array_flip

Syntax:array array_flip ( array $trans ) Description:Exchanges all keys with their associated values in an array
<?php
$trans = array("a" => 1, "b" => 1, "c" => 2);
$trans = array_flip($trans);
print_r($trans);
?>
OUTPUT

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