Checks if the given key or index exists in the array


(PHP 4 >= 4.0.7, PHP 5)

array_key_existsChecks 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.



Value to check.


An array with keys to check.

Return Values

Returns TRUE on success or FALSE on failure.


Example #1 array_key_exists() example

= array('first' => 1'second' => 4);
if (
array_key_exists('first'$search_array)) {
"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.

= array('first' => null'second' => 4);

// returns false

// returns true



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


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

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

See Also

  • isset() - Determine if a variable is set and is not 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

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