array_key_exists

(PHP 4 >= 4.0.7, PHP 5)

array_key_exists — Checks if the given key or index exists in the array

Description

bool array_key_exists ( mixed $key , array $search )

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.

search

An array with keys to check.

Return Values

Returns TRUE on success or FALSE on failure.

ChangeLog

Version Description
5.3.0 This function doesn't work with objetcs anymore, property_exists() should be used in this case.

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";
}
?>

Note: The name of this function is key_exists() in PHP 4.0.6.

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);
?>

See Also

     

 

 
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