(PHP 4, PHP 5, PHP 7)

keyFetch a key from an array


key ( array $array ) : mixed

key() returns the index element of the current array position.



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.


Version Description
7.0.0 array is now always passed by value. Prior to this version, it was passed by reference if possible, and by value otherwise.


Example #1 key() example

= 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 (
$fruit_name == 'apple') {
key($array).'<br />';

The above example will output:

fruit1<br />
fruit4<br />
fruit5<br />

See Also

  • current() - Return the current element in an array
  • next() - Advance the internal pointer of an array
  • foreach

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