PHP and MySQL by Example- P5

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PHP and MySQL by Example- P5

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  1. Explanation 1 The  HTML  form  is  started  here.  Its  action  calls  the  script  form.php. 2 The  PHP  script  is  started  here.  It  will  process  the  form  input. 3 If  the  form  has  been  submitted,  the  value  $_POST['submit']  will  be  set. 4 The  $_POST  array  contains  the  text  that  the  user  typed  in  the  text  area  box,   named  story.  (See  Chapter  10,  “More  on  PHP  Forms,”  for  more  information  on   the  $_POST  array.)  For  now,  $input  contains  the  input  typed  by  the  user.  See   Figure  6.36. 5 The  stripslashes()  function  removes  the  slashes  that  were  added  by   addslashes(),  the  default  behavior  when  the  magic_quotes_gpc  directive  has   been  turned  on  in  the  php.ini  file.   Figure 6.36. The user fills in a form. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  2. Figure 6.37. After the form in Figure 6.36 is submitted. Output of Example 6.36.       6.2.15. Working with HTML Special Characters Like all languages, HTML has certain characters that have special significance and those characters are represented by HTML entities, special symbols starting with an ampersand and terminated with a semicolon; for example, the < and > symbols are written as &lt; and &gt;. If the user enters text that contains these HTML characters (see Table 6.14) when filling out a form, you can use the htmlspecialchars() function to convert the most common special characters to their respective HTML entities. If you require all HTML character entities to be translated, use htmlentities() shown in the next section. Table 6.14. HTML Special Character Functions Function What  It  Does htmlspecialchars_decode() Converts  special  HTML  entities  back  to  characters htmlspecialchars() Converts  special  characters  to  HTML  entities   The htmlspecialchars() Function The htmlspecialchars() function converts special characters (shown in Table 6.15) to HTML entities. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  3. Table 6.15. Conversion of Special Characters Character  Before The  HTML  Entity &  (ampersand) &amp; "  (double  quote) &quot;  when  ENT_NOQUOTES  is  not  set '  (single  quote) &#039;  only  when  ENT_QUOTES  is  set <  (less  than) &lt; >  (greater  than) &gt;   Format string htmlspecialchars (string string [, int quote_style [, string charset]])   Example: $text = "Isn't the
  4. 2 echo "Original: $text"; 3 echo "Modified: ", htmlspecialchars($text), ""; ?> Explanation 1 The  variable,  $text,  is  assigned  a  string  containing  some  characters   considered  special  when  rendered  by  the  HTML  interpreter;  they  are  the  <  and   &  characters. 2 When  this  string  is  viewed  in  the  browser,  the  HTML  interpreter  sees  the  <  as   an  opening  tag  symbol  followed  by  an  irrelevant  HTML  element.  Nothing  is   displayed  other  than  the  next  opening  <  and  the  closing  >. 3 The  htmlspecialchars()  function  creates  HTML  entities  out  of  the  <  and  &  so   that  the  browser  can  display  text.  Note  that  the  source  page  (see  Figure  6.39)   for  the  Web  page  shows  that  these  entitities  are  now  part  of  the  page. Figure 6.38. Converting special characters to HTML entities. Output from Example 6.37.   Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  5. Figure 6.39. Viewing the source page in the browser.       The htmlentities() Function The htmlentities() function converts all applicable characters to their HTML entities equivalents. Format string htmlentities (string string [, int quote_style [, string charset]])   Example: $string = "5¢ won't get you much at the café Française!"; echo htmlentities($string, ENT_COMPAT); // Returns: 5&#162 won't get you much at the caf&egrave; Fran&ccedil;aise! Table 6.17. Supported Character Sets Charset Aliases Description ISO-­‐8859-­‐ ISO8859-­‐1 Western  European,  Latin-­‐1. 1 ISO-­‐8859-­‐ ISO8859-­‐15 Western  European,  Latin-­‐9.  Adds  the  Euro  sign,  French   15 and  Finnish  letters  missing  in  Latin-­‐1  (ISO-­‐8859-­‐1). UTF-­‐8   ASCII-­‐compatible  multibyte  8-­‐bit  Unicode. cp866 ibm866,  866 DOS-­‐specific  Cyrillic  charset.  This  charset  is  supported  in   4.3.2. cp1251 Windows-­‐1251,   Windows-­‐specific  Cyrillic  charset.  This  charset  is   win-­‐1251,  1251 supported  in  4.3.2. cp1252 Windows-­‐1252,   Windows-­‐specific  charset  for  Western  Europe. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  6. Table 6.17. Supported Character Sets Charset Aliases Description 1252 KOI8-­‐R koi8-­‐ru,  koi8r Russian.  