PHP Manual: Fetch a key from an array

Description

intstringnull key(arrayobject $array)

key returns the index element of the current array position.

Parameters

array: The array.

Return Values

The key function simply returns the key of the array element that's currently being pointed to by the internal pointer. It does not move the pointer in any way. If the internal pointer points beyond the end of the elements list or the array is empty, key returns null.

Changelog

Version	Description
8.1.0	Calling this function on objects is deprecated. Either convert the object to an array using get_mangled_object_vars first, or use the methods provided by a class that implements Iterator, such as ArrayIterator, instead.
7.4.0	Instances of SPL classes are now treated like empty objects that have no properties instead of calling the Iterator method with the same name as this function.

Examples

Example #1 key example

<?php
$array = array(
    'fruit1' => 'apple',
    'fruit2' => 'orange',
    'fruit3' => 'grape',
    'fruit4' => 'apple',
    'fruit5' => 'apple');

// this cycle echoes all associative array
// key where value equals "apple"
while ($fruit_name = current($array)) {
    if ($fruit_name == 'apple') {
        echo key($array), "\n";
    }
    next($array);
}
?>

The above example will output:

fruit1
fruit4
fruit5

key

Description

Parameters

Return Values

Changelog

Examples

See Also