php man page for key

KEY(3)									 1								    KEY(3)

key - Fetch a key from an array

SYNOPSIS
       mixed key (array  &$array)

DESCRIPTION
       key(3) returns the index element of the current array position.

PARAMETERS
	      o $array
		- The array.

RETURN VALUES
	The  key(3)  function  simply  returns the key of the array element that's currently being pointed to by the internal pointer. It does not
       move the pointer in any way. If the internal pointer points beyond the end of the elements list or the array is empty, key(3) returns NULL.

EXAMPLES
       Example #1

	      key(3) 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);
	      }
	      ?>

	      The above example will output:

	      fruit1<br />
	      fruit4<br />
	      fruit5<br />

SEE ALSO
       current(3), next(3).

PHP Documentation Group 														    KEY(3)