Convert assoc values from alpha to numeric position of the alhapbet

gistfile1.aw

<?php
$array = array('hi' => 'a', 'yo' => 'b');
array_walk($array, function(&$value, $key){
    $value = strpos('abcdefghijklmnopqrstuvwxyz', $value) + 1;
});
print_r($array); // Array ( [hi] => 1 [yo] => 2 )


// < PHP 5.3
function alphanum(&$value, $key){
    $value = strpos('abcdefghijklmnopqrstuvwxyz', $value) + 1;
}
$array = array('hi' => 'a', 'yo' => 'b');
array_walk($array, 'alphanum');
print_r($array); // Array ( [hi] => 1 [yo] => 2 )