msdn.microsoft.com/en-US/

(cid:1) It provides information about all Microsoft classes, structures and

(cid:1) MSDN Library

functions.

http://msdn.microsoft.com/library/default.aspx

(cid:1) It also provides sample code and technical articles.

(cid:1) MSDN .NET Development

http://msdn.microsoft.com/en-us/library/ff361664.aspx

(cid:1) MSDN could be used offline and integrated with Microsoft Visual

Studio.

(cid:1) MSDN .NET Class Library

http://msdn.microsoft.com/en-us/library/ms229335(v=vs.90).aspx

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MSDN Web

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MSDN Web

MSDN trong Visual Studio

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Cài đặt MSDN

Thiết lập cấu hình MSDN

(cid:1) Select “Tool >> Options >> Environment >> Help” (cid:1) Select “Integrated Help Viewer”

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Tóm lược

Ghi chú

(cid:1) How to create a solution and projects?

(cid:1) How to add new items to a project?

(cid:1) How to build and debug a program?

(cid:1) How to set and customize breakpoints?

(cid:1) How to step–by–step debug?

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Tổng quan C#

Chương 2

(cid:1) C# Overview (cid:1) First program: Hello C# (cid:1) Statements and Expressions (cid:1) Controlling program (cid:1) Variables (cid:1) Data types (cid:1) Value Types (cid:1) Reference Types (cid:1) Type Conversion (cid:1) Console Input/Ouput

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Tổng quan về C#

Đặc trưng của C#

(cid:1) C# is developed by Anders Hejlsberg and Scott Wiltamuth

(cid:1) C# is a completely Object-Oriented Language.

(cid:2) at Microsoft Corporation.

(cid:1) In C#, every program is class.

(cid:1) C# language is similar to C++

(cid:2) because it is developed from C++ and Java.

(cid:1) In C#, every work is done through objects.

(cid:1) C# is added many new features allowing programmers

(cid:2) to program easier and friendlier.

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Tính năng tiêu biểu của C#

Ngôn ngữ C#

(cid:1) Provides native support for COM (Component Object Model)

(cid:1) C# source code compiles into managed code

(cid:2) an intermediate language (IL).

(cid:1) Manages memory allocation and de-allocation automatically

(cid:2) by Garbage Collector of CLR.

(cid:1) At runtime, the Common Language Runtime (CLR) compiles the

code by using Just In Time (JIT) compiling.

(cid:1) Allows restricted use of native pointers.

(cid:1) The JIT compiler compiles a function or method only the first time (cid:2) and it produces machine code native to the platform on which it’s running.

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Các tính năng mới

Chương trình đầu tiên

(cid:1) 2.0

(cid:1) Hello C#

(cid:2) Generics, Iterators, Partial types, Anonymous method, Static classes, Property

accessibility control, etc.

(cid:2) Console application (cid:2) Print out “Hello C#”

(cid:1) 3.0

(cid:1) How to create

(cid:2) Create a solution and a “Console application” project named “FirstProgram” (cid:2) Open “Program.cs” source file and add following statements to the “Main”

(cid:2) Implicitly Typed Local Variables, Object and Collection Initializers, Extension Methods, Partial Methods, Anonymous Types, Query Keywords, Lambda Expressions, etc.

function

(cid:1) 4.0

Console.WriteLine("Hello C#"); Console.ReadLine();

(cid:2) Named and Optional Parameters, Dynamic Support, Generic Variance, COM

Interoperability.

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Hàm main

Thực thi

(cid:1) The Main method is the entry point of an .exe program;

(cid:1) Set “FirstProgram” as StartUp project

(cid:2) it is where the program control starts and ends.

(cid:1) Build and Run it

(cid:1) Main is declared inside a class or struct.

using System; using System.Collections.Generic; using System.Linq; using System.Text;

(cid:1) Main must be static and it should not be public.

namespace FirstProgram { class Program {

static void Main(string[] args) {

Console.WriteLine("Hello C#"); Console.ReadLine();

(cid:2) Type: static (cid:2) Return type: void or int (cid:2) Parameters: none or string[]

}

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Hàm main: Ví dụ

Chương trình thứ hai

(cid:1) Return type is int

(cid:1) Change Main function to

static void Main(string[] args) {

static int Main() { // do something return 0;

Console.WriteLine("Hello {0} from C#", args[0]); Console.ReadLine();

}

(cid:1) Add command line arguments for debugging

(cid:1) Manipulate arguments

static void Main(string[] args) {

// Display the number of command line arguments // args DO NOT contains the name of the program System.Console.WriteLine(args.Length);

}

(cid:2) Select project “FirstProgram”, (cid:2) Open “FirstProgram Properties…” from Project menu, (cid:2) Open “Debug” tab in Properties page (cid:2) Add “World” to “Command line arguments”

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Thay đổi thuộc tính của project

Thực thi chương trình thứ hai

using System; using System.Collections.Generic; using System.Linq; using System.Text;

namespace FirstProgram { class Program {

static int Main(string[] args) {

Console.WriteLine("Hello {0} from C#", args[0]); Console.ReadLine(); return 0;

}

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Ghi chú

Điều khiển chương trình C#

(cid:1) Statements

(cid:1) Exceptions

(cid:1) Conditional statements

(cid:1) Loop statements

(cid:1) Jump statements

(cid:1) Console Input/Output

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try – catch statement

Statements

(cid:1) The try - catch statement consists of a try block followed by one

(cid:1) The actions of a program are expressed using statements.

or more catch clauses, which specify handlers for different exceptions.

(cid:1) Several different kinds of statements:

(cid:2) Instruction

Console.WriteLine("Goodbye");

(cid:1) Syntax

try

try_block

(cid:2) Block

catch (exception_declaration_1)

catch_block_1

{ x = 69; y = 96; }

catch (exception_declaration_2)

catch_block_2

(cid:2) Declaration statements

int b = 2, c = 3;

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Exceptions

Xử lý Exceptions

(cid:1) An exception is any error condition or unexpected behavior

(cid:1) A program will crash rarely

(cid:2) encountered by an executing program.

(cid:2) if it has been programmed to recover from situations that may result in an error.

(cid:1) Exceptions can be raised because of

(cid:1) Exceptions are used to anticipate and trap errors that may result in

crashing a program.

(cid:2) a fault in code or in called code (such as a shared library), (cid:2) unavailable operating system resources, (cid:2) unexpected conditions the common language runtime encounters (such as code

(cid:1) The .NET framework provides us with a large range of exception

that cannot be verified),

classes that store information regarding exceptions

(cid:2) and so on.

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try – catch statement: Ví dụ

Xử lý exceptions: Ví dụ

(cid:1) Example

private void button2_Click(object sender, EventArgs e) {

object o2 = null; try {

int i2 = (int)o2; // Error

int c = 0; try {

} catch (InvalidCastException e) { // handle exeption here

}

int a = Convert.ToInt32(textBox1.Text); int b = Convert.ToInt32(textBox2.Text); c = a / b; return;

} catch (DivideByZeroException ex) {

MessageBox.Show(ex.Message);

(cid:1) Handle other exceptions

} catch (FormatException ex) {

MessageBox.Show(ex.Message);

(cid:2) catch without exception declaration (cid:2) finally clause

} catch {

throw;

} finally {

(cid:1) Leave the exception for callers

// always be executed even if 'try' block returns textBox3.Text = c.ToString();

(cid:2) throw statement

}

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checked statement

Xử lý exceptions: Ví dụ

(cid:1) C# statements can execute in either checked or unchecked context.

(cid:2) checked context: arithmetic overflow raises an exception. (cid:2) unchecked context: arithmetic overflow is ignored and the result is truncated.

(cid:1) To specify the context, use checked and unchecked statements.

(cid:1) Operations are affected by the overflow checking

Error Message

(cid:2) ++ -- + - * / (cid:2) Explicit numeric conversions between integral types.

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checked: Ví dụ

Controlling statements

(cid:1) Conditional statements

(cid:1) Checked expression

(cid:2) can decide something using keywords such as if, switch.

short x = 32767; // Max short value short y = 32767; try {

z = checked((short)(x + y));

(cid:1) Loop statements

} catch (System.OverflowException e) {

System.Console.WriteLine(e.ToString());

(cid:2) can create a loop using keywords such as do, while, for, foreach, and in.

}

(cid:1) Jump statements

(cid:1) Checked block

unchecked {

(cid:2) can be used to transfer program control using keywords such as break,

int z = x + y; return z; // Returns -2

continue, return, and yield.

}

(cid:1) Console Input/Output

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if statements

switch statements

(cid:1) if statement

(cid:1) switch statement

switch ( variable ) {

if (boolean_expression)

case val1: statement-or-block;

statement_or_statement_block;

goto case val2;

else if (boolean_expression)

case val2: statement-or-block;

statement_or_statement_block;

goto default;

else

default: statement-or-block;

statement_or_statement_block;

break;

}

(cid:1) Each case must finish with a jump statement (that can be break or

(cid:1) Example

if (myNum == 4)

Console.WriteLine("My number is 4");

goto or return). (cid:2) Empty (stacking) case is allowed (without jump statement).

else

Console.WriteLine("My number is not 4");

(cid:1) The default case is optional.

(cid:2) If no default case is defined, then the default behavior is to do nothing.

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do – while statements

while statements

(cid:1) do … while statement

(cid:1) while statement

do

while ( condition )

statement-or-block;

while ( condition );

(cid:1) Example

int number = 0; do {

TimeSpan durationToRun = new TimeSpan(0, 0, 30); DateTime start = DateTime.Now;

Console.WriteLine(number++.ToString());

} while (number <= 10);

while (DateTime.Now - start < durationToRun) { Console.WriteLine("not finished yet");

}

Console.WriteLine("finished");

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for statements

foreach statements

(cid:1) for statement

(cid:1) foreach statement

for ( initialization; condition; iteration )

foreach ( var_declaration in enumerable_exp )

statement-or-block;

(cid:1) Example

string[] itemsToWrite = {"Alpha", "Bravo",

for (int i = 1, j = 100 * i; // initialization

"Charlie", "Denny"};

foreach (string item in itemsToWrite)

i < 100 && j > 0; // condition i++, j--) { // iteration System.Console.WriteLine((i+j).ToString());

System.Console.WriteLine(item);

}

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Jump statements

Xuất nhập từ bàn phím

(cid:1) break

(cid:1) Read a text line from console

string System.Console.ReadLine();

(cid:2) exit from a case in a switch or exit from a loop.

(cid:1) continue

(cid:2) transfers program control just before the end of a loop.

(cid:1) Write a text line to console

(cid:1) return

void System.Console.Write(); void System.Console.WriteLine();

(cid:2) identifies the return value for the function or method (if any), and transfers

control to the end of the function.

(cid:1) Example

(cid:1) yield

string s1 = Console.ReadLine(); string s2 = Console.ReadLine();

(cid:2) is used to define an iterator block that produces values for an enumerator.

int i = int.Parse(s1); int j = int.Parse(s2);

(cid:1) throw

Console.WriteLine("{0} plus {1} equals {2}", i, j, i + j);

(cid:2) throws an exception.

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Ghi chú

Biến

(cid:1) Variable declaration

int i; int x = 10; y = 20; bool b = true; long x = 0x12ab; // hexa uint ui = 1234U; long l = 1234L;

(cid:1) Constant declaration

const int a = 20; const float pi = 3.14F; const ulong ul = 1234UL; const decimal d = 12.30M;

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Tầm vực của biến

Một số trường hợp đặc biệt

(cid:1) Local scope

(cid:1) Special case of local scope

(cid:2) Within current function or block

for (int i = 0; i < 10; i++) {

Console.WriteLine(i);

} // variable "i" is out of scope

(cid:1) Class scope

(cid:2) Within current object

(cid:1) Another case (which is ok in C++)

(cid:1) Special scope

int j = 20; for (int i = 0; i < 10; i++) {

(cid:2) Captured variables

int j = 30; // error – "j" is already defined Console.WriteLine(j + i);

}

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Khởi động biến cục bộ

Kiểu dữ liệu

(cid:1) Local variables in C# must be initialized before being used.

(cid:1) Value types

(cid:1) Variables are automatically initialized to their default values:

(cid:1) Reference types

(cid:2) Static variables. (cid:2) Instance variables. (cid:2) Array elements.

Type bool

Default false

Type byte

Default 0

char

'\0'

decimal

0.0M

double

0.0D

float

0.0F

int

long

short

uint

ulong

ushort

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Kiểu giá trị – Value Types

Kiểu tham chiếu – Reference Types

(cid:1) Contain directly their value and are customarily created statically.

(cid:1) The lifetime of the resulting object is controlled be garbage collection

services provided by CLR.

(cid:1) Initialization: using the new statement

(cid:1) The reference holds the location of an object created on the

managed heap

(cid:1) Derive from System.ValueType

(cid:1) Primitive types: int, float, char, bool, etc.

(cid:1) Derive from System.Object and created with the new keyword

(cid:1) Non-class types: struct, enum

(cid:1) Types: interfaces, arrays and delegates

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So sánh: Value và Reference

Kiểu giá trị – Value types

(cid:1) Value Types

(cid:1) Primitives types

(cid:2) Just hold a value in memory (cid:2) Are stored in a stack

(cid:1) Structures

(cid:1) Reference Types

(cid:1) Enumerations

(cid:2) Contains the address of the object in the heap (cid:2) is null means that no object has been referenced

Value

Reference

Variable Holds

Actual Value

Reference

Allocated

Inline (Stack) 0

Heap null

Default Value

Parameter to functions

Copy Value

Copy Reference

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Các kiểu dữ liệu cơ sở

Các toán tử

Name

CTS Type

Description

Range

Operator + - * / % & | ^ ~ && || ! + ++ -- << >> == != < > <= >= = += -= *= /= %= &=

Assignment

bool

System.Boolean

|= ^= <<= >>=

true or false

char

System.Char

single 16-bit (Unicode) character

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Các toán tử

Structures

(cid:1) Struct is a value type, not reference type

Operator

(cid:2) so it can be allocated without new.

Member access

[]

Indexing

(cid:1) Struct can have methods like a class.

()

Cast

(cid:1) Struct have default no-parameter constructor

Conditional (Ternary)

(cid:2) which cannot be overridden.

new

Object Creation

sizeof (unsafe code only)

Type information

(cid:1) Struct cannot be inherited.

checked unchecked

Overflow exception control

* -> & (unsafe code only) []

Indirection and Address

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Structures: Ví dụ

Enumerators

(cid:1) Example

(cid:1) Enumerators in C# have numbers associated with the values.

struct StrStudent {

(cid:1) By default, the first element of the enum is assigned a value of 0

public int Id; public string Name; public double GPA;

(cid:2) and is incremented for each subsequent enum element.

public StrStudent(int id, string fn, double gpa) {

(cid:1) The default value can be overridden during initialization.

Id = id; Name = fn; GPA = gpa;

}

(cid:1) Every enumeration type has an underlying type (any integral type

except char), (cid:2) default is int.

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Enumerators : Ví dụ

Ghi chú

(cid:1) Example

public class Holiday {

public enum WeekDays {

Monday, Tuesday, Wednesday, Thursday, Friday

}

public void ProcessWeekday(WeekDays day) {

//Process WeekDays

}

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Kiểu tham chiếu – Reference types

Mảng

(cid:1) An array is a data structure

(cid:1) Arrays

(cid:2) that contains a number of variables of the same type.

(cid:1) Interfaces

(cid:1) Arrays are zero indexed.

(cid:1) Classes

(cid:1) Types of array

(cid:1) Delegates

(cid:2) 1-dimension array (cid:2) Multi-dimension array (cid:2) Jagged array

(cid:1) Others

(cid:1) Array types are reference types

(cid:2) derived from the abstract base type Array.

