PHP 8 reference · Array Functions

PHP array_flip() Function

Swap keys and values, so each value becomes a key. Values must be strings or integers; duplicates keep the last key.

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Syntax

array_flip(array $array): array

Parameter	Description
`array`	The input array.

The flipped array.

Swap keys and valuesTry it yourself

<?php
print_r(array_flip(["a" => 1, "b" => 2]));

Output

Array
(
    [1] => a
    [2] => b
)

Fast lookups with isset()Try it yourself

<?php
$allowed = array_flip(["jpg", "png", "gif"]);
var_dump(isset($allowed["png"]), isset($allowed["exe"]));

Output

bool(true)
bool(false)

Version	Change
PHP 4.0	Added

array_keys() · Return all the keys of an array, or only the keys whose value matches a search value.
array_combine() · Create an array by using one array for keys and another for values. Both arrays must have the same number of elements.
in_array() · Check whether a value exists in an array. Pass true as the third argument for a strict (===) comparison.
PHP Arrays · tutorial
PHP Array Functions · tutorial