来自php和javascript的相同功能的两个不同输出

Question

I have a function djb2 on php and javascript, php

function hash_djb2($str){
$hash = 5381;
$length = strlen($str);
for($i = 0; $i < $length; $i++) {
    $hash = (($hash << 5) + $hash) + $str[$i];
}
return $hash;
}

and javascript

djb2Code = function(str){
var hash = 5381;
for (i = 0; i < str.length; i++) {
    char = str.charCodeAt(i);
    hash = ((hash << 5) + hash) + char; /* hash * 33 + c */
}
return hash;
}

on php I call

hash_djb2("123456789egrdhfdtjdtjdtjrt");

and the output is

-4235984878

and in javascript I call

djb2Code("123456789egrdhfdtjdtjdtjrt");

and the output is

27338942

Why is that and how can I fix it?

Thank you

Answer 1

Those are not the same functions. Your PHP uses $str[$i], which is a character. Your JavaScript function uses char.charCodeAt(i) which returns integer.

Change your PHP function like this ...

function hash_djb2($str){
    $hash = 5381;
    $length = strlen($str);
    for($i = 0; $i < $length; $i++) {
        $char = ord($str[$i]);                     // this line is added
        $hash = (($hash << 5) + $hash) + $char;    // this line is modified
    }
    return $hash;
}