高八位和低八位运算方法，两种计算方法

            quint16 x,y,z,x2,x3,x4;
            y=9;
            z=65414;
            x = (quint16)((y*256)&0xFF00)+(quint16)(z&0x00FF);
            qDebug()<<"x："<<x;//2438
            //方法1：
            x2 = (quint16)((y*256))+(quint16)(z%256);
            qDebug()<<"x2："<<x2;//2438
            //方法2：低八位需要做限制
            x3 = (quint16)((y*256))+(quint16)(z&0x00FF);
            qDebug()<<"x3:"<<x3;//2438