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Mảng một chiều

Mảng một chiều: Các thao tác

(cid:1) Syntax:

(cid:1) Obtain the length of an array:

type[] array_name;

int arrayLength = myIntegers.Length;

(cid:1) Sort an array of integer:

(cid:1) Examples:

Array.Sort(myIntegers);

int[] myIntegers; // an array of integer

myIntegers = new int[32]; myIntegers[0] = 35;// first element is 35 myIntegers[31] = 432;// 32-th element is 432

(cid:1) Reverse an array:

Array.Reverse(myArray);

string[] myArray = {"first element",

"second element", "third element"};

(cid:1) Traversal:

for (int i=0; i
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Mảng đa chiều

Mảng jagged

(cid:1) Syntax:

(cid:1) A jagged array is an array of arrays

type[,] array_name; type[, , , ,] array_name;

type[][] array_name; type[][][[]] array_name;

(cid:1) Examples:

(cid:1) The elements of a jagged array can be of different dimensions and

sizes.

int[,] myRectArray = new int[2,3]; //3-row-2col array

int[,] myRectArray = new int[,] { {1,2}, {3,4}, {5,6}};

string[,] beatleName = { {"Lennon", "John"},

int[][] a = new int[3][]; a[0] = new int[4]; a[1] = new int[3]; a[2] = new int[1];

{"McCartney", "Paul"}, {"Harrison", "George"}, {"Starkey", "Richard"}

for (int i = 0; i < a.Length; i++) {

};

for (int j = 0; j < a[i].Length; j++) { }

}

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Chuyển kiểu

Chuyển kiểu ngầm định

(cid:1) Many times, it’s necessary to convert instances of one type to

(cid:1) One type of data is automatically converted into another type of data.

another (cid:2) Implicit Conversion

(cid:1) No data loss

(cid:2) Explicit Conversion

(cid:1) Implicit Numerical Conversion

long x; int y = 25; x = y; // implicit numerical conversion

(cid:1) Implicit Enumeration Conversion

(cid:2) Permit the decimal, integer, literal to be converted to any enumerate type

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Chuyển kiểu ngầm định: tham chiếu

Chuyển kiểu tường minh

(cid:1) From any reference type to object.

(cid:1) Using the casting operator ()

(cid:1) From any class type D to any class type B,

(cid:1) May be loss data

(cid:2) provided D is inherited from B.

(cid:1) Explicit Numerical Conversions

(cid:1) From any class type A to interface type I,

(cid:2) provided A implements I.

int x = (int)26.45; // Explicit conversion Console.WriteLine(x); // Displays only 26

(cid:1) From any interface type I2 to any other interface type I1,

(cid:1) Explicit Enumeration Conversions

(cid:2) provided I2 inherits I1.

(cid:2) From any enum type to sbyte, byte, short, ushort, int, uint, long,

ulong, char, float, double or decimal, and vice versa.

(cid:2) From any enum type to any other enum type

(cid:1) From any array type to System.Array. (cid:1) From null to any reference type.

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Chuyển kiểu tường minh: tham chiếu

Boxing và Unboxing

(cid:1) From object to any reference type.

(cid:1) Boxing is conversion of a value type into a reference type.

(cid:1) From any class type B to any class type D,

(cid:2) provided B is the base class of D

(cid:1) Unboxing is the conversion of a reference type into a value type.

(cid:1) From any class type A to any interface type I, (cid:2) provided A is not sealed and do not implement I.

(cid:1) From any interface type I to any class type A,

(cid:2) provided A is not sealed and implement I.

int x = 10; object o1 = x; // Implicit boxing object o2 = (object)x; // Explicit boxing int y = (int)o1;

// Unboxing

(cid:1) From any interface type I2 to any interface type I1,

(cid:2) provided I2 is not derived from I1.

(cid:1) From System.Array to any array type.

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Kiểm tra trước khi chuyển kiểu

“Thử” chuyển kiểu

(cid:1) The is operator

(cid:1) The as operator

(cid:2) Checks if an object is compatible with a given type.

(cid:2) is used to perform conversions between compatible reference types.

(cid:2) evaluates to true if the provided expression is non-null, and the provided object

(cid:2) The as operator is like a cast operation. However, if the conversion is not

possible, as returns null instead of raising an exception.

can be cast to the provided type without causing an exception to be thrown.

(cid:2) only considers reference conversions, boxing conversions, and unboxing

conversions

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Tóm lược

Tham khảo thêm

(cid:1) How to create a program?

(cid:1) Tutorial: Hello World

http://msdn.microsoft.com/en-us/library/aa288463(v=vs.71).aspx

(cid:1) How to manipulate arguments?

(cid:1) How to control a program?

(cid:1) Tutorial: Command Line Parameters

http://msdn.microsoft.com/en-us/library/aa288457(v=vs.71).aspx

(cid:1) How to handle exceptions?

(cid:1) How to use console input/output?

(cid:1) Tutorial: Arrays

http://msdn.microsoft.com/en-us/library/aa288453(v=vs.71).aspx

(cid:1) How to use variables and constants?

(cid:1) Tutorial: Structures

(cid:1) How to use structures, enumerations, and arrays?

http://msdn.microsoft.com/en-us/library/aa288471(v=vs.71).aspx

(cid:1) How to convert between data types?

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Tham khảo thêm

Tham khảo thêm

(cid:1) Tutorial: Getting Started

(cid:1) Types

http://www.csharp-station.com/tutorials/lesson01.aspx

http://msdn.microsoft.com/en-us/library/ms173104.aspx

(cid:1) Tutorial: Operators, Types, and Variables

(cid:1) Value Types

http://www.csharp-station.com/Tutorial/CSharp/Lesson02

http://msdn.microsoft.com/en-us/library/s1ax56ch(v=vs.71).aspx

(cid:1) Tutorial: Control Statements – Selection

(cid:1) Types Reference Tables

http://www.csharp-station.com/Tutorial/CSharp/Lesson03

http://msdn.microsoft.com/en-us/library/1dhd7f2x(v=vs.71).aspx

(cid:1) Tutorial: Control Statements – Loops

(cid:1) Arrays

http://www.csharp-station.com/Tutorial/CSharp/Lesson04

http://msdn.microsoft.com/en-us/library/aa287879(v=vs.71).aspx

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Tham khảo thêm

Ghi chú

(cid:1) Controlling program

http://en.wikibooks.org/wiki/C_Sharp_Programming/Control

(cid:1) Statements

http://msdn.microsoft.com/en-us/library/xt4z8b0f(v=vs.71).aspx

(cid:1) Casting and Type Conversions

http://msdn.microsoft.com/en-us/library/ms173105.aspx

(cid:1) Exceptions and Exception Handling

http://msdn.microsoft.com/en-us/library/ms173160.aspx

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

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Lớp và Interface

Lớp trong C#

(cid:1) Classes are declared by using the keyword class

(cid:2) followed by the class name (cid:2) and a set of class members surrounded by curly braces.

// Namespace Declaration using System;

// Program start class class Welcome {

(cid:1) Classes & Objects (cid:1) Constructors & Destructors (cid:1) Constants & Fields (cid:1) Methods, Properties & Indexers (cid:1) Operators (cid:1) Delegates & Events (cid:1) Anonymous Methods (cid:1) Nested Classes

// Main begins program execution. static void Main() {

// Write to console Console.WriteLine("Welcome to C#");

}

}

(cid:1) Inheritance (cid:1) Polymorphism (cid:1) Abstract classes & Interfaces (cid:1) Namespaces

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Thành phần của lớp

Đối tượng

(cid:1) Members which can be declared in a class:

(cid:1) Objects are instances or specific occurrences of a class.

(cid:2) Constructors, Destructors, Constants, Fields, Methods, Properties, Indexers,

Delegates, Events, Nested Classes.

(cid:1) Objects are created by new operator and referenced by variables of

reference types.

(cid:1) Members are accessed by “dot” operator.

(cid:1) Types of member

(cid:2) Instance class members:

Welcome w = new Welcome(); Customer c = new Customer(); Date d = new Date(); Button btn = new Button();

○ belong to a specific occurrence of a class. ○ be accessed through instances.

(cid:2) Static class members: ○ belong to that class. ○ be accessed through that class.

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Lớp Static

Xác định mức độ truy xuất

(cid:1) A class can be declared static, indicating that it contains only

(cid:1) An access modifier determines how other parts of a program can

static members.

access a class member.

(cid:1) It is not possible to create instances of a static class using the new

(cid:1) Member access is controlled by four access modifiers:

keyword.

(cid:1) Static classes are sealed (cannot be inherited).

(cid:2) public, (cid:2) private, (cid:2) protected, (cid:2) internal.

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Access Modifiers

Access Modifiers

(cid:1) A public member can be accessed by any other code in program.

(cid:1) The internal modifier declares that a member is known throughout

all files in an assembly, (cid:2) but unknown outside that assembly.

(cid:1) A private member can be accessed only by other members of its

class.

(cid:1) The protected internal member (only class members) is

(cid:1) A protected member is public within a class hierarchy,

(cid:2) but private outside that hierarchy.

accessible (cid:2) within its own assembly or (cid:2) to derived types.

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Constructors và Destructors

Hàm khởi động

(cid:1) Every class has at least one constructor,

(cid:1) Constructors are class methods that are executed when an object of

(cid:2) which is called automatically any time an instance of a class is created.

a given type is created.

(cid:1) The purpose of constructors is to initialize class members

(cid:1) Destructors are used to destruct instances of classes.

(cid:2) when an instance of the class is created.

(cid:1) Constructors do not have return values and always have the same

name as the class.

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Khởi động static

Khởi động mặc định

(cid:1) Static constructors are used to initialize static fields in a class.

(cid:1) A constructor that takes no parameters is called a default

constructor.

(cid:1) Declare a static constructor by using the keyword static just in

front of the constructor name.

(cid:1) Unless the class is static, classes without constructors are given a

public default constructor.

(cid:1) A static constructor is called

(cid:1) Default constructors could be overridden for class only.

(cid:2) before an instance of a class is created, (cid:2) before a static member is called, (cid:2) and before the static constructor of a derived class.

(cid:1) Static constructors are called only once.

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Khởi động static: Ví dụ

Khởi động private

(cid:1) Private constructors are used to prevent a class from being

instantiated.

using System; using System.Collections.Generic; using System.Text; using Samsung.Televison; using Sony.Televison;

class Nlog {

public class Bus {

// Static constructor: static Bus() {

Console.WriteLine("The static constructor invoked.");

// Private Constructor: private NLog() { }

} public static void Drive() {

Console.WriteLine("The Drive method invoked.");

public static double e = System.Math.E; //2.71828...

}

}

}

namespace FirstProgram { class Program {

static void Main1() { Bus.Drive(); Bus.Drive(); Console.ReadLine();

}

}

}

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Từ khóa this

Khởi động với tham số

(cid:1) Both classes and structures can define constructors that take

(cid:1) A constructor can invoke another constructor in the same object

(cid:2) using the this keyword.

parameters.

(cid:1) this can be used with or without parameters,

(cid:1) Classes and structures can also define multiple constructors.

(cid:2) and any parameters in the constructor are available as parameters to this.

public class Employee {

public int salary;

public class Employee {

// Constructor with 1 parameter public Employee(int annualSalary) {

public int salary; // Constructor with 1 parameter public Employee(int annualSalary) {

salary = annualSalary;

salary = annualSalary;

}

} // Constructor with 2 parameters public Employee(int weeklySalary, int numberOfWeeks) :

// Constructor with 2 parameters public Employee(int weeklySalary, int numberOfWeeks) {

salary = weeklySalary * numberOfWeeks;

this(weeklySalary * numberOfWeeks) // invoke constructor with 1 parameter

}

{ }

}

}

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Từ khóa base

Hàm dọn dẹp

(cid:1) A constructor can use the base keyword to call the constructor of a

(cid:1) Destructors cannot be defined in structures.

base class.

(cid:2) They are only used with classes.

(cid:1) The base keyword can be used with or without parameters.

(cid:1) A class can only have one destructor.

(cid:1) In a derived class,

(cid:1) Destructors cannot be inherited or overloaded.

(cid:2) if a base-class constructor is not called explicitly using the base keyword, (cid:2) then the default constructor, if there is one, is called implicitly.

(cid:1) Destructors cannot be called. (cid:2) They are invoked automatically.

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Hàm dọn dẹp

Ghi chú

(cid:1) A destructor does not take modifiers or have parameters.

(cid:1) The destructor implicitly calls Finalize on the object's base class.

class Employee {

~Employee() {

Console.WriteLine("Employee's destructor is called");

}

}

class TestDestructor {

static void Main() {

Employee t = new Employee();

}

}

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

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Constants và Fields

Field

(cid:1) Fields are objects or values contained in a class or a structure.

(cid:1) Fields allow classes and structures to encapsulate data.

(cid:1) Constants are values (not objects, except string objects) which are

(cid:1) Fields should generally be private.

(cid:2) Access to fields by external classes should be indirect, by means of methods,

known at compile time and do not change.

properties, or indexers.

(cid:1) Fields are declared within the class block:

;

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Khai báo Field

Hằng số

(cid:1) Classes and structures can declare constants as members.

(cid:1) A field initialization cannot refer to other instance fields.

(cid:1) Constants are declared as a field, using the const keyword before

(cid:1) A field can optionally be declared static.

the type of the field.

(cid:2) This makes the field available to callers at any time, even if no instance of the

class exists.

(cid:1) Constants must be initialized as they are declared.

(cid:1) A field can be declared readonly.

(cid:1) Constants are accessed as if they were static fields,

(cid:2) A read-only field can only be assigned a value during initialization or in a

(cid:2) although they cannot use the static keyword.

constructor.

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Constants và Fields: Ví dụ

Methods, Properties và Indexers

public class CalendarDate {

(cid:1) A method is a code block that contains a series of statements.

(cid:1) A property is a pair of set and get method.

public int month = 7; // declare a field and initialize it public readonly int day = 29; // read-only field public static readonly int year = 2011; // static read-only, MUST be initialized public bool isNewYear = (day == 1 && month == 1); // ERROR: cannot initialize a field from others public bool isNewMelenium = (year % 1000 == 0); // OK: can iniitialize a field from static ones public CalendarDate() {

day = 30; // can be initialized at declaration or in constructor year = 2012; // ERROR: allowed only in static constructor

(cid:1) Indexers enable objects to be indexed in a similar way to arrays.

}

} class Calendar {

public const int months = 12; // declare a constant and MUST initialize it public const int weeks = 52; public const int days = 365; public const double daysPerWeek = days / weeks;// initialize from other constants public const double daysPerMonth = days / months;

} class ConstantsAndFields {

static void Main1() {

CalendarDate birthday = new CalendarDate(); birthday.month = 7; // access fields through instances birthday.month = Calendar.months; // access constants through the class

}

}

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Phương thức

Tham số

(cid:1) Methods are extremely useful

(cid:1) To the method being called, the incoming arguments are called

(cid:2) because they allow to separate your logic into different units.

(cid:1) Information can be passed to methods, one or more statements are

parameters. (cid:2) Arguments: input values (cid:2) Parameters: input variables

performed, and a value is returned.

(cid:1) Method parameters

(cid:1) The capability to pass parameters and return values is optional

(cid:2) and depends on what the method is going to do.

(cid:2) are enclosed in parentheses (cid:2) and are separated by commas.

(cid:1) Empty parentheses indicate that the method requires no parameters.

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Giá trị trả về

Signature của phương thức

(cid:1) Method can return the value using the return keyword.

(cid:1) Method signatures contains

(cid:1) If the method is a void type, the return statement can be omitted.

(cid:1) Methods with a non-void return type are required to use the return

(cid:2) Access level (public, private, etc.) (cid:2) Access modifier (abstract, sealed, etc.) (cid:2) Return value (cid:2) Method name (cid:2) Method parameters

keyword to return a value.

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Từ khóa ref

Truyền tham số

(cid:1) When an object based on a reference type is passed to a method

(cid:1) The ref keyword causes arguments to be passed by reference. (cid:2) Any changes made to the parameter in the method will be reflected in that

variable when control passes back to the calling method.

(cid:2) No copy of the object is made (cid:2) Changes made through the reference will therefore be reflected in the calling

method.

(cid:1) To use a ref parameter,

(cid:2) both the method definition and the calling method must explicitly use the ref

keyword.

(cid:1) When a value type is passed to a method (cid:2) A copy is passed instead of the object itself (cid:2) Any changes made to the parameter have no effect within the calling method.

(cid:1) An argument passed to a ref parameter must first be initialized.

