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== PHP tags: ==
== PHP tags: ==
 
{{ntnes}}
=== '''<?php [code] ?>''' ===
=== '''<?php [code] ?>''' ===


* Enclose php code
* Enclose php code


* Can be configured in the php.ini to be <? ?>, <script language="php"> </script> etc.
* Can be configured in the <code>php.ini</code> to be <code><? ?></code>, <code><script language="php"> </script></code> etc.


* Embedded in normal HTML code
* Embedded in normal HTML code
Line 13: Line 13:
Example:  
Example:  


<source lang="php">
  <?php
  <?php
  print “Hello World\n”;
  print "Hello World\n";
  $date = date(“Y-m-d H:i:s”);
  $date = date("Y-m-d H:i:s");
  print “The date and time at the moment is $date”;
  print "The date and time at the moment is $date";
  ?>
  ?>
</source>


=== '''<?=''' ===
=== '''<?=''' ===
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Example:   
Example:   
<source lang="php">
  <?php
  <?php
  $name = "Bobby";
  $name = "Bobby";
Line 30: Line 34:
   
   
  <?=$name?>
  <?=$name?>
</source>
Which will output ''Bobby''.
Which will output ''Bobby''.


Example:
Example:
  <?=date(“Y-m-d H:i:s”)?>  
 
<source lang="php">
  <?=date("Y-m-d H:i:s")?>
</source>


Which will output something like ''2005-11-09 19:40:05''.
Which will output something like ''2005-11-09 19:40:05''.
[[]]


== Commenting ==
== Commenting ==
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* Example:
* Example:
  echo “Hello”; # Everything from the hash is commented out
<source lang="php">
  echo "Hello"; # Everything from the hash is commented out
</source>


* Example:
* Example:
<source lang="php">
  # This entire line is commented out
  # This entire line is commented out
</source>


==='''//'''===
==='''//'''===
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* Example:  
* Example:  
<source lang="php">
  /*All of this is
  /*All of this is
  commented out.
  commented out.
  Even this line!*/
  Even this line!*/
</source>


== Variables ==
== Variables ==
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➢ Variables in PHP are denoted by the $ prefix.
➢ Variables in PHP are denoted by the $ prefix.


e.g. : $a = “Hello World”; # this assigns the string “Hello World” to $a.
* Example:
 
<source lang="php">
e.g. : $b = “$a, I'm Ralfe”; # this assigns “Hello World, I'm Ralfe” to $b.
$a = “Hello World”; # this assigns the string “Hello World” to $a.
 
$b = “$a, I'm Ralfe”; # this assigns “Hello World, I'm Ralfe” to $b.
e.g. : $b = $a.”, I'm Ralfe”; # exactly the same as the previous example.
$b = $a.”, I'm Ralfe”; # exactly the same as the previous example.
 
</source>


➢ PHP supports dynamic variables.
➢ PHP supports dynamic variables.


e.g. : $c = “response”;
* Example:
<source lang="php">
$c = “response”;


e.g. : $$c = “Hello Ralfe”; # this assigns “Hello Ralfe” to $response.
$$c = “Hello Ralfe”; # this assigns “Hello Ralfe” to $response.
</source>




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definition. PHP handles all data type conversions.
definition. PHP handles all data type conversions.


e.g. : $a = 4;
* Example:
<source lang="php">
$a = 4;


e.g. : $b = 12;
$b = 12;


e.g. : print “The value of a is $a.”; # Uses a as a String.
print “The value of a is $a.”; # Uses a as a String.
 
e.g. : $c = $a + $b; # $a is now used as an Integer again.


$c = $a + $b; # $a is now used as an Integer again.
</source>


➢ PHP supports boolean variables, which can be assigned either a one or a zero, or a
➢ PHP supports boolean variables, which can be assigned either a one or a zero, or a
true or false.
true or false.


e.g. : $a = true;
Example:
<source lang="php">
$a = true;


e.g. : $b = 1;
$b = 1; # $a and $b are the same thing!


e.g. : # $a and $b are the same thing!
$c = false;


e.g. : $c = false;
$d = 0; # $c and $d are the same thing!
 
</source>
e.g. : $d = 0;
 
e.g. : # $c and $d are the same thing!


