array_keys

Description

array_keys() returns the keys, numeric and string, from the input array.

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

Example 1. array_keys() 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 printout of the program above will be: Array ( [0] => 0 [1] => color ) Array ( [0] => 0 [1] => 3 [2] => 4 ) Array ( [0] => color [1] => size )

See also array_values() and array_key_exists().