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Từ khóa out

ref và out: Ví dụ

(cid:1) Similar to the ref keyword, the out keyword causes arguments to

struct StructSample { public int i;

}

be passed by reference.

class RefExample {

static void RefMethod(ref StructSample s) {

s.i = 44;

(cid:1) The out does not requires that the variable be initialized before

}

static void OutMethod(out StructSample s) {

being passed.

s = new StructSample(); s.i = 11;

}

(cid:1) To use an out parameter,

static void Main() {

(cid:2) both the method definition and the calling method must explicitly use the out

keyword.

StructSample val_ref = new StructSample(); // default constructor: val_ref.i = 0; RefMethod(ref val_ref); // "ref" is required here // val_ref.i is now 44

StructSample val_out; // no initialization OutMethod(out val_out); // "out" is required here // val_out now point to new StructSample

}

}

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Từ khóa params

params: Ví dụ

public class MyClass {

static void UseIntParams(string str, params int[] list) {

(cid:1) The params keyword

Console.WriteLine(str); for (int i = 0 ; i < list.Length; i++) {

Console.WriteLine(list[i]);

(cid:2) allows to specify a method parameter that takes an argument where the number

of arguments is variable.

} Console.WriteLine();

}

static void UseObjectParams(params object[] list) {

for (int i = 0 ; i < list.Length; i++) {

(cid:1) No additional parameters are permitted after the params keyword in

Console.WriteLine(list[i]);

a method declaration

} Console.WriteLine();

}

static void Main() {

(cid:1) Only one params keyword is permitted in a method declaration.

UseIntParams("Start", 1, 2, 3, 4, 5, 6, 7, 8, 9); UseObjectParams(1, 'a', "Alphabe", true, new MyClass()); // An array of objects can also be // passed, as long as the array type // matches the method being called.

int[] myarray = new int[3] { 10, 11, 12 }; UseIntParams("Second", myarray);

}

}

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Overload một phương thức

Thuộc tính – Properties

public class MyClass {

static void UseIntParams(string str, params int[] list) {

(cid:1) Properties enable a class to expose a public way of getting and

Console.WriteLine(str); for (int i = 0 ; i < list.Length; i++) {

Console.WriteLine(list[i]);

} Console.WriteLine();

setting values, (cid:2) while hiding implementation or verification code.

}

static void UseObjectParams(params object[] list) {

for (int i = 0 ; i < list.Length; i++) {

(cid:1) A get accessor is used to return the property value,

Console.WriteLine(list[i]);

} Console.WriteLine();

and a set accessor is used to assign a new value.

}

static void Main() {

(cid:1) The value keyword is used to define the value being assigned by

the set accessor.

UseIntParams("Start", 1, 2, 3, 4, 5, 6, 7, 8, 9); UseObjectParams(1, 'a', "Alphabe", true, new MyClass()); // An array of objects can also be // passed, as long as the array type // matches the method being called.

(cid:1) Properties that do not implement a set accessor are read only.

int[] myarray = new int[3] { 10, 11, 12 }; UseIntParams("Second", myarray);

}

}

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Thuộc tính

Chỉ mục – Indexers

(cid:1) Syntax to define a property

(cid:1) Indexers enable objects to be indexed in a similar way to arrays.

{

(cid:1) Indexers can be indexed by an integer value or other values.

get { /* ... / } set { / ... / }

}

class TimePeriod {

(cid:1) Indexers can have more than one formal parameter, (cid:2) for example, when accessing a two-dimensional array.

private double seconds; public double Hours {

get { return seconds / 3600; } set { seconds = value 3600; } // "value" indicates the input

}

} class Program {

static void Main() {

TimePeriod t = new TimePeriod(); t.Hours = 24; // "set" accessor is called System.Console.WriteLine("Time in hours: " + t.Hours); // "get" accessor is called

}

}

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Truy xuất các thành phần get và set

Chỉ mục

(cid:1) Syntax to define an indexer

(cid:1) By default accessors have the same visibility, or access level

this[] {

(cid:2) that of the property or indexer to which they belong.

get { /* ... / } set { / ... / }

(cid:1) Accessor modifiers can be used only if the property or indexer has

}

class Sample {

private int[] arr = new int[100];

both set and get accessors. (cid:2) In this case, the modifier is permitted on one only of the two accessors.

public int this[String s, int i] {

get { if (s == "Top") return arr[i]; else return 0; } set { if (s == "Top") arr[i] = value; } // "value" indicates the input

}

} class SampleProgram {

static void Main(string[] args) {

Sample intCol = new Sample(); intCol["Right", 0] = 7; // "set" accessor is called System.Console.WriteLine("{0}", intCol["Top", 0]); // "get" accessor is called

}

}

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Ghi chú

Toán tử

(cid:1) C# allows user-defined types to overload operators

(cid:2) by defining static member functions using the operator keyword.

(cid:1) Unary operators have one parameter,

and binary operators have two parameters.

(cid:1) One parameter must be the same type as the class or structure that

declares the operator.

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

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Overload các toán tử

Toán tử: Ví dụ

(cid:1) The comparison operators, if overloaded, must be overloaded in

public struct Complex { public int real; public int imaginary;

// Constructor. public Complex(int real, int imaginary) {

pairs (cid:2) if == is overloaded, != must also be overloaded (cid:2) similar for < and >, and for <= and >=.

this.real = real; this.imaginary = imaginary;

}

Operators

Overload

+ - ! ~ ++ --

YES

// Specify which operator to overload (+), // the types that can be added (two Complex objects), // and the return type (Complex). public static Complex operator +(Complex c1, Complex c2) {

+ - / % & | ^ << >>

YES

return new Complex(c1.real + c2.real, c1.imaginary + c2.imaginary);

}

== != < > <= >=

YES

&& || [] (T)x

NO

// Override the ToString() method to display a complex number // in the traditional format: public override string ToString() {

+= -= = /= %= &= |= ^= <<= >>=

NO

return (System.String.Format("{0} + {1}i", real, imaginary));

}

}

NO

= . ?: ?? -> => f(x), as, checked, unchecked, default, delegate, is, new, sizeof, typeof

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Delegates và Events

Delegates

(cid:1) A delegate is a type that references a method.

(cid:1) Delegates are similar to C++ function pointers, but are type safe.

(cid:1) Once a delegate is assigned a method,

(cid:1) Events provide a way for a class or object to notify other classes or

(cid:2) it behaves exactly like that method.

objects when something of interest happens.

(cid:1) The delegate method can be used like any other method,

(cid:2) with parameters and a return value.

(cid:1) Any method

(cid:2) that matches the delegate's signature (do not need match exactly), which

consists of the return type and parameters,

(cid:2) can be assigned to the delegate.

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Delegates

Covariance và Contravariance

(cid:1) Delegates are similar to C++ function pointers, but are type safe.

(cid:1) Covariance and contravariance provide a degree of flexibility

(cid:2) when matching method signatures with delegate types.

(cid:1) Delegates allow methods to be passed as parameters.

(cid:1) Covariance permits a method

(cid:1) Delegates can be used to define callback methods.

(cid:2) to have a more derived return type than what is defined in the delegate.

(cid:1) Delegates can be chained together;

(cid:1) Contravariance permits a method

(cid:2) for example, multiple methods can be called on a single event.

(cid:2) with parameter types that are less derived than in the delegate type.

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Covariance: Ví dụ

Contravariance: Ví dụ

class Mammals { }

class Mammals { }

class Dogs : Mammals { }

class Dogs : Mammals { }

class MyProgram {

class Program {

// Define the delegate: accept a "Dog" and return nothing public delegate void HandlerMethod(Dogs d);

// Define the delegate: no parameter and return a "Mammal" public delegate Mammals HandlerMethod();

// method 1 return a "Mammal" public static Mammals FirstHandler() {

// method 1 receive a "Mammal" // if a "Dog" is passed, it works fine since a "Dog" is also a "Mammal" public static void FirstHandler(Mammals m) {

return null;

return;

}

}

// method 2 return a "Dog" which is also a "Mammal" public static Dogs SecondHandler() {

// method 2 receive a "Dog" public static void SecondHandler(Dogs d) {

return null;

return;

}

}

static void Main() {

static void Main1() {

// signature of method 1 is exactly matched with delegate HandlerMethod handler1 = FirstHandler;

// Contravariance allows this delegate. HandlerMethod handler1 = FirstHandler;

// Covariance allows this delegate. HandlerMethod handler2 = SecondHandler;

// signature of method 2 is exactly matched with delegate HandlerMethod handler2 = SecondHandler;

}

}

}

}

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Sự kiện – Events

Events

(cid:1) Events provide a way for a class or object

(cid:1) An event can have multiple subscribers.

(cid:2) A subscriber can handle multiple events from multiple publishers.

(cid:2) to notify other classes or objects (cid:2) when something of interest happens.

(cid:1) Events that have no subscribers are never called.

(cid:1) The class that sends (or raises) the event is called the publisher and the classes that receive (or handle) the event are called subscribers.

(cid:1) Events are commonly used to signal user actions

(cid:2) such as button clicks or menu selections in graphical user interfaces.

(cid:1) The publisher determines when an event is raised; the subscribers determine what action is taken.

(cid:1) When an event has multiple subscribers, (cid:2) the event handlers are invoked synchronously.

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Events: Ví dụ

Phương thức Anonymous

(cid:1) In versions of C# before 2.0,

// Declare the delegate public delegate void SampleEventHandler(object sender, SampleEventArgs e); public class Publisher {

(cid:2) the only way to declare a delegate was to use named methods.

// Declare the event. public event SampleEventHandler SampleEvent; // Wrap the event in a protected virtual method protected virtual void RaiseSampleEvent() {

(cid:1) C# 2.0 introduced anonymous methods.

// Raise the event SampleEvent(this, new SampleEventArgs("Hello"));

}

} public class Subscriber {

(cid:1) In C# 3.0 and later, lambda expressions supersede anonymous

void HandleSampleEvent(object sender, SampleEventArgs a) {

// Do something useful here.

methods as the preferred way to write inline code.

} public void subcribe() {

Publisher publisher = new Publisher(); // subscribe to the event publisher.SampleEvent += new SampleEventHandler(HandleSampleEvent); // C# 1.0 publisher.SampleEvent += HandleSampleEvent; // C# 2.0

// unsubscribe from the event publisher.SampleEvent -= HandleSampleEvent;

}

}

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Sử dụng phương thức Anonymous

Phạm vi Anonymous

(cid:1) By using anonymous methods,

(cid:1) The scope of the parameters of an anonymous method

(cid:2) is the anonymous-method-block.

(cid:2) the coding overhead in instantiating delegates is reduced (cid:2) because it does not need to create a separate method.

(cid:1) It is an error

(cid:2) to have a jump statement, such as goto, break, or continue, inside the

(cid:1) Creating anonymous methods is essentially a way

anonymous method block if the target is outside the block.

(cid:2) to pass a code block as a delegate parameter.

(cid:1) It is also an error

// Create a delegate. delegate void Del(int x); // Instantiate the delegate using an anonymous method. Del d = delegate(int k) { / ... / };

(cid:2) to have a jump statement, such as goto, break, or continue, outside the

anonymous method block if the target is inside the block.

// Create a handler for a click event. button1.Click += delegate(System.Object o, System.EventArgs e) {

System.Windows.Forms.MessageBox.Show("Click!");

}; System.Threading.Thread t1 = new System.Threading.Thread(delegate() {

System.Console.Write("Hello, "); System.Console.WriteLine("World!");

});

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Biến Outer

Đặc điểm của biến Outer

(cid:1) The local variables and parameters

(cid:1) The lifetime of a captured variable

(cid:2) whose scope contains an anonymous method declaration are

(cid:2) extends until the delegates that reference the anonymous methods are eligible

called outer variables of the anonymous method.

for garbage collection.

(cid:1) An anonymous method cannot access the ref or out parameters of

(cid:1) A reference to the outer variable

an outer scope.

(cid:2) is said to be captured when the delegate is created.

void TestAnonymous(ref int N) {

(cid:1) Anonymous methods are not allowed on the left side of the is

int n = 0; Del d = delegate(int nn) {

System.Console.WriteLine("Copy #:{0}", ++n);

operator.

// Cannot use ref or out parameter 'N' inside an // anonymous method, lambda expression, or query expression System.Console.WriteLine("Copy #:{0}", ++N);

};

}

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Lambda

Biểu thức Lambdas

(cid:1) A lambda expression is an anonymous function

(cid:1) A lambda expression with an expression on the right side

(cid:2) that can used to create delegates or expression tree types.

(cid:2) is called an expression lambda.

(input parameters) => expression

(cid:1) By using lambda expressions, local functions can be

(cid:1) The parentheses are optional only if the lambda has one input

(cid:2) passed as arguments or (cid:2) returned as the value of function calls.

parameter; otherwise they are required.

delegate int del(int i); static void TestLambda() {

del myDelegate = x => x x; int j = myDelegate(5); // j = 25

(x, y) => x == y

}

(int x, string s) => s.Length > x

○ The delegate signature has one implicitly-typed input parameter of type int, and

returns an int.

() => SomeMethod()

○ The lambda expression also has one input parameter and a return value

x => x > 0

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Phát biểu Lambda

Kiểu dữ liệu Nested

(cid:1) A statement lambda resembles an expression lambda

(cid:1) A type defined within a class or structure is called a nested type.

(cid:2) except that the statement(s) is enclosed in braces.

(cid:1) Nested types default to private,

(input parameters) => { statements; }

(cid:2) but can be made public, protected internal, protected, internal, or

private.

(cid:1) The body of a statement lambda can consist of any number of

(cid:1) The nested, or inner type can access the containing, or outer type.

statements; (cid:2) however, in practice there are typically no more than two or three.

(cid:2) Nested types can access private and protected members of the containing

type, including any inherited members.

delegate void TestDelegate(string s); // ... TestDelegate myDel = n => {

string s = n + " " + "World"; Console.WriteLine(s);

}; myDel("Hello");

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Kiểu dữ liệu Nested: Ví dụ

Ghi chú

(cid:1) Example

public class Container {

private int priv;

public class Nested {

private int my_priv;

public Nested() { } public Nested(Container parent) {

my_priv = parent.priv;

}

}

}

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

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Kế thừa – Inheritance

Kế thừa trong C#

(cid:1) Declare and use a new class as a descendant of another class

(cid:1) The class from which the other classes can inherit is called base

class.

(cid:1) Saves trouble of re-writing code

(cid:1) Two types of Inheritance:

(cid:1) Provides luxury of code re-use

(cid:2) Single Inheritance (cid:2) Multiple Inheritance

(cid:1) A class can inherit from only one class, but can implement many

interfaces. (cid:2) At that time, in the list of base types, the class must go first.

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Single Inheritance

Multiple inheritance

using System; namespace Sample {

class Shape {

interface IConstructionVehicle {

void ExecuteDump(); void TurnOnBackUpSound();

public int length; public int breadth; public void calculateArea(int len, int breadth) { }

} interface Ivehicle {

}

}

void Accelerate(); void Stop(); void TurnOnBackUpSound();

}

class Rectangle : Shape { public Rectangle() {

public class DumpTruck : IVehicle, IConstructionVehicle {

length=0; breadth=0;

void IConstructionVehicle.TurnOnBackUpSound() {

Console.WriteLine("IConstructionVehicle TurnOnBackUpSound");

} public void calculateRectArea(int len, int breadth) {

Console.WriteLine ("Area of a Rectangle is {0}", len * breadth);

} void IVehicle.TurnOnBackUpSound() {

}

Console.WriteLine("IVehicle TurnOnBackUpSound");

}

}

}

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Đóng seal một lớp

Đa hình Polymorphism

(cid:1) A class is sealed

(cid:1) Polymorphism

(cid:2) when no class should be allowed to inherit from that class.

(cid:2) decision as to which method to call is made at runtime.

(cid:1) Keyword sealed is used to seal a class.

(cid:1) Polymorphism means

(cid:2) the “right” method gets called, (cid:2) the one belonging to the actual object that is being referenced.

(cid:1) Example

(cid:1) Code is easier to understand.

// ... sealed class ClassOne {

// Class Implementation

} // ...

(cid:1) Helps the programmer to remember available functionality.

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Từ khóa virtual

Đa hình trong C#

(cid:1) C# enables polymorphism through inheritance.

(cid:1) Keyword virtual is used in the definition of a method to support

polymorphism.

(cid:1) Through inheritance, a class can be used as more than one type

(cid:1) Used to modify method declaration in a class

(cid:2) it can be used as its own type, (cid:2) any base types, (cid:2) or any interface type if it implements interfaces.

