设计模式之策略模式

#include<iostream>
//策略基类
class Strategy {
public:
    virtual float DoPeration(float num1, float num2) = 0;
};

//加法
class OperationAdd :public Strategy {
public:

    float DoPeration(float num1, float num2) override {
        return num1 + num2;
    }

};

//减法
class OperationSubstract:public Strategy {
public:

    float DoPeration(float num1, float num2) override {
        return num1 - num2;
    }
};

//策略模式使用类
class Context {
    //具体策略
    Strategy* strategy;
public:
    
    Context(Strategy* sty) {
        strategy = sty;
    }

    //改变策略
    void SetStrategy(Strategy* sty) {
        strategy = sty;
    }
    //执行策略
    float ExecuteStrategy(float num1, float num2) {
        return strategy->DoPeration(num1,num2);
    }
};
int main()
{
    Strategy* strategy_add = new OperationAdd();
    Strategy* strategy_substract = new OperationSubstract();

    Context* context = new Context(strategy_add);
    std::cout << "10 +55.55 == " << context->ExecuteStrategy(10, 55.55) << "\n";

    context->SetStrategy(strategy_substract);
    std::cout<<"20 - 100 == "<<context->ExecuteStrategy(20,100)<<"\n";


    system("pause");
}