This  charset  is  supported  in  4.3.2. BIG5 950 Traditional  Chinese,  mainly  used  in  Taiwan. GB2312 936 Simplified  Chinese,  national  standard  character  set. BIG5-­‐   Big5  with  Hong  Kong  extensions,  Traditional  Chinese. HKSCS Shift_JIS SJIS,  932 Japanese. EUC-­‐JP EUCJP Japanese. 6.3. Other String Functions This chapter focused on some of the most useful string functions, but PHP provides other useful string functions, as shown in Table 6.18. Table 6.18. PHP Functions Function What  It  Does addcslashes Quotes  string  with  slashes  in  a  C  style. addslashes Quotes  string  with  slashes. bin2hex Converts  binary  data  into  hexadecimal  representation. chop Alias  of  rtrim(). chr Returns  a  specific  character. chunk_split Splits  a  string  into  smaller  chunks. convert_cyr_string Converts  from  one  Cyrillic  character  set  to  another. convert_uudecode Decodes  a  uuencoded  string. convert_uuencode Uuencodes  a  string. count_chars Returns  information  about  characters  used  in  a  string. crc32 Calculates  the  crc32  polynomial  of  a  string. crypt One-­‐way  string  encryption  (hashing). Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  7. Table 6.18. PHP Functions Function What  It  Does echo Outputs  one  or  more  strings. explode Splits  a  string  by  string. fprintf Writes  a  formatted  string  to  a  stream. get_html_translation_table Returns  the  translation  table  used  by  htmlspecialchars()   and  htmlentities(). hebrev Converts  logical  Hebrew  text  to  visual  text. hebrevc Converts  logical  Hebrew  text  to  visual  text  with  newline   conversion. html_entity_decode Converts  all  HTML  entities  to  their  applicable  characters. htmlentities Converts  all  applicable  characters  to  HTML  entities. htmlspecialchars_decode Converts  special  HTML  entities  back  to  characters. htmlspecialchars Converts  special  characters  to  HTML  entities. implode Joins  array  elements  with  a  string. join Alias  of  implode(). levenshtein Calculates  Levenshtein  distance  between  two  strings. localeconv Gets  numeric  formatting  information. ltrim Strips  whitespace  (or  other  characters)  from  the  beginning   of  a  string. md5_file Calculates  the  md5  hash  of  a  given  file. md5 Calculates  the  md5  hash  of  a  string. metaphone Calculates  the  metaphone  key  of  a  string. money_format Formats  a  number  as  a  currency  string. nl_langinfo Query  language  and  locale  information. nl2br Inserts  HTML  line  breaks  before  all  newlines  in  a  string. number_format Formats  a  number  with  grouped  thousands. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  8. Table 6.18. PHP Functions Function What  It  Does ord Returns  ASCII  value  of  character. parse_str Parses  the  string  into  variables. print Outputs  a  string. printf Outputs  a  formatted  string. quoted_printable_decode Converts  a  quoted-­‐printable  string  to  an  8-­‐bit  string. quotemeta Quotes  metacharacters. rtrim Strips  whitespace  (or  other  characters)  from  the  end  of  a   string. setlocale Sets  locale  information. sha1_file Calculates  the  sha1  hash  of  a  file. sha1 Calculates  the  sha1  hash  of  a  string. similar_text Calculates  the  similarity  between  two  strings. soundex Calculates  the  soundex  key  of  a  string. sprintf Returns  a  formatted  string. sscanf Parses  input  from  a  string  according  to  a  format. str_ireplace Case-­‐insensitive  version  of  str_replace(). str_pad Pads  a  string  to  a  certain  length  with  another  string. str_repeat Repeats  a  string. str_replace Replaces  all  occurrences  of  the  search  string  with  the   replacement  string. str_rot13 Performs  the  rot13  encoding  on  a  string.  Shifts  every  alpha   character  13  places  in  the  alphabet. str_shuffle Randomly  shuffles  a  string. str_split Converts  a  string  to  an  array. str_word_count Returns  information  about  words  used  in  a  string. