public function increment($delt = 1)
    {
        $n = $this->get();
        $n += $delt;
        $this->set($n);
        return $n;
    }
public function increment($delt = 1)
    {
        $n = $this->get();
        $n += $delt;
        $this->set($n);
        return $n;
    }
public function increment ( $ delt = 1 ) { $ n = $ this -> get ( ) ; $ n += $ delt ; $ this -> set ( $ n ) ; return $ n ; }
if you want't to log the number under multi-thread system,
please open the lock, use a+ mod. then fopen the file will not
destroy the data.

this function increment a delt value , and save to the file.

@param int $delt
@return int
if you want t to log the number under multi - thread system please open the lock use a + mod . then fopen the file will not destroy the data .