(PHP 4 >= 4.1.0)

array_key_exists -- Checks if the given key or index exists in the array


bool array_key_exists ( mixed key, array search)

array_key_exists() returns TRUE if the given key is set in the array. key can be any value possible for an array index.

Example 1. array_key_exists() example

$search_array = array("first" => 1, "second" => 4);
if (array_key_exists("first", $search_array)) {
    echo "The 'first' element is in the array";

Note: The name of this function is key_exists() in PHP version 4.0.6.

See also isset().