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  9. Table 6.18. PHP Functions Function What  It  Does strcasecmp Binary-­‐safe  case-­‐insensitive  string  comparison. strchr Alias  of  strstr(). strcmp Binary-­‐safe  string  comparison. strcoll Locale-­‐based  string  comparison. strcspn Finds  length  of  initial  segment  not  matching  mask. strip_tags Strips  HTML  and  PHP  tags  from  a  string. stripcslashes Unquotes  string  quoted  with  addcslashes(). stripos Finds  position  of  first  occurrence  of  a  case-­‐insensitive  string. stripslashes Unquotes  string  quoted  with  addslashes(). stristr Case-­‐insensitive  strstr(). strlen Gets  string  length. strnatcasecmp Case-­‐insensitive  string  comparisons  using  a  “natural  order”   algorithm. strnatcmp String  comparisons  using  a  “natural  order”  algorithm. strncasecmp Binary-­‐safe  case-­‐insensitive  string  comparison  of  the  first  n   characters. strncmp Binary-­‐safe  string  comparison  of  the  first  n  characters. strpbrk Searches  a  string  for  any  of  a  set  of  characters. strpos Finds  position  of  first  occurrence  of  a  string. strrchr Finds  the  last  occurrence  of  a  character  in  a  string. strrev Reverses  a  string. strripos Finds  position  of  last  occurrence  of  a  case-­‐insensitive  string   in  a  string. strrpos Finds  position  of  last  occurrence  of  a  character  in  a  string. strspn Finds  length  of  initial  segment  matching  mask. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  10. Table 6.18. PHP Functions Function What  It  Does strstr Finds  first  occurrence  of  a  string. strtok Tokenizes  string. strtolower Makes  a  string  lowercase. strtoupper Makes  a  string  uppercase. strtr Translates  certain  characters. substr_compare Binary-­‐safe  optionally  case-­‐insensitive  comparison  of  two   strings  from  an  offset,  up  to  length  characters. substr_count Counts  the  number  of  substring  occurrences. substr_replace Replaces  text  within  a  portion  of  a  string. substr Returns  part  of  a  string. trim Strips  whitespace  (or  other  characters)  from  the  beginning   and  end  of  a  string. ucfirst Makes  a  string’s  first  character  uppercase. ucwords Uppercases  the  first  character  of  each  word  in  a  string. vfprintf Writes  a  formatted  string  to  a  stream. vprintf Outputs  a  formatted  string. vsprintf Returns  a  formatted  string. wordwrap Wraps  a  string  to  a  given  number  of  characters  using  a  string   break  character. 6.4. Chapter Summary 6.4.1. What You Should Know Now that you have finished this chapter you should be able to answer the following questions: 1. What  is  a  string? 2. When  do  you  use  double  quotes  or  single  quotes? 3. What  are  escape  characters? Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  11. 4. Define  whitespace. 5. What  functions  let  you  format  strings? 6. How  can  you  get  the  length  of  a  string  and  count  the  characters  in  a  substring? 7. What  functions  compare  strings?  Are  strings  case  sensitive  when  they  are   compared? 8. What  functions  find  similarities  in  strings? 9. How  do  you  find  a  position  in  a  string?  What  functions  let  you  find  a  specified   position  in  a  string? 10. What  is  a  substring?  What  functions  extract  parts  of  a  string? 11. What  is  meant  by  “trimming”  and  “padding”? 12. What  functions  are  used  for  searching  and  replacing  within  strings? 13. What  are  special  characters? 14. What  are  HTML  entities? 15. How  do  you  force  breaks  in  a  string? 16. What  functions  deal  with  homophones? 6.4.2. What’s Next? Chapter 7, “Conditionals and Loops,” covers PHP conditional statements (if/else/elseif, switch) and loops (while, for, foreach). Chapter 6 Lab 1. Assign  your  e-­‐mail  address  to  a  string.  Use  PHP  string  functions  to  get  the  user   name  and  the  domain  name. 2. Create  the  following  string:     $string = " mary jones lives in santa cruz, california at 22 ocean drive."   a. Find the number of characters in the string. b. Capitalize all the letters in the string. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  12. c. Now make all the characters lowercase. d. Use the substr() function to print Santa Cruz, California. The first letter in each word will be in uppercase. e. Use the substr() function to print Mary’s street address. f. Trim out the whitespace at the beginning of the string. g. Find the index position of California. h. Replace Santa Cruz with Los Altos (case insensitive). i. Find the number of words in the string. 3. Use  the  strcmp()  function  to  compare  the  following  two  strings,  first  comparing   $str1  and  $str2,  then  comparing  $str2  and  $str1.  Explain  the  value  that  is   returned  from  the  function.     $str1="Pear"; $str2="Pearson";   What value is returned from strcmp() if you compare $str1 to $str1? 4. Write  a  script  to  generate  a  4-­‐letter  random  password  with  uppercase,  lowercase,   and  numeric  characters.  Store  the  password  as  a  variable  and  display  it.Start  with:     $str = "abcdefghijklmnopqrlsuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";   Hint: Try str_shuffle(). 