ARRAY_KEY_EXISTS(3) 1 ARRAY_KEY_EXISTS(3)
array_key_exists - Checks if the given key or index exists in the array
SYNOPSIS
bool array_key_exists (mixed $key, array $array)
DESCRIPTION
array_key_exists(3) returns TRUE if the given $key is set in the array. $key can be any value possible for an array index.
PARAMETERS
o $key
- Value to check.
o $array
- An array with keys to check.
RETURN VALUES
Returns TRUE on success or FALSE on failure.
EXAMPLES
Example #1
array_key_exists(3) 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(3) vs isset(3)
isset(3) does not return TRUE for array keys that correspond to a NULL value, while array_key_exists(3) 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(3)
Note
For backward compatibility reasons, array_key_exists(3) 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(3).
SEE ALSO
isset(3), array_keys(3), in_array(3), property_exists(3).
PHP Documentation Group ARRAY_KEY_EXISTS(3)
