array_flip
Swaps keys and values.
Syntax
array_flip(array $array): arrayParameters
| Parameter | Type | Description |
|---|---|---|
| $array | array | The source array. |
Return value
arrayAn array in which the values became the keys.
Examples
Swapping keys and values:
<?php
echo json_encode(array_flip(['a' => 1, 'b' => 2]));Output:
{"1":"a","2":"b"}A fast membership check:
<?php
$allowed = array_flip(['jpg', 'png', 'webp']);
var_dump(isset($allowed['png']));
var_dump(isset($allowed['exe']));Output:
bool(true)
bool(false)Notes
The values must be strings or numbers. With repeated values the last key wins.
See also
- array_combine — Creates an array from two lists: keys and values.
- array_search — Searches an array for a value and returns its key.
In the tutorial
- Array functions — Processing arrays in PHP without loops — array_map, array_filter, array_reduce, searching and slicing.