Random String Generator

The following generates a pseudo random string using the PHP function mt_rand(int $min, int $max): int. The resulting string contains upper and lower case letters (a-z og A-Z) and intergers (0-9) in a statistical 50-50 mix of letters and numbers. Use for generating e.g. temporary passwords or tokens. Input desired output length and click!

Though for cryptographic purposes one should rather use the function random_bytes(int $length): string.

Generate Random String

Source Code

random_string.php

<?php
    // Print a pseudo random string 20 characters long:
    echo getRandomStr(20);

    /**
     * Creates a pseudo random string of the specified length from the
     * characters a-z, A-Z (50%), and 0-9 (50%).
     * @param $length int    The length of the string to be created.
     * @return String        The random string created.
     */
    function getRandomStr(int $length = 20): string
    {
        $randomStr = "";
        
        for ($i = 0; $i < $length; $i++) {
            $n = mt_rand(1,4);
            
            if ($n == 1) {
                $randomStr .= chr(mt_rand(65,90));    // ASCII-values capital letters
            }
            elseif ($n == 2) {
                $randomStr .= chr(mt_rand(97,122));    // ASCII-values small letters
            }
            else {
                $randomStr .= chr(mt_rand(48,57));    // ASCII-values numbers
            }
        }
        
        return $randomStr;
    }
?>