(PHP 4 >= 4.0.7, PHP 5, PHP 7)
Checks if the given key or index exists in the array
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.
Returns:
Returns TRUE
on success or FALSE
on failure.
Notes:
For backward compatibility reasons, array_key_exists() 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().
Examples:
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"; } ?>
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); ?>
See also:
isset() -
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