[学习][笔记]设计模式（基于C/C++实现）＜三＞策略模式

//strategy.h
#ifndef STRATEGY_H
#define STRATEGY_H
class Strategy {
public:
    virtual int DoOperation(int num1, int num2) = 0;
};
#endif // STRATEGY_H
//strategy_add.h
#ifndef STRATEGY_ADD_H
#define STRATEGY_ADD_H
#include <strategy.h>
class StrategyAdd :public Strategy{
    int DoOperation(int num1, int num2) override;
};
int StrategyAdd::DoOperation(int num1,int num2){
    return num1+num2;
}
#endif // STRATEGY_ADD_H
//strategy_multiply.h
#ifndef STRATEGY_MULTIPLY_H
#define STRATEGY_MULTIPLY_H
#include <strategy.h>
class StrategyMultiply :public Strategy
{
    int DoOperation(int num1, int num2) override;
};
int StrategyMultiply::DoOperation(int num1,int num2){
    return num1*num2;
}
#endif // STRATEGY_MULTIPLY_H
//strategy_substract.h
#ifndef STRATEGY_SUBSTRACT_H
#define STRATEGY_SUBSTRACT_H
#include <strategy.h>
class StrategySubstract :public Strategy
{
    int DoOperation(int num1, int num2) override;
};
int StrategySubstract::DoOperation(int num1, int num2){
    return num1 - num2;
}
#endif // STRATEGY_SUBSTRACT_H
//context.h
#ifndef CONTEXT_H
#define CONTEXT_H
#include <strategy.h>
class Context
{
private:
    Strategy *ptrStrategy;
public:
    Context(Strategy *ptr){
        ptrStrategy = ptr;
    }
    ~Context(){
        delete ptrStrategy;
    }
    int ExecuteStrategy(int num1, int num2){
       return ptrStrategy->DoOperation(num1,num2);
    }
};
#endif // CONTEXT_H
//main.cpp
#include <iostream>
#include <context.h>
#include <strategy.h>
#include <strategy_add.hpp>
#include <strategy_substract.hpp>
#include <strategy_multiply.h>
#include <iostream>
using namespace std;
int main()
{
    Context *ptrContextAdd = new Context(new StrategyAdd);
    int addRet = ptrContextAdd->ExecuteStrategy(2,2);
    cout<<"add = result:"<<addRet<<endl;
    Context *ptrContextSub = new Context(new StrategySubstract);
    int subRet = ptrContextSub->ExecuteStrategy(2,2);
    cout<<"substract result:"<<subRet<<endl;
    Context *ptrContextMul = new Context(new StrategyMultiply);
    int mulRet = ptrContextMul->ExecuteStrategy(2,2);
    cout<<"multiple result:"<<mulRet<<endl;
    return 0;
}
输出：
add = result:4
substract result:0
multiple result:4