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Lecture Windows programming: Chapter 8 - Châu Thị Bảo Hà
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Lecture Windows programming - Chapter 8 introduce to the files and streams. In this chapter you will be learn contents: Files and Streams overview, IO namespace and its classes, serialization.
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Nội dung Text: Lecture Windows programming: Chapter 8 - Châu Thị Bảo Hà
- Files & Streams
Chapter 8
Ebook: Beginning Visual C# 2010, chapter 21
Reference: C# How to Program, chapter 17
- Contents
Files and Streams overview
IO namespace and its classes
Serialization
- Files and Streams
Files and Streams
C# views each file as a sequential stream of bytes
each file ends either with:
an end-of-file marker
specific byte number
recorded in a system-maintained administrative data structure
When a file is opened, an object is created and a stream is
associated with the object when a file is opened
two types of streams
output
input
- Contents
Files and Streams
IO namespace and its classes
Serialization
- IO namespace and its classes
Class Description
Stream Provides a view of the sequence of bytes
File Provides static methods for creating and manipulating files
FileSystemIn Contains methods that are common to file and directory
fo manipulation
Directory Provides methods for creating, moving and enumerating
through directories and sub-directories
DirectoryInfo Provides instance methods for creating, moving and
enumerating directories and sub-directories
TextReader Represents a reader that can read a sequence of
characters
TextWriter Represents a writer that can write a sequence of
characters
BinaryReade Reads primitive data types as binary values in a specific
r encoding
BinaryWriter Writes primitive types in binary to a stream and supports
- Stream classes
An abstract class from which different classes are
derived
MemoryStream
used to read and write data to memory
BufferedStream
used to read and write to the buffer
FileStream
used to perform read and write operations on files
NetworkStream
used to send and receive data across the network
CryptoStream
used to link the stream of data to any cryptography object for
the purpose of encrypting the data
- FileStream class constructors
Constructors Description
FileStream(string Takes in the path of the file to be
FilePath, FileMode) read from or written to and any one
of the FileMode enumerator values
as its arguments
FileStream(string Takes in the path of the file to be
FilePath, FileMode, read from or written to, any one of
FileAccess) the FileMode enumerator values
and FileAccess enumerator values
as it arguments
- Enumerators used with FileStream class
FileMode Enumerators FileAccess
Append Enumerators
Create Read
CreateNew Write
Open ReadWrite
OpenOrCreate
Truncate
- Directory and File classes
The directory class contains static methods that help
in handling directories and subdirectories
The file class contains static methods that help in
handling files
it also helps in the creation of FileStream class
- File methods
Methods Description
Copy( string Used to copy the contents of a source file to a
SourcePath, string destination file in the specified path. If the
DestinationPath ); destination file does not exist, a new file is
created with the specified name in the
specified path
Create( string Path ) Used to create a file with the specified name
in the specified path
Delete( string Path ) Used to delete a file from a specified path
Exists( string Path ) Used to verify whether a file with the specified
name exists in the specified path. It returns a
Boolean value
Move( string Used to move the specified file from the
SourcePath, string source location to the destination location
DestinationPath )
- Directory methods
Methods Description
CreateDirectory (String Creates all the directories in the specified
Path) path
Delete( string Path ) Deletes an empty directory from a
specified path
Exists( string Path ) Checks whether the given path refers to
an existing directory on disk
Move( string Used to move the specified file from the
SourceFilePath, string source location to the destination location
DestinationFilePath )
GetCurrentDirectory() Returns the current working directory
GetDirectories ( string Gets the names of subdirectories
Path)
GetFiles ( string Path) Gets the names of files in a specified
directory
- Example of Directory and File
using System;
using System.IO;
class DirectoryDemo
{
static void Main(string[] args)
{
Directory.CreateDirectory ("Testdir");
File.Copy ("D:\\abc.txt", "Testdir\\abc.txt");
Console.WriteLine("File Content Copied");
}
}
- Example of Directory and File
void CreateFile() {
string path = @"c:\temp\MyTest.txt";
if ( Directory.Exists( @"c:\temp" ) ) {
// create and save file…
}
}
void ReadFile() {
string path = @"c:\temp\MyTest.txt";
if ( File.Exists( path ) ) {
// read file…
}
}
- TextWriter class
It is an abstract base class for classes that can be
used to write sequential characters
The StreamWriter and StringWriter classes are two
of the derived classes of the TextWriter class
the StreamWriter writes characters to a stream in a
specified encoding
the StringWriter class is used to write data to a string
- StreamWriter methods
Method Description
Write() Used to write a character from the
stream and move the current position to
the next character
WriteLine() Writes a sequence of a line of characters
to the stream. It adds a line terminator to
mark the end of the string
- StreamWriter example
static void Main(string[] args) {
string path = @"d:\myFile\TestFile.txt";
if (Directory.Exists(path.Substring(0, path.LastIndexOf(@"\")))) {
StreamWriter sw = new StreamWriter(path);
// Add some text to the file
sw.Write("This is the ");
sw.WriteLine("header for the file.");
sw.WriteLine(" ---------------------- ");
sw.Write("The date is: ");
sw.WriteLine(DateTime.Now);
sw.Flush();
sw.Close();
Console.Write("Write file success");
}
else
Console.Write("Can not create file. The directory not exists.");
}
- TextReader class
It is an abstract base class for classes that can be
used to read a sequential series of characters
the StreamReader and StringReader classes are two
of the derived classes of the TextReader class
the StreamReader reads a character in a byte stream and
converts it to the specified encoding
the StringReader class is used to read data from an input
string
- StreamReader methods
Methods Description
Read() Used to read a character from the byte
stream and move the current position to
the next character
ReadLine() Reads a sequence of, or a line of
character from the byte stream and
outputs a string data
ReadToEnd() Used to read the byte stream from the
current position in the stream to the end of
the stream
- StreamReader example
static void Main(string[] args)
{
string path = @"d:\myFile\TestFile.txt";
if (File.Exists(path))
{
StreamReader sr = File.OpenText(path);
String input;
while ((input = sr.ReadLine()) != null)
{
Console.WriteLine(input);
}
sr.Close();
}
else
Console.Write("Can not read the file. The file not exists.");
}
- BinaryWriter class
It is used for writing binary data from a C# variable to
a specified stream
The most commonly used methods of this class are
Close() and Write() methods
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