key
    (PHP 3, PHP 4 , PHP 5)
key -- Fetch a key from an associative array
Description
mixed 
key ( array &array)
     key() returns the index element of the
     current array position.
    
     
Example 1. key() example 
<?php $array = array(     'fruit1' => 'apple',     'fruit2' => 'orange',     'fruit3' => 'grape',     'fruit4' => 'apple',     'fruit5' => 'apple');
  // this cycle echoes all associative array // key where value equals "apple" while ($fruit_name = current($array)) {     if ($fruit_name == 'apple') {         echo key($array).'<br />';     }     next($array); } ?>
 |  
  | 
    
     See also current() and next().