左移运算符 优先级很低

写了一个大小端转换的代码

int x =recv(sockConn, (char*)buf, len, 0);
			cout << "data read:" << x << endl;
			for(int i = 0; i < 30; i++)
				cout << hex << (int)buf[i] << endl;
			frameInfo info;

			//info.resolutionWidth = buf[0] << 8 +buf[1];

//之前每个语句都如上面这句，结果不对，info.resolutionWidth = (buf[0] << 8) +buf[1];info.resolutionHeight = (buf[2] << 8) + buf[3];info.x = (buf[4] << 8) + buf[5];info.y =(buf[6] << 8) + buf[7];info.w = (buf[8] << 8) + buf[9];info.h = (buf[10] << 8) + buf[11];cout <<dec<< info.resolutionHeight << endl;cout << info.resolutionWidth << endl;cout << info.w << endl;

运行结果怎么都不是期望的方式，后来发现，左移运算符优先级低于加号运算符，加括号解决问题