php man page for array_keys

ARRAY_KEYS(3)								 1							     ARRAY_KEYS(3)

array_keys - Return all the keys or a subset of the keys of an array

SYNOPSIS
       array array_keys (array	$array, [mixed	$search_value], [bool  $strict = false])

DESCRIPTION
       array_keys(3) returns the keys, numeric and string, from the $array.

	If  the  optional  $search_value is specified, then only the keys for that value are returned. Otherwise, all the keys from the $array are
       returned.

PARAMETERS
	      o $array
		- An array containing keys to return.

	      o $search_value
		- If specified, then only keys containing these values are returned.

	      o $strict
		- Determines if strict comparison (===) should be used during the search.

RETURN VALUES
	Returns an array of all the keys in $array.

EXAMPLES
       Example #1

	      array_keys(3) example

	      <?php
	      $array = array(0 => 100, "color" => "red");
	      print_r(array_keys($array));

	      $array = array("blue", "red", "green", "blue", "blue");
	      print_r(array_keys($array, "blue"));

	      $array = array("color" => array("blue", "red", "green"),
			     "size"  => array("small", "medium", "large"));
	      print_r(array_keys($array));
	      ?>

	      The above example will output:

	      Array
	      (
		  [0] => 0
		  [1] => color
	      )
	      Array
	      (
		  [0] => 0
		  [1] => 3
		  [2] => 4
	      )
	      Array
	      (
		  [0] => color
		  [1] => size
	      )

SEE ALSO
       array_values(3), array_key_exists(3), array_search(3).

PHP Documentation Group 													     ARRAY_KEYS(3)