5. Create  a  scalar  variable  to  contain  a  money  amount  of  155000000.  Use  the   number_format()  function  to  display  the  number  as  U.S.  dollars  with  a  comma   separator  and  decimal  point.  Now  display  the  same  number  in  Euros  as  it  would   be  formatted  in  Western  Europe  and  place  the  Euro  symbol  before  the  number   (&#8364).   Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  13. Chapter 7. Conditionals and Loops 7.1. Control Structures, Blocks, and Compound Statements Figure 7.1 shows a flow chart. A flow chart is defined as a pictorial representation of how to plan the stages of a project. It helps to visualize what decisions need to be made to accomplish a task. People control their lives by making decisions, and so do programs. In fact, acccording to computer science books, a good language allows you to control the flow of your program in three ways: • Execute a sequence of statements. • Based on a test, branch to an alternative sequence of statements. • Repeat a sequence of statements until some condition is met. Figure 7.1. A flow chart.   Well, then, PHP must be a good language. We’ve already used programs that execute a sequence of statements, one after another. Now we examine the branching and looping control structures that allow the flow of the program’s control to change depending on some conditional expression. The decision-making constructs (if, if/else, if/else if) contain a control expression that determines whether a block of statements will be executed. The looping constructs (while, for) allow the program to repetitively execute a statement block until some condition is satisfied. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  14. A compound statement or block consists of a statement or a group of statements surrounded by curly braces. The block is syntactically equivalent to a single statement and usually follows an if, else, while, or for construct. This is a block: { statement; statement; statement }   7.1.1. Conditionals Conditional constructs control the flow of a program. If a condition is true, the program will execute a block of statements and if the condition is false, flow will go to an alternate block of statements. Decision-making constructs (if, else, switch) contain a control expression that determines whether or not a block of expressions will be executed. If the condition after the if is met, the result is true, and the following block of statements is executed; otherwise, the result is false and the block is not executed. Format if (condition){ statements; }   Example: if ( $age > 21 ){ print "Let's Party!"; } The block of statements (or single statement) is enclosed in curly braces. Normally statements are executed sequentially. If there is only one statement after the conditional expression, the curly braces are optional. if/else “You better pay me now, or else . . .” Have you heard that kind of English statement before? PHP statements can be handled the same way with the if/else branching construct. This construct allows for a two-way decision. The if evaluates the first conditional expression in parentheses, and if the expression evaluates to true, the block after the opening curly braces is executed; otherwise, the block after the else is executed. The else is optional. See Example 7.1. Format if (condition){ statements1; } else{ statements2; }   Example: if ( $x > $y ){ print "$x is larger"; } else{ print "y is larger"; } Example 7.1. Code  View:        (The HTML Form) Your Fare How old are you? ------------------------------------------------------------------ (The PHP Script) Your Fare Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  15. Explanation 1 If  the  variable  has  not  been  set,  the  program  will  exit. 2– If  the  value  of  the  variable  $age  is  greater  than  or  equal  to  55,  lines  3  and  4  are   4 executed.  See  Figures  7.2  and  7.3. 5 This  closing  curly  brace  closes  the  block  of  statements  following  the  if  expression.   Because  there  is  only  one  statement  in  the  block,  the  curly  braces  are  not  required. 6– The  else  statements,  lines  7  and  8,  are  executed  if  the  expression  in  line  2  is  false. 8   Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  16. Figure 7.2. The HTML form from Example 7.1.   Figure 7.3. After the user presses the “Get Fare” button to submit the form. Output of the PHP script from Example 7.1.   