protected function randomLetters()
    {
        for ($i = 0; $i < $this->length; $i++)
        {
            $letters     = $this->letters[mt_rand(0, count($this->letters) - 1)];
            $this->code .= $letters[mt_rand(0, strlen($letters) - 1)];
        }
    }
protected function randomLetters()
    {
        for ($i = 0; $i < $this->length; $i++)
        {
            $letters     = $this->letters[mt_rand(0, count($this->letters) - 1)];
            $this->code .= $letters[mt_rand(0, strlen($letters) - 1)];
        }
    }
protected function randomLetters ( ) { for ( $ i = 0 ; $ i < $ this -> length ; $ i ++ ) { $ letters = $ this -> letters [ mt_rand ( 0 , count ( $ this -> letters ) - 1 ) ] ; $ this -> code .= $ letters [ mt_rand ( 0 , strlen ( $ letters ) - 1 ) ] ; } }
Random generation English & Numbers letters

@return void
Random generation English & Numbers letters