strategy模式

讲的很清楚http://www.cnblogs.com/graphicsme/archive/2011/12/03/2274918.html
 1 #include <iostream>
 2 #include <string>
 3 #include <vector>
 4 #include <queue>
 5 #include <set>
 6 #include <algorithm>
 7 #include <map>
 8 #include <stack>
 9 using namespace std;
10 
11 class SaleStrategy {
12 public:
13     virtual float calculate(float price, int amount) = 0;
14 };
15 
16 class RegularSaleStrategy: public SaleStrategy {
17 public:
18     virtual float calculate(float price, int amount) {
19         return price * amount;
20     }
21 };
22 
23 class StudentSaleStrategy: public SaleStrategy {
24 public:
25     virtual float calculate(float price, int amount) {
26         const float DISCOUNT = 0.5f; //学生半价
27 
28         return (1 - DISCOUNT) * price * amount;
29     }
30 };
31 
32 class BulkSaleStrategy: public SaleStrategy {
33 public:
34     virtual float calculate(float price, int amount) {
35         const float DISCOUNT = 0.3f; //批发折扣
36         const int BULK_LIMIT = 100; //>=100件按批发价
37 
38         if (amount >= BULK_LIMIT)
39             return (1 - DISCOUNT) * price * amount;
40         return price * amount;
41     }
42 };
43 
44 class SaleManager {
45 public:
46     SaleManager(SaleStrategy* pSaleStrategy = NULL) :
47             m_pSaleStrategy(pSaleStrategy) {
48     }
49 
50 public:
51     void setStrategy(SaleStrategy* pSaleStrategy) {
52         m_pSaleStrategy = pSaleStrategy;
53     }
54 
55     float calculateTotal(float price, int amount) {
56         float calResult = m_pSaleStrategy->calculate(price, amount);
57         cout << "total price is: " << calResult << endl;
58         return calResult;
59     }
60 
61 private:
62     SaleStrategy* m_pSaleStrategy;
63 };
64 int main(int argc, char** argv) {
65     SaleStrategy* pSaleStrategy = new RegularSaleStrategy();
66     SaleStrategy* pStudentSaleStrategy = new StudentSaleStrategy();
67     SaleStrategy* pBulkSaleStrategy = new BulkSaleStrategy();
68 
69     SaleManager saleManager(pSaleStrategy);
70     cout << "Regular Sale Strategy:\n";
71     saleManager.calculateTotal(2.5f, 100);
72 
73     saleManager.setStrategy(pStudentSaleStrategy);
74     cout << "Student Sale Strategy:\n";
75     saleManager.calculateTotal(2.5f, 100);
76 
77     saleManager.setStrategy(pBulkSaleStrategy);
78     cout << "Bulk Sale Strategy:\n";
79     saleManager.calculateTotal(2.5f, 100);
80 
81     delete pBulkSaleStrategy;
82     delete pStudentSaleStrategy;
83     delete pSaleStrategy;
84 
85     return 0;
86 }