public function readBytes($num)
    {
        $returnValue = substr($this->_data, $this->_position, $num);
        $this->_position += $num;

        return $returnValue;
    }
public function readBytes($num)
    {
        $returnValue = substr($this->_data, $this->_position, $num);
        $this->_position += $num;

        return $returnValue;
    }
public function readBytes ( $ num ) { $ returnValue = substr ( $ this -> _data , $ this -> _position , $ num ) ; $ this -> _position += $ num ; return $ returnValue ; }
Read num bytes from the current position in the file
and advances the file pointer.

@param  integer $num
@return string
Read num bytes from the current position in the file and advances the file pointer .