Question

I am creating a function that I would like to generate random strings from a given set of characters. I would like to allow users to specify a regex character class instead of requiring them to specify every single character.
For example:

function a($length, $allowed_chars){
    for ($i = 0, $salt = ""; $i < $length; $i++){
        $salt .= __GET_ONE_RANDOM_CHAR_FROM_ALLOWED_CHARS__;
    }
}

If allowed chars is a string of all allowed characters, then this is simple:

$characterList{mt_rand(0,strlen($characterList)-1)};

I would like to be able to specify allowed chars like this "./0-9A-Za-z" instead of "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"

Answer 1

I didint check but, i think you will understand main idea

function a($length, $allowed_chars){

    $allowedCharsList = join('', array_merge(range(chr(0x1f), chr(0x23)), range(chr(0x25), chr(0x80)) )); //all printable (ascii) characters except '$'
    $allowed_chars = preg_replace("/[^$allowed_chars]/", '', $allowedCharsList);
    for ($i = 0, $salt = ""; $i < $length; $i++){
        $salt .= $allowed_chars{mt_rand(0,strlen($allowed_chars)-1)};
    }

    return $salt;
}


echo a(10, '0-9h-w');