求3个长方体的体积，编写的一个基于对象的程序。数据成员包括长，宽，高。并用成员函数实现其功能，计算出3个长方体的体积。-3 cuboid find the volume of an object-based writing program. Data members, including length, width and height. And their function with the member function to calculate the three rectangular volume.