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
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.
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 $search_array = array('first' => null, 'second' => 4); // returns false isset($search_array['first']); // returns true array_key_exists('first', $search_array); ?>
Notes
Note:
For backward compatibility reasons, array_key_exists() will also return
TRUE
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 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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Licensed under the Creative Commons Attribution License v3.0 or later.
https://secure.php.net/manual/en/function.array-key-exists.php