(cid:1) Child classes are free to implement their own versions of virtual

method using override keyword.

(cid:1) Polymorphism keywords

(cid:1) virtual modifier cannot be used

(cid:2) with modifiers like static and override

(cid:2) virtual (cid:2) override (cid:2) sealed (cid:2) new

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Từ khóa override

Đa hình: Ví dụ

class Class1 {

(cid:1) Used to modify a method

public virtual void Hello() {

System.Console.Write("Hello from Class1");

}

}

(cid:1) An override method provides a new implementation of the base

class Class2 : Class1 {

public override void Hello() {

method. (cid:2) The base method should be declared as virtual (or abstract)

base.Hello(); System.Console.Write(" and hello from Class2 too");

}

public static void Main1(string[] args) {

(cid:1) Accessibility level of a base method cannot be changed by a method

overriding it.

Class2 c2 = new Class2(); c2.Hello(); System.Console.WriteLine(); Class1 c1 = new Class2(); c1.Hello(); System.Console.ReadLine();

}

(cid:1) Keywords new, static, virtual cannot be used along with

}

override modifier

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Từ khóa sealed

Từ khóa new

(cid:1) Virtual members remain virtual indefinitely

(cid:1) Used as a modifier.

(cid:2) No matter how many classes have been declared between the class that

originally declared the virtual member.

(cid:1) new modifier is used to explicitly

(cid:2) hide a member that is inherited from the base class.

(cid:1) A derived class can stop virtual inheritance by declaring an override

as sealed.

(cid:1) sealed methods can be replaced by derived classes

(cid:2) using the new keyword.

(cid:1) It is an error

(cid:2) to use both new and override on the same method.

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Đa hình: Ví dụ

Ghi chú

public class Base {

public static int val = 123;

} public class Derv : Base {

public static int val = 456; // WARNING: new modifier required to hide "val" from base class

}

class IntAddition {

public virtual void add() { // "add" is virtual Console.WriteLine("The Sum of the two numbers");

}

} class FloatAddition : IntAddition {

public sealed override void add() { // prevent derived class to override

Console.WriteLine("The Sum of the two float numbers");

}

} class StringAddition : FloatAddition {

public new void add() { // hide "add" from base class

Console.WriteLine("The Sum of the two strings");

}

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

}

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Lớp trừu tượng và Interfaces

Lớp trừu tượng

(cid:1) Abstract base classes

(cid:1) The abstract classes are classes solely for the purpose of inheritance

(cid:2) cannot be instantiated nor can they be sealed.

(cid:2) to define features of derived, non-abstract classes.

(cid:1) The purpose of an abstract class is to provide a common definition of

(cid:1) Abstract class definitions are not complete (cid:2) derived classes must define the missing pieces.

a base class (cid:2) that multiple derived classes can share.

(cid:1) An interface contains definitions for a group of related functionalities

(cid:1) C# allows creation of Abstract Base classes

(cid:2) that a class or a structure can implement.

(cid:2) by an addition of the abstract modifier to the class definition.

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Đặc tính của lớp trừu tượng

Sử dụng lớp trừu tượng

(cid:1) Abstract classes may also define abstract methods.

(cid:1) If a virtual method is declared abstract,

(cid:2) it is still virtual to any class inheriting from the abstract class.

(cid:1) Abstract methods have no implementation

(cid:2) and its actual implementation is written in the derived class.

(cid:1) A class inheriting an abstract method

(cid:2) cannot access the original implementation of the method.

public class D {

(cid:1) Derived classes of the abstract class must implement all abstract

public virtual void DoWork(int i) { // Original implementation.

methods.

}

} public abstract class E : D {

(cid:1) Abstract methods can override virtual methods.

public abstract override void DoWork(int i); // change virtual to abstract

} public class F : E {

public override void DoWork(int i) {

// New implementation. // cannot access DoWork of class D

}

}

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Interfaces

Kế thừa Interface

(cid:1) An interface is a pure abstract base class.

(cid:1) New Interfaces can be created

(cid:2) by combining together other interfaces.

(cid:1) It can contain only abstract methods and no method implementation.

(cid:1) The syntax for this is similar to that used for inheritance,

(cid:2) except that more than one interface can be merged to form a single interface.

(cid:1) A class that implements a particular interface

(cid:2) must implement the members listed by that interface.

interface IAllFile : IFile, IFileTwo {

// More operations can be added if necessary //(apart from that of IFile & IFileTwo)

public interface IFile {

}

// method declaration of interface int delFile(); void disFile();

}

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Các thành phần của Interface

Trừu tượng hóa Interface

// interface public interface ICompare {

(cid:1) Interface members are automatically public, (cid:2) and they can't include any access modifiers.

int GetValue(); int Compare(ICompare ic);

} // abstract abstract public class BaseClass : ICompare {

(cid:1) An interface can specify

int nValue; public BaseClass(int nInitialValue) {

nValue = nInitialValue;

public interface ISampleInterface {

} public int Value {

get { return GetValue(); }

// interface property type name {

get; set;

}

} public int GetValue() { return nValue;

(cid:2) a property (cid:2) an indexer (cid:2) an event (cid:2) a method

} public abstract int Compare(ICompare bc);

// interface indexer element_type this[int index] {

get; set;

}

} // implement interface and abstract class public class SubClass : BaseClass {

public SubClass(int nInitialValue) : base(nInitialValue) { } public override int Compare(ICompare ic) {

// interface event event delegate_type event_name;

return GetValue().CompareTo(ic.GetValue());

}

}

}

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Hiện thực hóa Interface

Hiện thực ngầm định – implicit

(cid:1) A class can implement two interfaces

interface IControl { void Paint();

(cid:2) that contain a member with the same signature.

} interface ISurface { void Paint();

} public class SampleClass : IControl, ISurface {

(cid:1) If the class implement that member,

// Both ISuface.Paint() and IControl.Paint call this method public void Paint() {

(cid:2) both interfaces to use that member as their implementation.

System.Console.WriteLine("Paint method in SamppleClass");

}

}

class Test {

(cid:1) If the two interface members do not perform the same function,

static void Main() {

(cid:2) however, this can lead to an incorrect implementation of one or both of the

SampleClass sc = new SampleClass(); IControl ctrl = (IControl)sc; ISurface srfc = (ISurface)sc;

interfaces.

// The following lines all call the same method. sc.Paint(); // Output: Paint method in SamppleClass ctrl.Paint(); // Output: Paint method in SamppleClass srfc.Paint(); // Output: Paint method in SamppleClass

}

}

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Hiện thực tường minh – explicit

Hiện thực tường minh

interface IControl { void Paint();

(cid:1) An explicitly implemented member cannot be accessed through a

} interface ISurface { void Paint();

class instance, (cid:2) but only through an instance of the interface.

} public class SampleClass : IControl, ISurface {

void IControl.Paint() {

System.Console.WriteLine("IControl.Paint");

(cid:1) If an interface member is not implemented explicitly,

} void ISurface.Paint() {

System.Console.WriteLine("ISurface.Paint");

(cid:2) the instance implementation is used.

}

}

class Test {

static void Main() {

SampleClass sc = new SampleClass(); IControl ctrl = (IControl)sc; ISurface srfc = (ISurface)sc;

sc.Paint(); // ERROR: Compiler error. ctrl.Paint(); // Calls IControl.Paint on SampleClass. srfc.Paint(); // Calls ISurface.Paint on SampleClass.

}

}

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Namespaces

Khai báo namespace

(cid:1) Used to avoid naming conflicts.

class SonyTVLCD { } class SonyTVCRT { } class SonyTVFlatron { } class SonyTVPlasma : SonyTVFlatron { }

(cid:1) Elements designed to help us organize our code.

class SamsungLCD { } class SamsungTVCRT { } class SamsungTVFlatron : SamsungLCD { } class SamsungTVPlasma { }

(cid:1) Reduces complexity when code is to be re-used for some other

application.

namespace Sony.Televison {

public class LCD { } public class CRT { } public class Flatron { } public class Plasma : Flatron { } // "Flatron" is unqualified class name

(cid:1) Namespace System contains all the code required to interact with

} namespace Samsung {

the system.

public class LCD { } namespace Televison { // nested namespace

(cid:1) Nested namespaces are child namespaces of other namespaces.

public class CRT { } public class Flatron : LCD { } // "LCD" is unqualified class name public class Plasma : Flatron { } // "Flatron" is unqualified class name

}

}

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Truy xuất Namespace

“Tên đầy đủ”

(cid:1) Namespaces are implicitly public.

(cid:1) To use a class inside its namespace, we need to specify the class

name only. (cid:2) This is known as unqualified naming.

(cid:1) Namespaces cannot be protected, private or internal.

namespace Sony.Televison {

(cid:1) To use a class outside a namespace it has to be referred by using its

fully qualified name as

public class LCD { } public class CRT { } public class Flatron { } public class Plasma : Flatron { } // "Flatron" is unqualified class name

namespace.nested_namespace.class_name

} namespace Samsung {

public class LCD { } public namespace Televison { // ERROR: namespace cannot have modifiers

(cid:1) Example

public class CRT { } public class Flatron : LCD { } // "LCD" is unqualified class name public class Plasma : Flatron { } // "Flatron" is unqualified class name

}

}

System.Console System.Net.Security.SslStream System.Windows.Forms.Button

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Từ khóa using

Sử dụng “alias”

(cid:1) With qualified naming

(cid:2) the code gets longer and confusing.

(cid:1) using alias directives provides us with the facility (cid:2) to pull just one class from the namespace into the scope.

(cid:1) With “using namespaces” statement,

(cid:1) Syntax

(cid:2) long confusing names can be made short and meaningful.

using cls_alias = qualified_path_to_class; using ns_alias = qualified_path_to_namespace;

(cid:1) The using namespace directives can have global scope (cid:2) provided they are declared before any member declarations.

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using: Ví dụ

Các Namespace thông dụng

using Samsung.Televison; using Sony.Televison;

Namespace/Class

Description

namespace TestQualified { public class TestTV {

public void ChooseTV() {

System

Much of the functionality of the BCL is contained within this namespace. It comprises of various other namespaces within it.

// use qualified class names Samsung.Televison.Flatron tv1 = new Samsung.Televison.Flatron(); Sony.Televison.Plasma tv2 = new Sony.Televison.Plasma();

}

System.Array class

}

Contains methods for manipulating arrays.

}

System.Threading

Contains classes for Multi-Threading.

namespace TestUnqualified {

System.Math class

Contains methods for performing mathematical functions.

// alias Flatron here: TestUnqualified.CRT ~~ Samsung.Televison.CRT using CRT = Samsung.Televison.CRT;

public class TestTV {

System.IO

public void ChooseTV() {

Contains classes for reading and writing to files and streams.

System.Reflection

Contains classes for reading metadata from assemblies.

// use unqualified class names through "using namespace" LCD tv1 = new LCD(); // LCD of "Sony.Televison" namespace CRT tv4 = new CRT(); // CRT of "TestUnqualified" ~ Samsung.Televison.CRT Flatron tv3 = new Flatron(); // Flatron of which namespace ????

}

System.Net

}

Contains classes for Internet access and socket programming

}

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Tóm lược

Tóm lược

(cid:1) How to declare a class with members?

(cid:1) How to make class properties and indexers?

(cid:1) How to protect class members?

(cid:1) What is delegates and events?

(cid:1) How to write class methods?

(cid:1) How to subscribe and unsubscribe to events?

(cid:1) How to overload class methods?

(cid:1) How to use anonymous methods and lambdas?

(cid:1) How to overload operators for a class?

(cid:1) How to use interfaces and abstract classes?

(cid:1) How to use namespaces to organize classes?

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Tham khảo thêm

Tham khảo thêm

(cid:1) Tutorial: Delegates

(cid:1) Tutorial: Properties

http://msdn.microsoft.com/en-us/library/aa288470(v=vs.71).aspx

http://msdn.microsoft.com/en-us/library/aa288467(v=vs.71).aspx

(cid:1) Tutorial: Events

(cid:1) Tutorial: Indexers

http://msdn.microsoft.com/en-us/library/aa288465(v=vs.71).aspx

http://msdn.microsoft.com/en-us/library/aa645739(v=vs.71).aspx

(cid:1) Asynchronous Programming with Async and Await

(cid:1) Tutorial: Indexed Properties

http://msdn.microsoft.com/en-us/library/hh191443.aspx

http://msdn.microsoft.com/en-us/library/aa288464(v=vs.71).aspx

(cid:1) Tutorial: Operator overloading

http://msdn.microsoft.com/en-us/library/aa288467(v=vs.71).aspx

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Tham khảo thêm

Tham khảo thêm

(cid:1) Tutorial: Methods

(cid:1) Members

http://www.csharp-station.com/Tutorial/CSharp/Lesson05

http://msdn.microsoft.com/en-us/library/ms173113.aspx

(cid:1) Tutorial: Properties

(cid:1) Methods

http://www.csharp-station.com/Tutorial/CSharp/Lesson10

http://msdn.microsoft.com/en-us/library/ms173114.aspx

(cid:1) Tutorial: Indexers

(cid:1) Covariance and Contravariance

http://www.csharp-station.com/Tutorial/CSharp/Lesson11

http://msdn.microsoft.com/en-us/library/ee207183.aspx

(cid:1) Tutorial: Overloading Operators

(cid:1) Events

http://www.csharp-station.com/Tutorial/CSharp/Lesson18

http://msdn.microsoft.com/en-us/library/awbftdfh(v=vs.80).aspx

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Tham khảo thêm

Ghi chú

(cid:1) Overloadable operators

http://msdn.microsoft.com/en-us/library/8edha89s.aspx

(cid:1) Anonymous Functions

http://msdn.microsoft.com/en-us/library/bb882516.aspx

(cid:1) Interfaces

http://msdn.microsoft.com/en-us/library/vstudio/ms173156.aspx

(cid:1) Explicit Interface Implementation

http://msdn.microsoft.com/en-us/library/ms173157.aspx

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

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Window Forms

(cid:1) Graphic User Interface

(cid:1) Windows Forms

(cid:1) Event-Handling Model

Chương 3

(cid:1) Common controls

(cid:1) Containers

(cid:1) Menu and Toolbars

(cid:1) Custom Controls

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Giao diện đồ họa

Các thành phần giao diện cơ bản

(cid:1) Label

(cid:1) Graphical User Interface (GUI)

(cid:2) Used to display text or images that cannot be edited by the user.

(cid:2) Allows interaction with program visually (cid:2) Is an set of visual objects (components), accessed via keyboard or mouse.

(cid:1) TextBox

(cid:2) An area in which the user inputs data from the keyboard. The area also can

display information.

(cid:1) Types of GUI applications (cid:2) Windows Forms applications (cid:2) Web applications

(cid:1) Button

(cid:2) allows the user to click it to perform an action.

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Các thành phần giao diện cơ bản

Windows Forms

(cid:1) CheckBox

(cid:1) Window Form applications are GUI applications

(cid:2) A GUI control that is either selected or not selected.

(cid:2) run on Microsoft Windows operating systems.

(cid:1) ComboBox

(cid:1) .NET framework provides classes

(cid:2) A drop-down list of items from which the user can make a selection, by clicking

(cid:2) to build up Window Form applications rapidly.

an item in the list or by typing into the box, if permitted.

(cid:1) Assembly: System.Windows.Forms.dll

(cid:1) Panel

(cid:2) A container in which components can be placed.

(cid:1) Namespace: System.Windows.Forms

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Cửa sổ Form

Các Controls và Events

(cid:1) Customized forms contain standard and custom controls to build up

(cid:1) Control

the user interface.

(cid:2) Component with graphical part, such as button or label (cid:2) Are visible

(cid:1) Event

(cid:2) Generated by movement from mouse or keyboard (cid:2) Event handlers performs action (cid:2) Specifics written by programmer

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Các thành phần Windows Forms

Tạo một cửa sổ Form

(cid:1) To add new form, select “Windows Form” from menu “Add”

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Lớp Form

Thiết kế giao diện cửa sổ Form

(cid:1) Visual Studio creates a designer to help user to design the form.

(cid:1) Visual Studio automatically creates a new class inherited from

System.Windows.Forms.Form class.

