Simple function to generate random string (number & capital number) in php

simple_random_string.php

<?php

// turn on strict type mode.
declare (strict_type = 1);

/**
 * build your own random string.
 */
function make_rand(int $key_length = 0, string $new_space = null): string
{
    if (!$key_length) {
        return (string) null;
    }

    $key_space = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    if ($new_space) {
        /**
         * if $new_space available, concat to base $key_space &
         * validate $new_space must be letters and numbers.
         */
        $key_space .= preg_replace('/[^A-Za-z0-9\-]/', rand(0, 9), $new_space);
    }

    $rand_string = '';

    for ($i = 0; $i < $key_length; $i++) {
        $pos = rand(0, strlen($key_space) - 1);

        $rand_string .= $key_space[$pos];
    }

    // change the output to uppercase.
    return (string) strtoupper($rand_string);
}

// make random string and a length is 10.
echo make_rand(10);

Fire