== Operators ==
== Operators ==
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➢ Arithmetic Operators
➢ Arithmetic Operators


* Example:
<source lang="php">
$a = 4;
$a = 4;


$b = 2;
$b = 2;


// Addition: $a + $b = 6
$a + $b = 6;  // Addition


// Subtraction: $a - $b = 2
$a - $b = 2;  // Subtraction


// Multiplication: $a * $b = 8
$a * $b = 8;  // Multiplication


// Division: $a / $b = 2
$a / $b = 2;  // Division


// Modulus: $a % $b = 0
$a % $b = 0;  // Modulus


// Increment: $a++
$a++;  // Increment


// Decrement: $a--
$a--;  // Decrement
</source>




➢ Assignment Operators
➢ Assignment Operators


* Example:
<source lang="php">
$a = 4;
$a = 4;


Line 139: Line 164:


// $b = 4;
// $b = 4;
 
</source>


➢ Comparison Operators
➢ Comparison Operators


* Example:
<source lang="php">
$a == $b // test if two values are equal
$a == $b // test if two values are equal


Line 154: Line 181:


$a >= $b // test if the first value is greater than or equal to the second
$a >= $b // test if the first value is greater than or equal to the second
</source>


== Concatenation ==
== Concatenation ==


* Example:
<source lang="php">
$a = "Fill the halls ";


$a = “Fill the halls “;
$b = "with poisoned ivy...";


$b = “with poisoned ivy...“;
$c = $a . $b;  # the '.' operator concatenates two variables.


$c = $a . $b; # the '.' operator concatenates two variables.
// $c = "Fill the halls with poisoned ivy...";
 
</source>
// $c = “Fill the halls with poisoned ivy...”


== Arrays ==
== Arrays ==
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PHP supports both numerically indexed arrays as well as associative arrays.
PHP supports both numerically indexed arrays as well as associative arrays.


* Example:
<source lang="php">
$a = array(1, 2, 3, 4);
$a = array(1, 2, 3, 4);


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// $a[3] = 4;
// $a[3] = 4;


$b = array(“name” => ”Fred”, “age” => 30);
$b = array("name" => "Fred", "age" => 30);


// $b['name'] = “Fred”;
// $b['name'] = "Fred";


// $b['age'] = 30;
// $b['age'] = 30;
</source>


== Decision and Loop Statements ==
== Decision and Loop Statements ==
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'''IF THEN ELSE statement'''
'''IF THEN ELSE statement'''


* Example:
<source lang="php">
  $a = 1;
  $a = 1;
  $b = 10;
  $b = 10;
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  // OUTPUT:
  // OUTPUT:
  // a is not greater than b
  // a is not greater than b
</source>


'''SWITCH statement'''
'''SWITCH statement'''


* Example:
<source lang="php">
  $a = 100;
  $a = 100;
   
   
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  // OUTPUT:
  // OUTPUT:
  // The value is 100
  // The value is 100
 
</source>


'''FOR statement'''
'''FOR statement'''


* Example:
<source lang="php">
  for ($i = 0; $i < 10; $i++) {
  for ($i = 0; $i < 10; $i++) {
     # initialize $i ; while condition ; increment statement
     # initialize $i ; while condition ; increment statement
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  // OUTPUT:
  // OUTPUT:
  // 0123456789
  // 0123456789
 
</source>


'''FOREACH statement'''
'''FOREACH statement'''


* Example:
<source lang="php">
  $a = array(1, 2, 3, 4, 5);
  $a = array(1, 2, 3, 4, 5);
   
   
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  // OUTPUT:
  // OUTPUT:
  // 12345
  // 12345
 
</source>


'''WHILE statement'''
'''WHILE statement'''


* Example:
<source lang="php">
  while ($row = mysql_fetch_row($result)){
  while ($row = mysql_fetch_row($result)){
     print $row[0];
     print $row[0];
  }
  }
 
</source>


'''DO WHILE statement'''
'''DO WHILE statement'''


* Example:
<source lang="php">
  $i = 0;
  $i = 0;
  # Note that it might seem that $i will
  # Note that it might seem that $i will
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  } while ($i >0);
  } while ($i >0);
  # least once!
  # least once!
</source>


== Functions ==
== Functions ==


* Example:
<source lang="php">
  function square_number($number) {
  function square_number($number) {
     return ($number * $number);
     return ($number * $number);
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  // OUTPUT:
  // OUTPUT:
  // The answer is 100
  // The answer is 100
</source>


== Classes ==
== Classes ==


* Example:
<source lang="php">
  class dog {
  class dog {
     var $name;
     var $name;
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     function who_am_i() {
     function who_am_i() {
       echo "My name is {$this->name), and I am a dog";
       echo "My name is {$this->name}, and I am a dog";
     }
     }
  }
  }
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  // OUTPUT:
  // OUTPUT:
  // My name is John, and I am a dog
  // My name is John, and I am a dog
</source>


[[../Introduction to PHP/|Previous: Introduction to PHP]] | [[../|TOC]] | [[../File Handling/|Next: File Handling]]
[[../Introduction to PHP/|Previous: Introduction to PHP]] | [[../|TOC]] | [[../File Handling/|Next: File Handling]]


[[Category:PHP]]
[[Category:PHP and MySQL Programming|{{SUBPAGENAME}}]]
[[Category:MySQL]]
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