Question

I am using this to generate a random number 0-3 and it works fine except every now and then it will return null and I’m not sure why. Any ideas would be great

function genRandomString($length=1,$characters = '0123',$string = '') {
for ($p = 0; $p < $length; $p++) {
    $string .= $characters[mt_rand(0, strlen($characters))];
}

return $string; } 

Answer 1

StrLen($characters) returns 4
mt_rand(0,4) will result in Random numbers ranging from 0 to inclusive 4.

$characters has a length of 4, sou you can access it from $characters[0] to $characters[3].
If you generate a random 4, you access $characters[4], and so you get your null