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:

#pragma once

#include<iostream>
#include<string>

using namespace std;

class Operation
{
 public:
    virtual double GetResult(){return 0};  
public:
    double numA_;
    double numB_;
};

class OperationAdd :public Operation
{
public:
    virtual double GetResult()
    {
        return numA_+numB_;
    }
}

class OperationSub: public Operation
{
public:
    virtual double GetResult()
    {
        return numA_ - numB_;
    }
};

class OperationFactory    //工厂
{
public:
    Operation* CreateOperation(tstring oper)
    {
        Operation*op = NULL;
        if(wcscmp(oper.c_str(),L"+") == 0)
            op = new OperationAdd();
        else
            op = new OperationSub();
        return op;
    }
};

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