in_array
    (PHP 4 )
in_array -- Return 
TRUE if a value exists in an array
Description
bool 
in_array ( mixed needle, array haystack [, bool strict])
     Searches haystack for
     needle and returns TRUE
     if it is found in the array, FALSE otherwise.
    
     If the third parameter strict is set to
     TRUE then the in_array() function
     will also check the types of
     the needle in the haystack.
    
Note: 
      If needle is a string, the comparison is done in
      a case-sensitive manner.
     
Note: 
      In PHP versions before 4.2.0 needle was not
      allowed to be an array.
     
     
| Example 1. in_array() example | $os = array ("Mac", "NT", "Irix", "Linux");
if (in_array ("Irix", $os)) {
    print "Got Irix";
}
if (in_array ("mac", $os)) {
    print "Got mac";
} | 
 
       The second condition fails because in_array()
       is case-sensitive, so the program above will display:
        | 
    
     
| Example 2. in_array() with strict example | <?php
$a = array('1.10', 12.4, 1.13);
if (in_array('12.4', $a, TRUE))
    echo "'12.4' found with strict check\n";
if (in_array(1.13, $a, TRUE))
    echo "1.13 found with strict check\n";
?> | 
 
       This will display:
        | 1.13 found with strict check | 
 | 
    
     
| Example 3. in_array() with an array as needle | <?php
$a = array(array('p', 'h'), array('p', 'r'), 'o');
if (in_array(array ('p', 'h'), $a))
    echo "'ph' was found\n";
if (in_array(array ('f', 'i'), $a))
    echo "'fi' was found\n";
if (in_array('o', $a))
    echo "'o' was found\n";
?>
// This will output:
'ph' was found
'o' was found | 
 | 
    
     See also array_search().