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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() returns TRUE if the
given key is set in the array.
key can be any value possible
for an array index.
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
TRUEifkeyis a property defined within an object given asarray. This behaviour should not be relied upon, and care should be taken to ensure thatarrayis 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
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