C++学习基础九——继承

 1 #include <iostream>
 2 #include <string>
 3 
 4 using namespace std;
 5 
 6 class Item_base
 7 {
 8 public:
 9     Item_base(const string &is,double p):isbn(is),price(p){}
10     string book()
11     {
12         return isbn;
13     }
14     virtual double calMoney(int c)
15     {
16         return c * price;
17     }
18 private:
19     string isbn;
20 protected:
21     double price;    
22 };
23 
24 class Bulk_item : public Item_base
25 {
26 public:
27     Bulk_item::Bulk_item(const string &is,double p,int c,double dis):
28         Item_base(is,p),min_py(c),discocunt(dis){}
29     double calMoney(int c)
30     {
31         cout<<endl<<"子类"<<endl; 
32         if(c > min_py)
33         {
34             return c * price * discocunt;
35         }
36         else
37         {
38             return c * price;
39         }
40     } 
41     void test()
42     {
43         cout<<endl<<"子类测试！！"<<endl;
44     }
45 private:
46     int min_py;
47     double discocunt;
48 };
49 
50 
51     
52 int main()
53 {
54     string itemIsbn = "x-123-1234-x";
55     Item_base item(itemIsbn,10.0);
56     cout<<item.calMoney(100)<<endl;
57     
58     Bulk_item item2("123-456-x",10.0,30,0.8);
59     cout<<item2.calMoney(100)<<endl;
60     item2.test();
61     
62     Item_base *item3 = new Bulk_item("123-456-789-x",10.0,10,0.8);
63     cout<<item3->calMoney(20)<<endl;
64     //不能调用子类的test方法 
65     return 0;
66 }