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Tùy chỉnh cửa sổ Form

Các thuộc tính của cửa sổ Form

Property

Description

(cid:1) To help user to customize the form (change its properties), Visual

Studio provides “Properties” window.

BackColor/ForeColor Color of background and text

BackGroundImage

Background image of the form

AcceptButton

The button which will fire “click” event whenever user press “enter”

CancelButton

The button which will fire “click” event whenever user press “escape”

Controls

The collection of child controls. It allows to add/remove controls programmatically

FormBorderStyle

Border style of the form

Opacity

How transparent the form is.

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Các thuộc tính của cửa sổ Form

Các thao tác trên cửa sổ Form

Method

Description

Property

Description

AutoSize

Allow form to automatically calculate its size

Show()

Show the form and allow users to focus to parent forms

CauseValidation

Allow child controls to fire “Validate” event which used to validate data input.

ShowDialog()

TopMost

Allow the form to be put over all other forms

Show the form and users can only focus to parent forms once the form is closed. Return type: DialogResult.

WindowState

Close()

{Normal, Minimized, Maximized}. The starting state of the form.

Close the form

Cursor

Style of the cursor when it enters the form.

this.DialogResult = DialogResult.OK

Set dialog result to “OK” before closing the form

Icon

Icon of the form

This.DialogResult = DialogResult.Cancel

Set dialog result to “Cancel” before closing the form

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Các sự kiện trên cửa sổ Form

Mô hình xử lý sự kiện

Event

Description

(cid:1) GUIs are event driven.

Load

The event which is fired after the form has been loaded successfully.

(cid:1) Event handlers

(cid:2) Methods that process events and perform tasks.

Paint

The event which is fired whenever the form need to redrawn.

Closed

Occur when the form is closed

(cid:1) Associated delegates

Closing

Occur when the form is closing

(cid:2) Objects that reference methods (cid:2) Contain lists of method references

Keyboard-related events

○ Must have same signature

KeyPress, KeyDown,...

(cid:2) Intermediaries for objects and methods (cid:2) Signature for control’s event handler

Mouse-related events

MouseHover, MouseDown, MouseLeave

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Mô hình xử lý sự kiện

Xử lý sự kiện

(cid:1) Event handler

(cid:2) Must have same signature as corresponding delegate (cid:2) Must be registered with delegate object

○ Add event handlers to the delegate’s invocation list

(cid:2) New delegate object for each event handler

Handler 1 for event E

calls

calls

(cid:1) Event multicasting

Object A raises event E

Delegate for event E

Handler 2 for event E

(cid:2) Have multiple handlers for one event (cid:2) Order called for event handlers is indeterminate

Handler 3 for event E

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Đăng ký xử lý sự kiện

Đăng ký xử lý sự kiện

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Xử lý sự kiện chuột

Thông tin về sự kiện chuột

Event

Description

(cid:1) MouseEventArg: Provides data for the MouseUp, MouseDown, and

MouseMove events.

MouseEnter

Occurs when the mouse cursor enters the area of the control.

(cid:2) Button: Mouse button that was pressed (left, right, middle or none).

MouseLeave

Occurs when the mouse cursor leaves the area of the control.

(cid:2) Clicks: The number of times the mouse button was clicked.

MouseDown

Occurs when the mouse button is pressed while its cursor is over the area of the control.

(cid:2) X: The x - coordinate of the event, relative to the component.

MouseHover

Occurs when the mouse cursor hovers over the area of the control.

(cid:2) Y: The y - coordinate of the event, relative to the component.

MouseMove

Occurs when the mouse cursor is moved while in the area of the control.

MouseUp

Occurs when the mouse button is released when the cursor is over the area of the control.

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Xử lý sự kiện bàn phím

Thông tin về sự kiện bàn phím

(cid:1) KeyEventArgs: Provides data for the KeyDown and KeyUp events.

Event

Description

(cid:2) Shift: Indicates whether the Shift key was pressed.

KeyDown

Occurs when key is initially pushed down.

KeyUp

Occurs when key is released.

(cid:2) Handled: Whether the event was handled.

KeyPress

Occurs when the control has focus and the user presses and releases a key.

(cid:2) KeyCode: Returns the key code for the key, as a Keys enumeration.

(cid:1) KeyEventArg provides data for the KeyDown and KeyUp events.

(cid:2) KeyData: Returns the key code as a Keys enumeration, combined with

modifier information.

(cid:1) KeyPressEventArg provides data for the KeyPress event.

(cid:2) KeyValue: Returns the key code as an int, rather than as a Keys

enumeration.

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Thông tin về sự kiện bàn phím

Ghi chú

(cid:1) KeyPressEventArg provides data for the KeyPress event.

(cid:2) KeyChar: Returns the ASCII character for the key pressed.

(cid:2) Alt: Indicates whether the Alt key was pressed.

(cid:2) Control: Indicates whether the Control key was pressed.

(cid:2) Handled: Whether or not the KeyPress event was handled.

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

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Các thành phần giao diện phổ biến

Các thuộc tính chung

(cid:1) .NET framework provides many common controls

Property

Description

BackColor

Background color of the control.

BackgroundImage

Background image of the control.

Enabled

Whether the control is enabled (i.e., if the user can interact with it). A disabled control will still be displayed, but “grayed-out”—portions of the control will become gray.

Focused

Whether a control has focus.

Font

Font used to display control’s Text.

ForeColor

Foreground color of the control. This is usually the color used to display the control’s Text property.

(cid:2) Label (cid:2) TextBox (cid:2) Button (cid:2) CheckBox (cid:2) CheckedListBox (cid:2) RadioButton (cid:2) ListBox (cid:2) ListView (cid:2) TreeView (cid:2) DateTimePicker (cid:2) …

TabIndex

Tab order of the control..

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Các thuộc tính chung

Các thao tác chung

Property

Method

Description

TabStop

Focus()

Transfers the focus to the control.

Description If true, user can use the Tab key to select the control.

Hide()

Hides the control (sets Visible to false).

Text

Text associated with the control. The location and appearance varies with the type of control.

Show()

Shows the control (sets Visible to true).

TextAlign

The alignment of the text on the control.

BringToFront()

Brings the control to the front of the z-order.

Visible

Whether the control is visible or hidden.

GetChildAtPoint()

Retrieves the child control that is located at the specified coordinates.

Anchor

Side of parent container at which to anchor control—values can be combined, such as Top, Left.

Invoke()

Dock

Side of parent container to dock control—values cannot be combined.

Executes the specified delegate on the thread that owns the control's underlying window handle.

Size

Scale()

Scales the control and any child controls.

Size of the control. Takes a Size structure, which has properties Height and Width.

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Ví dụ

Labels

(cid:1) Manipulating the Anchor property of control.

(cid:1) Used to display text or images that cannot be edited by the user.

(cid:1) Common Properties

(cid:2) Fonts: The font used by the text on the Label (cid:2) Text: The text to appear on the Label. (cid:2) TextAlign: The alignment of the Label’s text on the control.

Control expands along top portion of the form

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Text Boxes

Thuộc tính của Text Box

(cid:1) An area in which the user inputs data from the keyboard.

Property

Description

(cid:2) The area also can display information.

Text

The text of the textbox

TextLength

The length of text in the textbox. (read-only)

(cid:1) Masked Tex tBox: Used to prompt for text input following a mask.

TextAlign

How text is aligned in textbox

Multiline

The value indicating whether this is a multiline textbox

PasswordChar

The char used to mask chars of a password.

SelectedText

The value indicates the current selected text

SelectionStart The starting point of text selected in the textbox

ReadOnly

The value indicating whether text in the text box is read-only

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Thuộc tính Mask

Các sự kiện trên Text Box

(cid:1) Mask

Event

Description

(cid:2) get or set the mask of the masked textbox.

TextChanged

Occurs when the Text property value changes

(cid:1) Use predefined masks

Occurs when the control is validating (lost focus). Parameters:

Validating

object sender, CancelEventArgs e

KeyPress

Occurs when a key is pressed while the control has focus. Parameters:

object sender, KeyPressEventArgs e

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Hiệu chỉnh Mask

Buttons

(cid:1) Button control allows the user to click it to perform an action.

(cid:2) The Button control can display both text and images.

Masking element Description

(cid:1) Common Property

0

Digit, required. This element will accept any single digit between 0 and 9.

(cid:2) Text: Text displayed on the Button face.

9

Digit or space, optional.

#

Digit or space, optional. Plus (+) and minus (-) signs are allowed.

(cid:1) Common Events

(cid:2) Click: Occurs when the user clicks the control. Default event when this control

L

Letter, required ([a..z] or [A..Z])

is double clicked in the designer.

?

Letter, optional ([a..z] or [A..Z])

,

Thousands placeholder (1,234)

.

Decimal placeholder (0.32)

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Check Boxes

Check Boxes

(cid:1) A control that is either selected or not selected

(cid:1) Common Properties

(cid:2) Checked: Whether or not the CheckBox has been checked. (cid:2) Text: Text displayed to the right of the CheckBox (called the label).

(cid:2) True or false state (cid:2) No restriction on usage

(cid:1) Common Events

(cid:2) CheckedChanged: Occurs whenever the Check property is changed. Default

event when this control is double clicked in the designer.

(cid:2) CheckStateChanged: Occurs whenever the CheckState property is

Result when bold is selected

changed.

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Radio Buttons

Radio Buttons

(cid:1) Common Properties

(cid:1) RadioButton

(cid:2) Checked: Whether the RadioButton is checked. (cid:2) Text: Text displayed to the right of the RadioButton (called the label).

(cid:2) Grouped together (cid:2) Only one can be true (cid:2) Mutually exclusive options

(cid:1) Common Events

(cid:2) Click: Occurs when the control is clicked. (cid:2) CheckedChanged

○ Occurs whenever the Check property changes value. ○ Default event when this control is double clicked in the designer.

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Picture Boxes

Picture Boxes

(cid:1) Used to display graphics

(cid:1) Common Properties

(cid:2) in bitmap, GIF, JPEG, metafile, or icon format.

(cid:2) Image: Image to display in the PictureBox. (cid:2) SizeMode: Enumeration that controls image sizing and positioning.

○ Normal (default) puts image in top-left corner of PictureBox and CenterImage

puts image in middle.

○ StretchImage resizes image to fit in PictureBox. ○ AutoSize resizes PictureBox to hold image.

(cid:1) Common Events

(cid:2) Click:

○ Occurs when the user clicks the control. ○ Default event when this control is double clicked in the designer.

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List Boxes

List Boxes

(cid:1) Common Properties

(cid:1) Use to display a list from which the user can select items.

(cid:2) SelectionMode: Indicate if the list box is to be single-select, multi-select, or

not selectable.

(cid:2) Items: The items of the list box

(cid:2) MultiColumn: Indicate if values should be displayed in columns horizontally.

(cid:2) SelectedIndex: Gets or sets the zero-based index of the currently selected

item.

(cid:2) SelectedIndices: Returns a collection of the indices of all currently selected

items.

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List Boxes

List Boxes

(cid:1) ListBox Common Methods

(cid:1) Common Properties

(cid:2) GetSelected: Takes an index, and returns True if the corresponding item is

(cid:2) SelectedItem: Returns the currently selected item.

selected.

(cid:2) SelectedItems: Returns a collection of the currently selected item(s).

(cid:2) SelectedValue: Returns the value of the member property specified by the

(cid:2) Add: Adds an Item to the list of Items ○ listBox1.Items.Add("One"); ○ listtBox1.Items.Add("Two");

ValueMember property.

(cid:2) RemoveAt: Removes the Item at the specified index within the collection

○ listBox1.Items.RemoveAt(row);

(cid:2) Sorted: Indicates whether items appear in alphabetical order. True causes

alphabetization; default is False.

(cid:2) Clear: Clear to all Items collection

○ listBox1.Items.Clear();

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List Boxes

Checked List Boxes

(cid:1) Extends ListBox by placing a check box at the left of each item.

(cid:1) Common Events

(cid:2) SelectedIndexChanged: Occurs when the value of SelectedIndex

property changes.

(cid:1) Can select more than one object at one time

(cid:1) Can add to, remove from or clear list

(cid:1) Can select multiple items from the list

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Checked List Boxes

Checked List Boxes

(cid:1) CheckedListBox Common Properties

(cid:1) CheckedListBox Common Methods

(cid:2) CheckedItems: The collection of items that are checked. Not the same as the

(cid:2) GetItemChecked: Takes an index and returns true if corresponding item

selected items, which are highlighted (but not necessarily checked).

checked.

(cid:2) CheckedIndices: Returns indices for the items that are checked.

(cid:1) CheckedListBox Common Events

(cid:2) ItemCheck: Occurs when an item is checked or unchecked.

(cid:2) SelectionMode: Can only have values One (allows multiple selection) or None

○ ItemCheckEventArgs Properties

(does not allow multiple selection).

(cid:2) CurrentValue: Whether current item is checked or unchecked. Values Checked,

Unchecked or Indeterminate. (cid:2) Index: Index of item that changed. (cid:2) NewValue: New state of item.

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Combo Boxes

Combo Boxes

(cid:1) Combine TextBox and drop-down list.

(cid:1) Common Properties

(cid:2) Items: Collection of items in the ComboBox control.

(cid:1) Common Properties

(cid:2) MaxDropDownItems: Maximum number of items to display in the drop-down

(cid:2) DropDownStyle: Determines the type of combo box.

list (between 1 and 100). If value is exceeded, a scroll bar appears.

○ Simple means that the text portion is editable and the list portion is always visible. ○ DropDown (the default) means that the text portion is editable but an arrow button

must be clicked to see the list portion.

(cid:2) SelectedIndex: Returns index of currently selected item. If there is no

○ DropDownList means that the text portion is not editable.

currently selected item, -1 is returned.

(cid:2) SelectedItem: Returns the currently selected item.

(cid:2) Sorted: If true, items appear in alphabetical order. Default false.

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Combo Boxes

Date-Time Pickers

(cid:1) DateTimePicker

(cid:1) ComboBox Common Methods

(cid:2) enables the user to select a date and time, and to display that date and time in a

specified format.

(cid:2) Add: Adds an Item to the list of Items ○ comboBox1.Items.Add("One"); ○ comboBox1.Items.Add("Two");

(cid:1) Common Properties

(cid:2) RemoveAt: Removes the Item at the specified index within the collection

(cid:2) CustomFormat: the format string used to format the date and/or time displayed

○ comboBox1.Items.RemoveAt(row);

in the control.

(cid:2) Value: The current date/time value for this control.

(cid:2) Clear: Clear to all Items collection ○ comboBox1.Items.Clear();

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List Views

List View: View Modes

(cid:1) Used to display a collection of items as a grid.

(cid:1) List View can display items in 5 modes:

(cid:2) Large Icon (cid:2) Details (cid:2) Small Icon (cid:2) List (cid:2) Tile

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ListViewItem

List Views

(cid:1) Each item in ListView is a ListViewItem.

(cid:1) Common Properties

(cid:2) Columns: The columns shown in Details View (cid:2) Items: The items in the List View (cid:2) View: Select one of 5 different views that items can be shown in. (cid:2) FullRowSelect: Indicates whether all SubItems are highlighted along with the

item when selected.

(cid:1) Properties of ListViewItem (cid:2) Text: displayed text of the item (cid:2) SubItems: sub-items of the ListViewItem, be shown in Details mode. (cid:2) ImageIndex: index of the image of the item.

(cid:2) SelectedIndex: Gets or sets the zero-based index of the currently selected

item.

(cid:1) Common Events

(cid:2) SelectedIndexChanged: Occurs when the value of SelectedIndex

property changes.

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List View: Ví dụ

Tree Views

(cid:1) Displays nodes hierarchically

(cid:1) Parent nodes have children

(cid:1) The first parent node is called the root

(cid:1) Each node of TreeView is a TreeNode.

Root nodes

Child nodes

Click to collapse node, hiding child nodes

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Tree Views

Tree Views

(cid:1) Common Properties

(cid:1) Common Properties

(cid:2) CheckBoxes: Indicates whether checkboxes appear next to nodes. True

(cid:2) Nodes: Lists the collection of TreeNodes in the control. Contains methods

displays checkboxes. Default is False.

○ Add (adds a TreeNode object), ○ Clear (deletes the entire collection) and ○ Remove (deletes a specific node). Removing a parent node deletes all its children.

