Password Generator (/r/dailyprogrammer)

function generate_password($length = 20)
{
    $characters = str_split('abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789');
    $password = '';

    for($i = 0; $i < $length; ++$i)
    {
        $password .= $characters[array_rand($characters)];
    }
    return $password;
}