參考http://blog.csdn.net/calmreason/article/details/51029285

定義一系列相同的算法 根據不同需求選擇不同的算法策略

代碼

// 004.cpp: 定義控制臺應用程序的入口點。
//

#include "stdafx.h"
#include <memory>
#include <iostream>

using namespace std;

class Strategy {
public:
    virtual void doAlgorithm(void) = 0;
    virtual ~Strategy(){}
 
protected:

};

class StrategyA :public Strategy
{
    void doAlgorithm(void) { std::cout << __FUNCTION__ << std::endl; }
};

class StrategyB :public Strategy
{
    void doAlgorithm(void) { std::cout << __FUNCTION__ << std::endl; }
};

class UseStrategy
{
public
 
:
    UseStrategy(std::shared_ptr<Strategy> ps) :ps_(ps) {}
    void useAlgorithm(void) {
        std::shared_ptr<Strategy> ps = this->ps_.lock();
        ps->doAlgorithm();
    }
private:
    std::weak_ptr<Strategy> ps_;
};


int main()
{
    std::shared_ptr<Strategy> ps = std::make_shared<StrategyA>();
    UseStrategy user(ps);
    user.useAlgorithm();

    ps 
 
= std::make_shared<StrategyB>();
    UseStrategy user1(ps);
    user1.useAlgorithm();
    return 0;
}

設計模式策略模式