Question

Here is my code

<?php

function random_id() {
    $chars = 'abcdefghijklmnopqrstuvwxyz1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $id = '';
    for ($i = 0; $i < 5; ++$i)
    {
        $id .= $chars[rand(1, 26)];
    }
    echo $id;
}

random_id();

?>

It keeps generating IDs with 5 lowercase digits, and VERY occasionally it will have a number in it. I tried with mt_rand() as well, and also using srand(time()) and srand(microtime()) at the beginning of the script before the loop.

Also, should it be rand(1, 26) or rand(0, 25)?

Answer 1

Your string is longer than 26 characters. Use this rand function instead:

rand(0, strlen($chars) - 1)

So that you’re not calculating string length on every iteration, but still keeping it dynamic, it is worth considering moving the calculation outside of the loop like so:

$chars = 'abcdefghijklmnopqrstuvwxyz1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ';
$chars_cnt = strlen($chars) - 1;
for ($i = 0; $i < 5; ++$i)
{
    $id .= $chars[rand(1, $chars_cnt)];
}