(cid:2) ImageList: Indicates the ImageList used to display icons by the nodes.

○ An ImageList is a collection that contains a number of Image objects.

(cid:2) SelectedNode: Currently selected node.

(cid:1) Common Events

(cid:2) AfterSelect: Generated after selected node changes. Default when double-

clicked in designer.

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Tree Nodes

Tree Nodes

(cid:1) Common Properties

(cid:1) Common Properties

(cid:2) Checked: Indicates whether the TreeNode is checked. (CheckBoxes property

(cid:2) LastNode: Specifies the last node in the Nodes collection (i.e., last child in

must be set to True in parent TreeView.)

tree).

(cid:2) FirstNode: Specifies the first node in the Nodes collection (i.e., first child in

(cid:2) NextNode: Next sibling node.

tree).

(cid:2) PrevNode: Indicates the previous sibling node.

(cid:2) FullPath: Indicates the path of the node, starting at the root of the tree.

(cid:2) SelectedImageIndex: Specifies the index of the image to use when the node

(cid:2) ImageIndex: Specifies the index of the image to be shown when the node is

is selected.

deselected.

(cid:2) Text: Specifies the text to display in the TreeView.

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Tree Nodes

Tree View: Ví dụ

(cid:1) Common Methods

(cid:2) Collapse: Collapses a node.

(cid:2) Expand: Expands a node.

(cid:2) ExpandAll: Expands all the children of a node.

(cid:2) GetNodeCount: Returns the number of child nodes.

(cid:2) Remove: Remove current node from the tree view control.

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Ghi chú

Containers

(cid:1) Containers help to organize (layout) controls.

(cid:2) Panel (cid:2) Group Box (cid:2) Tab Control (cid:2) Split Container

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

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Panels

Panel: Ví dụ

(cid:1) Panels are used to group other controls. They can have scrollbars.

Panel

(cid:1) Common Properties

Controls inside Panel

(cid:2) AutoScroll: Whether scrollbars appear when the Panel is too small to hold

its controls. Default is false.

(cid:2) BorderStyle: Border of the Panel. Default is None.

(cid:2) Controls: The controls that the Panel contains.

Panel’s ScrollBar

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Group Boxes

Tab Controls

(cid:1) GroupBoxes are used to group other controls.

(cid:1) Tab Controls are used to group controls into pages.

(cid:1) The GroupBox control is similar to the Panel control;

(cid:1) Each page of TabControl is another container, TabPage.

(cid:2) however, only the GroupBox control displays a caption, and only the Panel

control can have scroll bars.

(cid:1) Common Properties

TabPage

TabControl

(cid:2) Controls: The controls that the GroupBox contains. (cid:2) Text: Text displayed on the top portion of the GroupBox (its caption).

Controls in TabPage

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Tab Controls

Split Containers

(cid:1) Common Properties

(cid:1) Split Containers are used to groups controls to 2 splitted resizable

panels.

(cid:1) Each panel of the SplitContainer is also a Panel.

(cid:2) SelectedIndex: Indicates index of TabPage that is currently selected. (cid:2) SelectedTab: Indicates the TabPage that is currently selected. (cid:2) TabCount: Returns the number of tabs. (cid:2) TabPages: Gets the collection of TabPages within our TabControl.

(cid:1) Common Event

(cid:2) SelectedIndexChanged: Occurs when another TabPage is selected.

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Menu và Toolbar

Menus

(cid:1) MenuStrip

(cid:1) Menus

(cid:2) Display application commands and options grouped by functionality.

(cid:1) Context Menus

(cid:1) Toolbars

(cid:1) Status Bars

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MenuStrip

Menus

(cid:1) Common Properties

Menu

(cid:2) Name: Indicates the name used in code to identify the menu. Usually set

Shortcut key

mnu+text (e.g. mnuFile, mnuNew, mnuOpen,...).

(cid:2) Checked: Whether menu item appears checked. Default false, meaning that

Disabled command

the menu item is not checked.

submenu

(cid:2) Shortcut: Shortcut key for the menu item (i.e. Ctrl + F9 can be equivalent to

clicking a specific item).

Separator bar

Checked menu item

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MenuStrip

Context Menus

(cid:1) Common Properties

(cid:1) ContextMenuStrip

(cid:2) ShowShortcut: If true, shortcut key shown beside menu item text. Default

(cid:2) Display a shortcut menu when the user right-clicks the associated controls.

true.

(cid:2) Text: Text to appear on menu item. To make an Alt access shortcut, precede a

(cid:1) To display shortcut menu of the control

character with & (i.e. &File for File).

(cid:2) sets the ContextMenuStrip property of the control to the name of

ContextMenuStrip menu.

(cid:1) Common Events

(cid:2) Click: Occurs when item is clicked or shortcut key is used. Default when

double-clicked in designer.

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Toolbars

Toolbars

(cid:1) ToolStrip contains buttons which are ToolStripMenuItem(s)

(cid:1) ToolStrip

(cid:2) Provide toolbars and other user interface elements that support many appearance options, and that support overflow and runtime reordering.

with (cid:2) Properties: Text, Image, Checked, DropDownItems (cid:2) Events: Clicked

(cid:1) To add standard toolbars in the designer

(cid:1) Buttons of ToolStrip could be:

(cid:2) Create a ToolStrip control. (cid:2) In the upper right corner of the ToolStrip, click the smart task arrow to display

the ToolStrip Tasks pane.

(cid:2) In the ToolStrip Tasks pane, choose Insert Standard Items

(cid:2) ToolStripButton (cid:2) ToolStripSplitButton (cid:2) ToolStripDropDownButton (cid:2) ToolStripComboBox (cid:2) ToolStripTextBox (cid:2) ToolStripSeperator (cid:2) ToolStripProgressBar

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Status Bars

Custom Controls

(cid:1) StatusStrip

(cid:1) To create controls that abstract away unimportant details and are

tailored for a specific type of data.

(cid:2) Display information to the user about the object being viewed, the object’s

components, or the object’s operations.

(cid:1) To create controls that provide entirely new functionality, or just

combine existing UI elements in a unique way.

(cid:1) To create controls with a distinct original look, or ones that mimic

popular controls in professional applications.

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SubmitButton User Control

Types of Custom Controls

(cid:1) Inherited controls are generally powerful and flexible. (cid:2) choose the existing .NET control that is closest to what we

want to provide.

(cid:1) User controls are the simplest type of control.

(cid:2) They inherit from System.Windows.Forms.UserControl class, and follow a

model of composition.

(cid:2) They combine more than one control in a logical unit (like a group of text boxes

for entering address information).

(cid:1) Owner-drawn controls generally use GDI+ drawing routines to

generate their interfaces from scratch.

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LoginValidation User Control

Một số ví dụ khác về User Control

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Sự kiện Paint

Hàm OnPaint

(cid:1) The Paint event is raised when the control is redrawn.

(cid:1) The base Control class

(cid:2) does not know how a derived control needs to be drawn and (cid:2) does not provide any painting logic in the OnPaint method.

(cid:1) It passes an instance of PaintEventArgs to the method(s) that

class MyCustomButton : Button {

handles the Paint event.

protected override void OnPaint(PaintEventArgs pevent) { // call inherited function: to draw normal button base.OnPaint(pevent); // draw from scratch pevent.Graphics.DrawEllipse(new Pen(Color.Red), 0, 0, Width, Height);

// subscribe to Paint event of button1 this.button1.Paint += new System.Windows.Forms.PaintEventHandler(this.button1_Paint);

}

}

class MyNewButton : Button {

private void button1_Paint(object sender, PaintEventArgs e) {

protected override void OnPaint(PaintEventArgs pevent) {

Control ctrl = sender as Control; Point center = new Point(ctrl.Width / 2, ctrl.Height / 2);

// do not call inherited function // base.OnPaint(pevent); // draw from scratch pevent.Graphics.DrawEllipse(new Pen(Color.Red), 0, 0, Width, Height);

// draw a rectangle at center of button e.Graphics.DrawRectangle(new Pen(Color.Red),

}

}

center.X - 50, center.Y - 15, // X and Y 100, 30 // Width and Height

);

}

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Một số ví dụ về vẽ Controls

Một số ví dụ về giao diện “Luxury”

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Một số ví dụ về giao diện “Luxury”

Ghi chú

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

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Đa luồng

(cid:1) Threading

(cid:1) Control threads

Chương 4

(cid:1) Synchronize between threads

(cid:1) UI thread

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Luồng – Threading

Đa luồng – Multi-threading

(cid:1) Threading

(cid:1) Multithreading

(cid:2) enables a C# program to perform concurrent processing so it can do more than

(cid:2) solves problems with responsiveness and multi-tasking.

one operation at a time.

(cid:1) Multithreading

(cid:1) The System.Threading namespace (in mscorlib.dll) provides

(cid:2) introduces resource sharing and synchronization issues.

classes and interfaces that support multithreaded programming: (cid:2) creating and starting new threads, (cid:2) synchronizing multiple threads, (cid:2) suspending threads, (cid:2) and aborting threads.

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Ưu điểm

Nhược điểm

(cid:1) Communicate over a network, to a Web server, and to a database.

(cid:1) The system consumes memory for the context information required

by processes.

(cid:1) Perform operations that take a large amount of time.

(cid:1) Keeping track of a large number of threads consumes significant

processor time.

(cid:1) Distinguish tasks of varying priority: high-priority thread manages time-critical tasks, and low-priority thread performs other tasks.

(cid:1) Controlling code execution with many threads is complex.

(cid:1) Allow the user interface to remain responsive, while allocating time to

background tasks.

(cid:1) Destroying threads requires knowing what could happen and

handling those issues.

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Lớp Thread

Lớp Thread

(cid:1) Properties

(cid:1) Creates and controls a thread, sets its priority, and gets its status.

(cid:1) Thread is sealed.

(cid:2) ThreadState (cid:2) IsAlive (cid:2) ThreadPriority

(cid:1) Use a ThreadStart delegate to specify the program code executed

(cid:1) Methods

by a thread.

(cid:2) Start(), Resume() (cid:2) Interrupt(), Abort()

(cid:1) Static members

(cid:2) CurrentThread, (cid:2) Sleep()

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ThreadStart delegate

Thread: Ví dụ

(cid:1) Represents the method that executes on the Thread.

using System; using System.Threading; public class ThreadExample {

public static void ThreadProc() {

for (int i = 0; i < 10; i++) {

(cid:1) Delegate declaration:

Console.WriteLine("ThreadProc: {0}", i); Thread.Sleep(100);

}

(cid:2) public delegate void ThreadStart();

} public static void Main() {

(cid:1) The declaration of your callback method must have the same

Console.WriteLine("Main thread: Start a second thread."); Thread t = new Thread(new ThreadStart(ThreadProc)); t.Start();

parameters as the ThreadStart delegate declaration.

for (int i = 0; i < 4; i++) {

Console.WriteLine("Main thread: Do some work."); Thread.Sleep(100);

}

Console.WriteLine("Main thread: Call Join()."); t.Join();

Console.WriteLine("Main thread: Join has returned."); Console.ReadLine();

}

}

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Truyền và nhận thông tin từ thread

Truyền thông tin cho thread

(cid:1) The ThreadStart delegate

(cid:1) Create a class ThreadWithData to hold the data Data and the

(cid:2) has no parameters or return value.

thread method ThreadProc.

(cid:1) User cannot

(cid:1) Create an object of ThreadWithData class with desired Data.

(cid:2) start a thread using a method that takes parameters, or (cid:2) obtain a return value from the method.

(cid:1) Create a thread with ThreadStart delegate “ThreadProc”.

(cid:1) To pass data to a thread

(cid:1) Once ThreadProc is called, access the Data.

(cid:2) create an object to hold the data and the thread method.

(cid:1) To retrieve the results of a thread method

(cid:2) we can use a callback method.

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Truyền thông tin: Ví dụ

Nhận kết quả từ thread

(cid:1) Create a class ThreadWithCallback to hold the delagate ResultHandler and the thread method ThreadProc.

using System; using System.Threading; public class ThreadWithData { private string Data; public ThreadWithData(string data) {

Data = data;

(cid:1) Create an object of ThreadWithCallback class with desired

} public void ThreadProc() {

Callback.

Console.WriteLine("Do work with argument: Hello {0}.", Data);

}

}

public class Example {

(cid:1) Create a thread with ThreadStart delegate “ThreadProc”.

public static void Main() {

ThreadWithData twd = new ThreadWithData("C# World"); Thread t = new Thread(new ThreadStart(twd.ThreadProc)); t.Start();

(cid:1) Once ThreadProc is finished, call the Callback.

Console.WriteLine("Main thread does some work, then waits.");

t.Join(); Console.WriteLine("Independent task has completed."); Console.ReadLine();

}

}

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Nhận kết quả: Ví dụ

Điều khiển các thread

public delegate void ResultHandler(string result); public class ThreadWithCallback {

(cid:1) Pausing a thread

private string Data; private ResultHandler Callback; public ThreadWithCallback(string data, ResultHandler callback) {

Data = data; Callback = callback;

(cid:1) Suspend a thread

} public void ThreadProc() {

(cid:1) Resume a thread

Console.WriteLine("Do work with argument: {0}.", Data); string Result = "Hello " + Data; if (Callback != null) Callback(Result);

}

} public class ExampleCallback {

(cid:1) Stopping a thread

public static void Main() {

ThreadWithCallback twc = new ThreadWithCallback("C# World", resultCallback); Thread t = new Thread(new ThreadStart(twc.ThreadProc)); t.Start(); Console.WriteLine("Main thread does some work, then waits."); t.Join(); Console.WriteLine("Independent task has completed."); Console.ReadLine();

} private static void resultCallback(string result) {

Console.WriteLine("Handle the result '{0}' here...", result);

}

}

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Tạm ngưng một thread

Tạm dừng một thread

(cid:1) We can pause a thread by calling Thread.Suspend.

(cid:1) After a thread has been started, we often want to pause that thread

for a fixed period of time.

(cid:1) When a thread calls Suspend on itself,

(cid:1) Calling Thread.Sleep causes the current thread to immediately

(cid:2) the call blocks until the thread is resumed by another thread.

block for the number of milliseconds.

(cid:1) When one thread calls Suspend on another thread,

(cid:1) One thread cannot call Sleep on another thread.

(cid:2) the call is a non-blocking call that causes the other thread to pause.

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Tạm dừng một thread

Tiếp tục một thread

(cid:1) We can call Suspend many times on a thread.

(cid:1) Calling Thread.Resume

(cid:2) breaks another thread out of the suspend state and (cid:2) causes the thread to resume execution.

(cid:1) A thread cannot be suspended

(cid:2) if it has not been started or if it has stopped.

(cid:1) The thread will resume

(cid:2) regardless of how many times Thread.Suspend was called.

(cid:1) Suspend does not cause a thread to immediately stop execution. (cid:2) The CLR must wait until the thread has reached a safe point before it can

suspend the thread.

(cid:1) The thread resumes execution immediately following the call to

Resume.

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Dừng hẳn thread

Ghi chú

(cid:1) We can block threads in a number of ways:

(cid:2) Thread.Join (cid:2) Thread.Sleep (cid:2) Synchronized object

(cid:1) We can interrupt a waiting thread

(cid:2) by calling Thread.Interrupt on the blocked thread to throw a

ThreadInterruptedException, which breaks the thread out of the blocking call.

(cid:1) Thread.Abort is similar to Thread.Interrupt

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

(cid:2) except that it causes ThreadAbortException.

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Đồng bộ hóa các thread

Đồng bộ hóa

(cid:1) One of the benefits of using multiple threads in an application

(cid:1) Thread synchronization in C# can be accomplished by using:

(cid:2) lock statement

(cid:2) is that each thread executes asynchronously.

(cid:2) Monitor class

(cid:1) Those threads asynchronously access to resources

(cid:2) such as file handles, network connections, and memory must be coordinated.

(cid:2) Synchronization events

(cid:1) They could access the same resource at the same time, each

(cid:2) Mutex class

unaware of the other's actions. (cid:2) The result is unpredictable data corruption.

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Câu lệnh lock

Câu lệnh lock

(cid:1) The lock keyword

(cid:1) The argument provided to the lock keyword must be an object.

