多态的好处：

1.组织结构清晰

2.可读性强

3.对于前期和后期的维护性高

实现一个计算器的多态

1 #include
     
       2 using namespace std; 3 class abstractcaculator 4 { 5     public: 6         virtual int getresult() 7         { 8             return 0; 9         }10         int a;11         int b;12 };13 class add:public abstractcaculator14 {15     public:16         int getresult()17         {18             return a + b;19         }20 };21 class sub:public abstractcaculator22 {23     public:24         int getresult()25         {26             return a - b;27         }28 };29 class mul:public abstractcaculator30 {31     public:32         int getresult()33         {34             return a * b;35         }36 };37 38 void test()39 {40     abstractcaculator *abc = new add;41     abc->a = 10;42     abc->b = 10;43     cout << abc->a <<" + " << abc->b << " = " << abc->getresult() << endl;44     delete abc;45     46     abc = new sub;47     abc->a = 10;48     abc->b = 10;49     cout << abc->a <<" - " << abc->b << " = " << abc->getresult() << endl;50     delete abc;51     52     abc = new mul;53     abc->a = 10;54     abc->b = 10;55     cout << abc->a <<" * " << abc->b << " = " << abc->getresult() << endl;56     delete abc;57 }58 59 int main()60 {61     test();62     return 0;63 }