PHP array_flip: Swapping Array Keys and Values

The array_flip() function returns a new array where the original array's keys become values and its values become keys.

Values in the input array must be valid keys (integers or strings); otherwise a warning is issued and those pairs are omitted.

If a value appears multiple times, the last corresponding key is kept and earlier ones are discarded.

Parameter: trans – the array whose keys and values you want to exchange.

Return value: The flipped array on success, or NULL on failure.

Example 1:

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

Output:

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

Example 2 (demonstrating duplicate handling):

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

Output:

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