Fast and simple getRandNumber function (PHP)

getRandNumber.php

<?php

$num = getRandNumber(5);

var_dump($num); // 5-digits number like 48149

/**
 * Returns fixed-length random integer.
 */
function getRandNumber(int $length): int
{
    if($length > 19) {
        throw new \RuntimeException('Maximum value for a 64-bit signed integer was overheaded');
    }
    
    $min = '1' . str_repeat('0', $length-1);
    $max = str_repeat('9', $length);
    
    return rand((int) $min, (int) $max);
}