if/elseif If you’ve got $1, we can go to the Dollar Store, else if you’ve got $10, we could get a couple of movies, else if you’ve got $20 we could buy a CD . . . or else forget it!” PHP provides yet another form of branching, the if/elseif construct. This construct provides a multiway decision structure. Format if (condition) { statements1; } elseif (condition) { statements2; } elseif (condition) { statements3; } else{ statements4; } If the first conditional expression following the if keyword is true, the statement or block of statements following the expression are executed and control starts after the else block. Otherwise, if the conditional expression following the if keyword is false, control branches to the first elseif and the expression following it is evaluated. If that expression is true, the statement or block of statements following it are executed, and if false, the next elseif is tested. All else ifs are tested and if none of their expressions are true, control goes to the else statement. Although the else is not required, it normally serves as a default action if all previous conditions were false. See Example 7.2 for if/elseif construct. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  17. Example 7.2. Code  View:   (The HTML Form) Your Movie Fare
  18. 10 ?> Explanation 1 The  HTML  form  starts  here.  The  action  attribute  is  assigned  the  name  of  the   PHP  script  that  will  be  executed  after  the  form  is  submitted. 2 The  text  box  is  named  "age"  and  will  be  sized  to  hold  three  characters. 3 The  HTML  submit  input  type  is  given  a  name,  submit_fare,  that  will  be  used  in   the  following  PHP  script. 4 The  opening  PHP  tag  tells  PHP  to  start  processing. 5 Now  we  are  looking  at  the  PHP  instructions.  If  the  user  pressed  the  submit   button,  this  file  will  execute.  PHP  will  store  the  names  of  the  input  devices  in   variables,  $age  and  $submit_fare.  This  conditional  expression  tests  to  see  if   those  variables  were  set.  If  they  weren’t  set,  then  the  form  was  either  not   submitted  or  the  user  left  it  empty,  or  both. 6 If  is  true  that  the  user’s  age  is  greater  than  0  and  also  less  than  13,  the  block   that  follows  the  expression  will  be  executed.  As  soon  as  the  block  is  executed,   the  program  will  start  execution  on  line  10.  If  the  expression  evaluates  to  false,   then  the  program  will  go  to  line  7. 7 If  the  condition  on  line  6  is  false,  the  program  checks  the  conditional   expression  after  the  elseif,  and  if  it  is  true  (i.e.,  the  age  is  greater  than  or   equal  to  13  and  less  than  55),  the  block  of  statements  will  be  executed.   Otherwise,  the  program  will  go  to  line  8. 8 If  the  conditional  test  in  line  7  is  false,  this  elseif  condition  will  be  checked,   and  if  true,  the  block  of  statements  following  it  will  be  executed.  If  false,  the   block  of  statements  after  the  else  on  line  9  are  executed. 9 If  none  of  the  preceding  conditions  are  met,  control  goes  to  the  else  block,   often  called  the  default  condition,  and  the  statements  in  its  block  are  executed. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  19. Figure 7.4. The HTML form from Example 7.2.   Figure 7.5. The PHP output from Example 7.2.       The switch Statement The switch statement is an alternative to the if/elseif conditional construct, commonly called a a case statement, and often makes the program more readable when handling multiple options. Format switch (expression){ case label : statement(s); break; case label : statement(s); break; ... default : statement; }   Example: switch ($color){ case "red": print "Hot!"; break; case "blue": print "Cold."; break; default: print "Not a good choice."; break; } The value of the switch expression is matched against the expressions, called labels, following the case keyword. The case labels are constants, either string or numeric. Each label is terminated with a colon. The default label is optional, but its action is taken if none of the other cases match the switch expression. After a match is found, the statements after the matched label are executed for that case. If none of the cases are matched, the control drops to the default case. The default is optional. If a break statement is omitted, all statements below the matched label are executed until either a break is reached or the entire switch block exits. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
  20. Example 7.3. Code  View:   (The HTML File) Pick a Font Color Choose a font color: red blue purple green ------------------------------------------------------------------ (The PHP Script) Font Color 1 3
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