(cid:2) can be used to ensure that a block of code runs to completion without

interruption by other threads.

(cid:1) Many types provide a SyncRoot member to use by lock statement.

(cid:1) This is accomplished by obtaining a mutual-exclusion lock

(cid:2) for a given object for the duration of the code block.

public class TestThreading { private Object lockThis = new Object(); public void Function() { lock (lockThis) {

// Access thread-sensitive resources.

}

(cid:1) A lock statement

}

(cid:2) begins with the keyword lock, and (cid:2) followed by a code block.

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Lớp Monitor

Lớp Monitor

(cid:1) Like the lock keyword, monitors prevent blocks of code from

(cid:1) The Enter method

simultaneous execution by multiple threads.

(cid:2) allows one and only one thread to proceed into the following statements; (cid:2) all other threads are blocked until the executing thread calls Exit.

(cid:1) In fact, the lock keyword is implemented with the Monitor class :

System.Object obj = (System.Object)x; System.Threading.Monitor.Enter(obj); try {

(cid:2) lock is more concise, (cid:2) lock insures that the underlying monitor is released, even if the protected code

DoSomething();

throws an exception.

} finally {

System.Threading.Monitor.Exit(obj);

}

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Các sự kiện đồng bộ hóa

Các sự kiện đồng bộ hóa

(cid:1) lock and Monitor

(cid:1) Threads can be suspended

(cid:2) do not allow one thread to communicate an event to another.

(cid:2) by being made to wait on a synchronization event that is un-signaled.

(cid:1) This requires synchronization events,

(cid:1) Threads can be activated

(cid:2) by changing the event state to signaled.

(cid:2) which are objects that have one of two states, signaled and un-signaled, (cid:2) that can be used to activate and suspend threads.

(cid:1) If a thread attempts to wait on an event that is already signaled,

(cid:2) then the thread continues to execute without delay.

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Các sự kiện đồng bộ hóa

Các sự kiện đồng bộ hóa

(cid:1) There are two kinds of synchronization events

(cid:1) Threads can be made to wait on events by calling one of the wait

(cid:2) AutoResetEvent (cid:2) ManualResetEvent

methods (cid:2) System.Threading.WaitHandle.WaitOne

○ causes the thread to wait until a single event becomes signaled,

(cid:1) AutoResetEvent

(cid:2) changes from signaled to un-signaled automatically any time it activates a

(cid:2) System.Threading.WaitHandle.WaitAny

thread.

○ blocks a thread until one or more indicated events become signaled,

(cid:1) ManualResetEvent

(cid:2) System.Threading.WaitHandle.WaitAll

(cid:2) allows any number of threads to be activated by its signaled state, and will only

○ blocks the thread until all of the indicated events become signaled.

revert to an un-signaled state when its Reset method is called.

(cid:1) An event becomes signaled when its Set method is called.

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Lớp Mutex

Đồng bộ hóa: Ví dụ

class ThreadingExample {

(cid:1) A mutex is similar to a monitor;

(cid:2) it prevents the simultaneous execution of a block of code by more than one

static AutoResetEvent autoEvent; static ManualResetEvent manualEvent; static void DoWork() {

thread at a time.

Console.WriteLine("worker thread started, now waiting on event..."); autoEvent.WaitOne(); Console.WriteLine("worker thread reactivated, now exiting...");

} static void DoAnotherWork() {

(cid:1) A Mutex can be used to synchronize threads across processes.

Console.WriteLine("another worker thread started, now waiting on event..."); manualEvent.WaitOne(); Console.WriteLine("another worker thread reactivated, now exiting...");

} static void Main() {

(cid:1) When used for inter-process synchronization, a Mutex is called a

named mutex. (cid:2) It must be given a name so that both applications can access the same Mutex

autoEvent = new AutoResetEvent(false); manualEvent = new ManualResetEvent(true); Console.WriteLine("main thread starting worker thread..."); Thread t = new Thread(DoWork), t2 = new Thread(DoAnotherWork); t.Start(); t2.Start();

object.

Console.WriteLine("main thrad sleeping for 1 second..."); Thread.Sleep(1000); Console.WriteLine("main thread signaling worker thread..."); autoEvent.Set();

}

}

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Mutex: Ví dụ

UI thread

(cid:1) An UI based application is frozen in a long time when it’s

using System; using System.Threading; namespace TestMutex {

class ExampleMutex {

static void Main1() {

Mutex mutex = null; try {

mutex = Mutex.OpenExisting("Our shared mutex");

} catch (System.Threading.WaitHandleCannotBeOpenedException e) {

(cid:2) making a long database operation (cid:2) or calling a long running service (cid:2) or making any network connections (cid:2) or reading a large file from CD drive, etc.

mutex = new Mutex(false, "Our shared mutex");

} while (mutex.WaitOne(1000) == false)

Console.WriteLine("Mutex is own by another program... Try again.");

(cid:1) The reason is that the program has only 1 thread to listen to user

Console.WriteLine("We obtained the mutex..."); for (int i = 0; i < 10; i++) {

operations and do the underlying tasks. (cid:2) When doing the tasks, the thread cannot handle user operations and the UI is

Console.WriteLine("Do some works..."); Thread.Sleep(1000);

frozen.

} mutex.ReleaseMutex(); Console.ReadLine();

}

}

}

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Worker threads

Đồng bộ hóa giao diện

(cid:1) The solution is

(cid:1) Controls in Windows Forms

(cid:2) create “worker” threads to perform the tasks while the UI thread continues

(cid:2) are bound to a specific thread (UI thread) and are not thread safe.

listening to user operations.

(cid:1) If you are calling a control's method from a different thread,

(cid:1) Once the worker threads finished, or they want to update working

(cid:2) you must use one of the control's invoke methods to marshal the call to the

proper thread.

status to the UI (such as progress bar) (cid:2) they could notify the UI thread.

(cid:1) To executes a delegate on the thread that owns the control's

(cid:1) The worker thread cannot call methods of UI controls directly,

(cid:2) they must use UI thread synchronization.

underlying window handle (GUI thread) (cid:2) Control.Invoke() (cid:2) Control.BeginInvoke() and Control.EndInvoke()

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Invoke: Ví dụ

Ghi chú

(cid:1) Control.InvokeRequired

(cid:2) returns a value indicating whether the caller must call an invoke method when

making method calls to the control.

using System; public delegate void ProgressBarUpdater(); public class WorkerThread {

private System.Windows.Forms.ProgressBar ProgressBar; public WorkerThread(System.Windows.Forms.ProgressBar progressBar) {

ProgressBar = progressBar;

} public void ThreadProc() {

for (int i = 0; i < 100; i++) {

Console.WriteLine("we have done {0}% of the task.", i); if (ProgressBar.InvokeRequired) {

ProgressBarUpdater updater = delegate() {

ProgressBar.Value = i;

}; ProgressBar.Invoke(updater);

}

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

}

}

}

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Kết nối mạng

IP Address

(cid:1) .NET defines two classes in the System.Net namespace to handle

(cid:1) IP Addresses

(cid:1) Sockets

various types of IP address information (cid:2) IPAddress: is used to represent a single IP address. (cid:2) IPEndPoint: is used when binding sockets to local addresses, or when

connecting sockets to remote addresses

(cid:1) Connection-Oriented Sockets

(cid:1) .NET also defines System.Net.Dns class for looking up IP

(cid:1) Networking and Multi-threading

addresses from domain (host) name.

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Lớp IPAddress

Lớp IPEndPoint

Method

Method

Description

Equals

Compares two IP addresses.

Create

Description Creates an EndPoint object from a SocketAddress object

HostToNetworkOrder Converts an IP address from host byte order

Equals

Compares two IPEndPoint objects.

to network byte order.

Serialize

IsLoopBack

Creates a SocketAddress instance of the IPEndPoint instance

Indicates whether the IP address is considered the loopback address.

ToString

NetworkToHostOrder Converts an IP address from network byte

Creates a string representation of the IPEndPoint instance

order to host byte order.

Description

Parse

Property Address

Gets or sets the IP address property

Converts a string to an IPAddress instance.

AddressFamily

Gets the IP address family

Port

Gets or sets the TCP or UDP port number

ToString

Converts an IPAddress to a string representation of the dotted decimal format of the IP address.

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Lớp Dns

Ví dụ

using System; using System.Net; class IPEndPointSample {

Method

Description

public static void Main() {

GetHostName

Gets the host name of the local computer.

IPAddress test1 = IPAddress.Parse("192.168.1.1"); IPEndPoint ie = new IPEndPoint(test1, 8000); Console.WriteLine("The IPEndPoint is: {0}", ie.ToString()); Console.WriteLine("The AddressFamily is: {0}", ie.AddressFamily); Console.WriteLine("The address is: {0}, and the port is: {1}\n",

Resolve

ie.Address, ie.Port);

Resolves a DNS host name or IP address to an System.Net.IPHostEntry instance

Console.WriteLine("The min port number is: {0}", IPEndPoint.MinPort); Console.WriteLine("The max port number is: {0}\n", IPEndPoint.MaxPort);

GetHostEntry

Resolves a host name or IP address to an System.Net.IPHostEntry instance.

ie.Port = 80; Console.WriteLine("The changed IPEndPoint value is: {0}", ie.ToString()); SocketAddress sa = ie.Serialize(); Console.WriteLine("The SocketAddress is: {0}", sa.ToString());

}

}

.NET Programming - Nguyễn Đạt Thông 389 .NET Programming - Nguyễn Đạt Thông 390

Tạo một Socket

Sockets

(cid:1) The System.Net.Sockets namespace

SocketType

ProtocolType

Description

(cid:2) contains the classes that provide the actual .NET interface to the low-level

Dgram

Udp

Connectionless communication

Winsock APIs.

Stream

Tcp

Connection-oriented communication

(cid:1) The Socket class

Raw

Icmp

(cid:2) is the core of the System.Net.Sockets namespace.

Internet Control Message Protocol

Raw

Raw

Plain IP packet communication

(cid:1) To construct a Socket, use following constructor

(cid:1) Example

public Socket(AddressFamily addressFamily,

Socket newsock = new Socket(AddressFamily.InterNetwork,

SocketType socketType, ProtocolType protocolType);

SocketType.Stream, ProtocolType.Tcp);

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Thuộc tính của Socket

Connection-Oriented Sockets

(cid:1) Server functions

Property

Description

AddressFamily

Gets the address family of the Socket

(cid:2) Bind() (cid:2) Listen() (cid:2) Accept()

Available

Gets the amount of data that is ready to be read

Blocking

Gets or sets whether the Socket is in blocking mode

(cid:1) Client functions (cid:2) Connect()

Connected

Gets a value that indicates if the Socket is connected to a remote device

LocalEndPoint

Gets the local EndPoint object for the Socket

(cid:1) Server and Client functions

ProtocolType

Gets the protocol type of the Socket

RemoteEndPoint

Gets the remote EndPoint information for the Socket

(cid:2) Send() (cid:2) Receive() (cid:2) Close()

SocketType

Gets the type of the Socket

.NET Programming - Nguyễn Đạt Thông 393 .NET Programming - Nguyễn Đạt Thông 394

Server: Ví dụ

Client: Ví dụ

using System; using System.Net; using System.Net.Sockets; class ListenSample {

public static void Main() {

using System; using System.Net; using System.Net.Sockets; class ConnectSample {

public static void Main() {

IPHostEntry local = Dns.GetHostEntry(Dns.GetHostName()); IPEndPoint iep = new IPEndPoint(local.AddressList[1], 8000); // second address is IPv6

IPAddress host = IPAddress.Parse("192.168.167.87"); IPEndPoint hostep = new IPEndPoint(host, 8000);

Socket newserver = new Socket(AddressFamily.InterNetwork,

Socket sock = new Socket(AddressFamily.InterNetwork,

SocketType.Stream, ProtocolType.Tcp);

SocketType.Stream, ProtocolType.Tcp);

newserver.Bind(iep); newserver.Listen(5);

Console.WriteLine("Connecting to server..."); try {

Console.WriteLine("Listen on {0}. Waiting for clients...",

newserver.LocalEndPoint);

sock.Connect(hostep); Console.WriteLine("Server Connected.");

Socket newclient = newserver.Accept(); Console.WriteLine("New client connected: {0}", newclient.RemoteEndPoint);

} catch (Exception e) {

}

Console.WriteLine("Cannot connect to server: {0}", e.Message);

}

}

}

}

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Giao tiếp Server-Client

Giao tiếp Server-Client

class ConnectSample {

public static void Main() {

class ListenSample {

public static void Main() {

// ... try {

// ... try {

Console.WriteLine("Say hello to server..."); string hello = "Hello from client."; byte[] btHello = System.Text.Encoding.Default.GetBytes(hello); sock.Send(btHello);

Console.WriteLine("Waiting for message from client..."); byte[] btMsg = new byte[1024]; newclient.Receive(btMsg); string msg = System.Text.Encoding.Default.GetString(btMsg); Console.WriteLine("Receive: {0}", msg);

byte[] btReply = new byte[1024]; sock.Receive(btReply); string reply = System.Text.Encoding.Default.GetString(btReply); Console.WriteLine("Reply from server: {0}", reply);

string hello = "Hello from Server."; byte[] btHello = System.Text.Encoding.Default.GetBytes(hello); newclient.Send(btHello);

} catch (Exception e) {

} catch (Exception e) {

Console.WriteLine("Network error: {0}", e.Message);

Console.WriteLine("Network error: {0}", e.Message);

}

}

}

}

}

}

.NET Programming - Nguyễn Đạt Thông 397 .NET Programming - Nguyễn Đạt Thông 398

Lớp TcpClient

Các lớp tiện ích Socket

(cid:1) The methods of the TcpClient class are used to

(cid:1) The .NET Framework provides a simplified interface for easier

network programming.

(cid:2) create client network programs that follow the connection-oriented network

model.

(cid:1) Three helper classes in System.Net.Sockets namespace are

(cid:1) The TcpClient methods mirror those in normal socket

programming (cid:2) but many of the steps are compacted to simplify the programming task.

used for socket programming (cid:2) TcpClient (cid:2) TcpListener (cid:2) UdpClient

TcpClient newclient = new TcpClient("www.isp.net", 8000);

NetworkStream ns = newclient.GetStream(); byte[] outbytes = Encoding.ASCII.GetBytes("Testing"); ns.Write(outbytes, 0, outbytes.Length); byte[] inbytes = new byte[1024]; ns.Read(inbytes, 0, inbytes.Length); string instring = Encoding.ASCII.GetString(inbytes);

ns.Close(); newclient.Close();

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Lớp TcpListener

Lớp UdpClient

(cid:1) The TcpListener class simplifies server programs

(cid:1) For applications that require a connectionless socket

(cid:2) the UdpClient class provides a simple interface to UDP sockets.

(cid:1) After the Start() method

(cid:1) The Receive() method

(cid:2) use either the AcceptSocket() (cid:2) or AcceptTcpClient() method to accept incoming connection attempts.

(cid:2) allows you to receive data on the UDP port.

