明一个Cat类，拥有静态数据成员HowManyCats，记录Cat的个体数目；声明静态成员函数GetHoMany(),存取HowManyCats。设计程序测试这个类，体会静态数据成员和静态成员函数的用法。-States members GetHoMany () function, access HowManyCats design program test this class, experience static data members and static member functions usage please will complete program, and give the execution of the program results