设计模式(1):简单工厂模式

根据传入的参数的不同，自动生成需要的类的对象

简单工厂模式只是解决对象的创建问题

Operation.h:

 1 #pragma once
 2 
 3 #include<iostream>
 4 #include<string>
 5 
 6 using namespace std;
 7 
 8 class Operation
 9 {
10  public:
11     virtual double GetResult(){return 0};  
12 public:
13     double numA_;
14     double numB_;
15 };
16 
17 class OperationAdd :public Operation
18 {
19 public:
20     virtual double GetResult()
21     {
22         return numA_+numB_;
23     }
24 }
25 
26 class OperationSub: public Operation
27 {
28 public:
29     virtual double GetResult()
30     {
31         return numA_ - numB_;
32     }
33 };
34 
35 class OperationFactory    //工厂
36 {
37 public:
38     Operation* CreateOperation(tstring oper)
39     {
40         Operation*op = NULL;
41         if(wcscmp(oper.c_str(),L"+") == 0)
42             op = new OperationAdd();
43         else
44             op = new OperationSub();
45         return op;
46     }
47 };

main.cpp

#define _CRTDBG_MAP_ALLOC
#include<stdlib.h>
#include<crtdbg.h>
#include"Operation.h"

int main()
{
    OperationFactory fac;
    Operation* op = fac.CreateOperation(L"+");
    op->numA_ = 20;
    op->numB_ = 30;
    cout << op->GetResult() << "
";
    delete op;
    
    _CrtDumpMemoryLeaks();
    system("pause");
    return 0;
}

输出结果50