Checks if the given key or index exists in the array (original) (raw)

array_key_exists

(PHP 4 >= 4.0.7, PHP 5, PHP 7)

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

Description

array_key_exists ( mixed $key , array $array ) : bool

Parameters

key

Value to check.

array

An array with keys to check.

Return Values

Returns TRUE on success or FALSE on failure.

Note:

array_key_exists() will search for the keys in the first dimension only. Nested keys in multidimensional arrays will not be found.

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, whilearray_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 reasons, array_key_exists() will also return TRUE if key is a property defined within an object given asarray. 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, useproperty_exists().

See Also

• isset() - Determine if a variable is declared and is different than NULL
• array_keys() - Return all the keys or a subset of the keys of an array
• in_array() - Checks if a value exists in an array
• property_exists() - Checks if the object or class has a property