策略模式C++实现

没有用策略模式的场景

Strategy_origin.cpp

#include<iostream>
#include<string>
using namespace std;


void Runto(string country)
{
    if(country == "Singpore")
    {
        cout<<"Welcome to  Singpore"<<endl;

    }
    else if(country == "Canada" )
    {
        cout<<"Welcome to  Canada"<<endl;

    }
    else if(country == "France" )
    {
        cout<<"Welcome to  France"<<endl;
    }
    else if(country == "German" )
    {
        cout<<"Welcome to  German"<<endl;
    }
    else
    {
        cout<<"Oops! no such choice"<<endl;
    }
}


int main(){
    string destination;
    cin>>destination;
    Runto(destination);
}

使用策略模式的场景

Strategy_modfied.cpp

#include<iostream>
using namespace std;


//策略类
class CountryStrategy
{
    public:
        virtual void printInfo() = 0;

};

class Singpore: public CountryStrategy
{
    public:
        virtual void printInfo(){
            cout<<"welcome to Singpore "<<endl;
        }
};


class France: public CountryStrategy
{
    public:
        virtual void printInfo(){
            cout<<"welcome to France "<<endl;
        }
};

class Canada: public CountryStrategy
{
    public:
        virtual void printInfo(){
            cout<<"welcome to Canada "<<endl;
        }
};

//上下文选择类
class ChooseCountry{
    private:
          CountryStrategy* country;
    public:
      
        ChooseCountry(CountryStrategy* c):country(c){};
        void printInfo(){
            country->printInfo();
        }


};


int main()
{
    Canada*  c = new Canada;
    Singpore*  s = new Singpore;
    ChooseCountry ch(s);
    ch.printInfo();
    delete c;
    delete s;
    c= NULL;
    


}