PHP Manual: Checks if the given key or index exists in the array

Description

bool array_key_exists ( mixed $key , array $array )

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

Parameters

key: Value to check.
array: An array with keys to check.

Return Values

Returns TRUE on success or FALSE on failure.

Examples

Example #1 array_key_exists example


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

Example #2 array_key_exists vs isset

isset does not return TRUE for array keys that correspond to a NULL value, while array_key_exists does.


<?php
$search_array = array('first' => null, 'second' => 4);

// returns false
isset($search_array['first']);

// returns true
array_key_exists('first', $search_array);
?>

Notes

Note:
For backward compatibility, the following deprecated alias may be used: key_exists

Note:
For backward compatibility reasons, array_key_exists will also return TRUE if key is a property defined within an object given as array. This behaviour should not be relied upon, and care should be taken to ensure that array is an array.

To check whether a property exists in an object, use property_exists.

array_key_exists

Description

Parameters

Return Values

Examples

Notes

See Also