TcpListener newserver = new TcpListener(9050); newserver.Start();

UdpClient newconn = new UdpClient(8000); IPEndPoint

remoteclient = new IPEndPoint(IPAddress.Any, 0);

byte[] recv = newconn.Receive(ref remoteclient); string data = Encoding.ASCII.GetString(recv);

TcpClient newclient = newserver.AcceptTcpClient(); NetworkStream ns = newclient.GetStream(); byte[] outbytes = Encoding.ASCII.GetBytes("Testing"); ns.Write(outbytes, 0, outbytes.Length); byte[] inbytes = new byte[1024]; ns.Read(inbytes, 0, inbytes.Length); string instring = Encoding.ASCII.GetString(inbytes);

ConsoleWriteLine("From: {0}", remoteclient.ToString()); ConsoleWriteLine(" Data: {0}", data); newconn.Close();

ns.Close(); newclient.Close(); newserver.Stop();

.NET Programming - Nguyễn Đạt Thông 401 .NET Programming - Nguyễn Đạt Thông 402

Đa luồng và kết nối mạng

Đa luồng và kết nối mạng

Main Program

Server

Main Program

Thread

Thread

Thread

Thread

• Create Socket • Bind Socket • Listen on Socket • While {

• accept connection

clientSock

Client Thread

• create thread

• While {

Network

with parameter clientSock

}

• Receive request from clientSock • Send response to

clientSock

}

Client

Client

Client

Client

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Đa luồng và đa kết nối

Đa luồng và đa kết nối

Main Program

Server

Main Program

• Create Socket • Bind Socket • Listen on Socket • While {

Thread

Thread

Thread

Thread

• accept connection

clientSock

Client Thread

• create thread

• While {

• receive request from

with parameter clientSock

clientSock

Network

• send response to

• store clientSock in client list

clientSock

}

• send request to

partner(s) of clientSock

}

Client

Client

Client

Client

.NET Programming - Nguyễn Đạt Thông 405 .NET Programming - Nguyễn Đạt Thông 406

Đa luồng, đa kết nối, và giao diện

Đa luồng, đa kết nối, và giao diện

UI Thread

Server

UI Thread

Listening Thread

Listening Thread

• Start GUI • Start Listening Thread • While {

• Hanlde UI event

Thread

Thread

Thread

Thread

}

• Create Socket • Bind Socket • Listen on Socket • While {

• accept connection

clientSock

Client Thread

• create thread with

Network

• While {

parameter clientSock • store clientSock in

• receive request from

client list

clientSock

}

• send response to

clientSock

Client

Client

Client

Client

• send request to

partner(s) of clientSock

UI Thread

UI Thread

UI Thread

UI Thread

}

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Tóm lược

Tóm lược

(cid:1) How to create threads to do background tasks?

(cid:1) How to create a server to listen to clients?

(cid:1) How to control worker threads?

(cid:1) How to connect to remote servers?

(cid:1) How to pass data and retrieve result from threads?

(cid:1) How to communicate between clients and servers?

(cid:1) How to synchronize between threads?

(cid:1) How to use socket helper classes?

(cid:1) How to create worker threads for UI program?

(cid:1) How to create a multi-threading network server?

.NET Programming - Nguyễn Đạt Thông 409 .NET Programming - Nguyễn Đạt Thông 410

Tham khảo thêm

Tham khảo thêm

(cid:1) Tutorial: Threading

(cid:1) Thread and Threading

http://msdn.microsoft.com/en-us/library/aa645740(v=vs.71).aspx

http://msdn.microsoft.com/en-us/library/aa720724(v=vs.71).aspx

(cid:1) Control.Invoke method

(cid:1) Tutorial: Thread Synchronization

http://msdn.microsoft.com/en-us/library/ms173179(v=vs.80).aspx

http://msdn.microsoft.com/en-us/library/zyzhdc6b.aspx http://msdn.microsoft.com/en-us/library/a1hetckb.aspx

(cid:1) UI thread and Worker thread

http://www.codeproject.com/Articles/81411/Thread-Synchronization-UI-Thread-and-Worker- Thread

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Tham khảo thêm

Ghi chú

(cid:1) How to C# Socket programming

http://csharp.net-informations.com/communications/csharp-socket-programming.htm

(cid:1) C# Network Programming – Richard Blum

http://www.ccse.kfupm.edu.sa/~fazzedin/COURSES/CSP2005/Reading/NetworkProgrammi ng.pdf

(cid:1) WebClient Class

http://msdn.microsoft.com/en-us/library/system.net.webclient(v=vs.80).aspx

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

.NET Programming - Nguyễn Đạt Thông 413 .NET Programming - Nguyễn Đạt Thông 414

ADO .NET

(cid:1) Connections

(cid:1) Commands & Data Readers

Chương 5

(cid:1) Disconnected Data Sets

(cid:1) Database Independent Coding

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ADO .NET

Kết nối cơ sở dữ liệu

(cid:1) ADO.NET provides managed types for database access

(cid:1) Must specify several pieces of information to connect

(cid:2) generic types in System.Data namespace, (cid:2) SQL Server types in System.Data.SqlClient namespace, (cid:2) other data providers also supported.

(cid:2) server (cid:2) database (cid:2) authentication credentials

(cid:1) Exact connection details differ for different providers

.NET Programming - Nguyễn Đạt Thông 417 .NET Programming - Nguyễn Đạt Thông 418

Server và Database

Chứng thực

(cid:1) Use Server parameter to specify server for SQL Server

(cid:1) Two ways to authenticate a client connection for SQL Server

(cid:2) Windows authentication uses Windows user information ○ IntegratedSecurity set to SSPI in connect string.

(cid:2) passed in connect string. (cid:2) use "." or "localhost" to connect to local database.

string connectString = "Server=localhost;...";

string connectString = "Integrated Security=SSPI;...";

(cid:1) Use Database parameter to specify database for SQL Server

(cid:2) SQL Server authentication uses SQL Server user information

(cid:2) passed in connect string

○ UserID and Password passed in connect string.

string connectString = "User ID=Joe; Password=lobster;...";

string connectString = "Database=pubs;...";

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Mở một kết nối

Ngắt kết nối

(cid:1) Close SqlConnection when finished.

Application

SqlConnection

Database

(cid:2) can call either Close() or Dispose() method (cid:2) typical to place call in finally block or using statement.

(cid:1) Use System.Data.SqlClient.SqlConnection to connect to

static void Main() {

System.Data.SqlClient.SqlConnection connection = null; try {

SQL Server (cid:2) create object (cid:2) specify connect string

//... // open connection connection.Open(); //...

} finally {

○ can pass to constructor ○ can set after creation using ConnectionString property.

// close connection connection.Dispose();

}

(cid:1) Call Open() method

}

string cs = "server=.;Integrated Security=SSPI;database=pubs";

System.Data.SqlClient.SqlConnection connection =

new System.Data.SqlClient.SqlConnection(cs);

connection.Open();

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ExecuteReader

Commands và Readers

ExecuteReader

Application

SqlCommand

SqlConnection

Database

Application

Database

Sql Command

Sql Connection

SqlDataReader

(cid:1) SqlCommand is used to execute a command

(cid:1) Use ExecuteReader() when result set expected

(cid:2) must specify command text ○ can pass to constructor ○ can set after creation using CommandText property

(cid:2) must specify connection to use

(cid:2) returned data placed in SqlDataReader object (cid:2) reader provides forward-only access to data (cid:2) multiple results supported using NextResult (cid:2) throws Exception if command fails

○ can pass to constructor ○ can set after creation using Connection property

System.Data.SqlClient.SqlConnection connection =

new SqlConnection(/.../);

string text = "select * from authors"; System.Data.SqlClient.SqlConnection connection =

new System.Data.SqlClient.SqlConnection(/.../);

System.Data.SqlClient.SqlCommand command =

new System.Data.SqlClient.SqlCommand(text, connection);

// ... string text = "select * from authors"; // create command System.Data.SqlClient.SqlCommand command =

// ... System.Data.SqlClient.SqlDataReader reader = // capture returned data

new System.Data.SqlClient.SqlCommand(text, connection);

command.ExecuteReader(); // execute command

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SqlDataReader

SqlDataReader

(cid:1) Call Close() when finished with SqlDataReader

(cid:1) Two main ways to access rows of result set

(cid:2) use foreach to traverse rows of IDataRecord objects (cid:2) use while loop with Read to manually advance through rows

(cid:2) releases connection (which can then be reused) (cid:2) can not access contained data after closing.

string text = "select * from authors";

System.Data.SqlClient.SqlConnection connection =

(cid:1) Three main ways to access columns of a row

new System.Data.SqlClient.SqlConnection(/.../);

System.Data.SqlClient.SqlCommand command =

new System.Data.SqlClient.SqlCommand(text, connection);

// ... System.Data.SqlClient.SqlDataReader reader = command.ExecuteReader();

(cid:2) index by column ordinal or name (cid:2) pass column index to getXXX methods (cid:2) use for loop with FieldCount to access each column in turn

// loop through rows while (reader.Read()) {

// ... // close reader when finished reader.Close();

// access data in row using indexers string last = (string)reader["au_lname"]; string first = (string)reader[2];

// access data in row using GetXXX methods string zip = reader.GetString(7); // ...

}

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ExecuteNonQuery

Store Procedures

ExecuteNonQuery

(cid:1) SqlCommand is used to execute stored procedure

Application

Database

Sql Command

Sql Connection

int

(cid:1) ExecuteNonQuery is used when no data will be returned

(cid:2) set CommandType property to StoredProcedure (cid:2) set CommandText property to procedure name (cid:2) pass parameters in Parameters collection (cid:2) call ExecuteReader

(cid:2) returns an int specifying number of rows affected

System.Data.SqlClient.SqlCommand command =

new System.Data.SqlClient.SqlCommand("byroyalty", connection);

string text = "insert into authors "

// set command type to 'StoreProcedure' command.CommandType = System.Data.CommandType.StoredProcedure;

+ "(au_id, au_lname, au_fname, contract) values " + "('111-11-1111', 'Adams', 'Mark', 1)";

System.Data.SqlClient.SqlCommand command =

// set parameters for store procedure command.Parameters.Add("@percentage", System.Data.SqlDbType.Int); command.Parameters["@percentage"].Value = 50;

new System.Data.SqlClient.SqlCommand(text, connection);

// execute the store procedure reader = command.ExecuteReader();

// execute command int rowsAffected = command.ExecuteNonQuery();

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DataSet & DataTable

Dữ liệu “Disconnected”

(cid:1) DataSet class models disconnected data set

(cid:1) Disconnected data models in-memory cache of data

(cid:2) has collection property of DataTable objects

(cid:2) tables, relations, rows, columns etc. (cid:2) disconnected and independent of data source.

(cid:1) DataTable is in-memory model of a table

(cid:2) has rows, columns, etc.

DataSet

Customer Name Customer Id

public class DataSet // ... {

Tables

Ann

0

Bob

1

// tables in DataSet public System.Data.DataTableCollection Tables { get; } // ...

}

Customer Id Balance

Rating

public class DataTable // ... {

0

5000

2

Rows { get;}

1

750

5

// rows and columns currently in DataTable public System.Data.DataRowCollection public System.Data.DataColumnCollection Columns{ get;} // ...

}

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DataRow & DataColumn

Phát sinh DataSet

(cid:1) DataRow is in-memory model of row inside DataTable

(cid:1) Two main ways to create DataSet

(cid:2) several ways to access column data (cid:2) rows are generated by tables, not created directly

(cid:2) fill from existing data source such as database ○ use DataAdapter and its Fill() method (cid:2) manually define structure and fill with data

(cid:1) DataColumn models column of DataTable

string text = "select * from authors"; System.Data.SqlClient.SqlConnection conn; // ...

(cid:2) specify name and data type when creating

// create adapter System.Data.SqlClient.SqlDataAdapter adapter =

public class DataRow // ... {

new System.Data.SqlClient.SqlDataAdapter(text, conn);

// create DataSet System.Data.DataSet authors = new System.Data.DataSet();

public object this[string colName] { get; set;} public object this[int colIndex] { get; set;} public object[] ItemArray { get; set;} // ...

// use adapter to fill DataSet adapter.Fill(authors);

} public class DataColumn // ... {

public DataColumn(string name, Type type); // ...

}

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Duyệt DataSet

Tự tạo một DataSet

(cid:1) DataSet three levels of data inside

(cid:1) Manually create DataSet (cid:2) create DataSet object (cid:2) create tables and add to set

(cid:2) set of contained tables (cid:2) rows in each table (cid:2) column values in each row

(cid:1) Manually create DataTable

// traverse DataSet foreach(System.Data.DataTable table in authors.Tables) { foreach (System.Data.DataRow row in table.Rows) { foreach (object data in row.ItemArray) {

// process column value

}

}

}

(cid:2) define table structure (cid:2) create rows, add rows to tables, fill with data // create a table and define its columns System.Data.DataTable customers = new System.Data.DataTable("Customers"); customers.Columns.Add("Name", typeof(string)); customers.Columns.Add("Id", typeof(Int32)); // create a row and add to table System.Data.DataRow row = customers.NewRow(); row[0] = "Ann"; row[1] = 0; customers.Rows.Add(row); // create DataSet and add table to set System.Data.DataSet data = new System.Data.DataSet(); data.Tables.Add(customers);

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Cập nhật cơ sở dữ liệu

Độc lập với các hệ cơ sở dữ liệu

(cid:1) Update database after changing DataSet

IDbConnection

IDbCommand

IDataReader

IDbDataAdapter

(cid:2) use SqlCommandBuilder to create needed SQL commands (cid:2) use Update method of DataAdapter to send changes

SqlConnection

SqlCommand

SqlDataReader

SqlDataAdapter

System.Data.SqlClient

string text = "select * from authors"; System.Data.SqlClient.SqlConnection conn; // ... // create adapter System.Data.SqlClient.SqlDataAdapter adapter =

new System.Data.SqlClient.SqlDataAdapter(text, conn);

// create DataSet System.Data.DataSet authors = new System.Data.DataSet();

OracleConnection

OracleCommand

OracleDataReader

OracleDataAdapter

// use adapter to fill DataSet adapter.Fill(authors, "authors");

System.Data.OracleClient

// modify DataSet authors.Tables[0].Rows[4][2] = "Bob";

MySqlDataAdapter

MySqlConnection

MySqlCommand

MySqlDataReader

// attach builder System.Data.SqlClient.SqlCommandBuilder b =

MySql.Data.MySqlClient

new System.Data.SqlClient.SqlCommandBuilder(adapter);

// update database adapter.Update(authors, "authors");

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Tóm lược

Tham khảo thêm

(cid:1) How to connect to database using connection?

(cid:1) Introduction to ADO.NET

http://csharp-station.com/Tutorial/AdoDotNet/Lesson01

(cid:1) How to execute a SQL query?

(cid:1) Reading Data with the SqlDataReader http://csharp-station.com/Tutorial/AdoDotNet/Lesson04

(cid:1) How to fetch data from Database?

(cid:1) Working with Disconnected Data

(cid:1) How to update data to Database?

http://csharp-station.com/Tutorial/AdoDotNet/Lesson05

(cid:1) How to use independent coding of ADO .NET?

(cid:1) Using Stored Procedures

http://csharp-station.com/Tutorial/AdoDotNet/Lesson07

.NET Programming - Nguyễn Đạt Thông 437 .NET Programming - Nguyễn Đạt Thông 438

Tham khảo thêm

Ghi chú

(cid:1) System.Data.OracleClient Namespace

http://msdn.microsoft.com/en-us/library/347d2380(v=vs.90).aspx

(cid:1) MySQL Connector/Net

http://dev.mysql.com/doc/refman/5.5/en/connector-net.html

(cid:1) Connect C# to MySQL

http://www.codeproject.com/Articles/43438/Connect-C-to-MySQL

(cid:1) Connection strings for SQL Server

http://www.connectionstrings.com/sql-server-2012

………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………

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110

Bài giảng NET programming (2014) - Nguyễn Đạt Thông

Chủ đề:

Kiến trúc phần mềm

2/19/2014

Nội dung

Tổng quan về .NET Framework

Chương 1

1

2/19/2014

.NET Framework là gì?

Mục tiêu của .NET Framework

Mục tiêu của .NET Framework

Các dịch vụ của .NET Framework

2

2/19/2014

Kiến trúc .NET Framework

Common Language Runtime (CLR)

Các thành phần của CLR

Common Type System (CTS)

3

2/19/2014

Intermediate Language (IL)

Just-In-Time (JIT) Compiler

Garbage Collector (GC)

Các ứng dụng .NET

4

2/19/2014

Base Class Library

Base Class Library

Standardized

Non-standardized

Common Language Infrastructure (CLI)

CLI

Implementation

Description

Microsoft Silverlight

Microsoft Compact Framework

Microsoft XNA

Mono Project

DotGNU

Rotor

5

2/19/2014

Assembly

Assembly

Assembly

Assembly

6

2/19/2014

Ghi chú

Tổng quan về MS Visual Studio .NET

Visual Studio .NET

Visual Studio .NET

7

2/19/2014

Tính năng của Visual Studio .NET

Trình soạn thảo

Debugger

Designer

8

2/19/2014

Solution

Solution và Project

Tạo một Solution mới

Solution Files

9

2/19/2014

Công cụ Solution Explorer

Project

Tạo một Project mới

Một số Templates thông dụng

Template

More Information

10

2/19/2014

Các thành phần của Project

Thêm “Reference” vào Project

Thêm thành phần vào Project

Configuration

11