array_keys

array array_keys(array array) 

Returns all valid keys for the given array.

Returns:

Indexed array of keys; NULL on failure

Description:

Retrieves all the keys from an array and returns them as an indexed array.

Version:

PHP 4

Existing since version 4.0

Example:

Get the keys from arrays

$hash1 = array("lions", "tigers", "bears", "oh my"); 
$hash2 = array("r" => "red", "g" => "green", "b" => "blue"); 
echo "Keys for \$hash1: ", implode(", ", array_keys($hash1)), "\n"; 
echo "Keys for \$hash2: ", implode(", ", array_keys($hash2)); 

Output: 
Keys for $hash1: 0, 1, 2, 3 
Keys for $hash2: r, g, b