Bob Jenkins' One-At-A-Time hashing algorithm.

jenkins_one_at_a_time_hash.php

<?php

// Bob Jenkins' One-At-A-Time hashing algorithm.
function jenkins_hash($key) {
    $key = (string)$key;
    $len = strlen($key);
    for($hash = $i = 0; $i < $len; ++$i) {
        $hash += ord($key[$i]);
        $hash += ($hash << 10);
        $hash ^= ($hash >> 6);
    }
    $hash += ($hash << 3);
    $hash ^= ($hash >> 11);
    $hash += ($hash << 15);
    return str_pad(dechex($hash),16,0,STR_PAD_LEFT);
}

This COPY-PAST C/C++ implementation is wrong for PHP.
Please check sample tests from Wikipedia:
https://en.wikipedia.org/wiki/Jenkins_hash_function

TESTS:

C / C++:
one_at_a_time("The quick brown fox jumps over the lazy dog", 43)
0x519e91f5 - CORRECT!

PHP (code above):
jenkins_hash("The quick brown fox jumps over the lazy dog")
0x31c25ec1 - INCORRECT!