Php/docs/function.array-key-exists
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
( string|int $key
, array $array
) : bool
array_key_exists() returns TRUE
if the
given key
is set in the array.
key
can be any value possible
for an array index.
Parameters
key
- Value to check.
array
- An array with keys to check.
Return Values
Returns TRUE
on success or FALSE
on failure.
Note:
array_key_exists() will search for the keys in the first dimension only. Nested keys in multidimensional arrays will not be found.
Examples
Example #1 array_key_exists() example
<?php$search_array = array('first' => 1, 'second' => 4);if (array_key_exists('first', $search_array)) { echo "The 'first' element is in the array";}?>
Example #2 array_key_exists() vs isset()
isset() does not return TRUE
for array keys
that correspond to a NULL
value, while
array_key_exists() does.
<?php$search_array = array('first' => null, 'second' => 4);// returns falseisset($search_array['first']);// returns truearray_key_exists('first', $search_array);?>
Notes
Note:
For backward compatibility reasons, array_key_exists() will also return
TRUE
ifkey
is a property defined within an object given asarray
. This behaviour should not be relied upon, and care should be taken to ensure thatarray
is an array.To check whether a property exists in an object, use property_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