array_flip

(PHP 4, PHP 5, PHP 7)

Exchanges all keys with their associated values in an array

array array_flip ( array $array )

array_flip() returns an array in flip order, i.e. keys from array become values and values from array become keys.

Note that the values of array need to be valid keys, i.e. they need to be either integer or string. A warning will be emitted if a value has the wrong type, and the key/value pair in question will not be included in the result.

If a value has several occurrences, the latest key will be used as its value, and all others will be lost.

Parameters:

array

An array of key/value pairs to be flipped.

Returns:

Returns the flipped array on success and NULL on failure.

Examples:

array_flip() example

<?php
$input = array("oranges", "apples", "pears");
$flipped = array_flip($input);

print_r($flipped);
?>

The above example will output:

Array
(
    [oranges] => 0
    [apples] => 1
    [pears] => 2
)

array_flip() example : collision

<?php
$input = array("a" => 1, "b" => 1, "c" => 2);
$flipped = array_flip($input);

print_r($flipped);
?>

The above example will output:

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