c++设计模式：策略模式

#include <iostream>
using namespace std;
 
// The abstract strategy
class Strategy
{
public:
     virtual void AlgorithmInterface() = 0;
};
 
class ConcreteStrategyA : public Strategy
{
public:
     void AlgorithmInterface()
     {
          cout<<"I am from ConcreteStrategyA."<<endl;
     }
};
 
class ConcreteStrategyB : public Strategy
{
public:
     void AlgorithmInterface()
     {
          cout<<"I am from ConcreteStrategyB."<<endl;
     }
};
 
class ConcreteStrategyC : public Strategy
{
public:
     void AlgorithmInterface()
     {
          cout<<"I am from ConcreteStrategyC."<<endl;
     }
};
 
class Context
{
public:
     Context(Strategy *pStrategyArg) : pStrategy(pStrategyArg)
     {
     }
     void ContextInterface()
     {
          pStrategy->AlgorithmInterface();
     }
private:
     Strategy *pStrategy;
};
 
int main()
{
     // Create the Strategy
     Strategy *pStrategyA = new ConcreteStrategyA;
     Strategy *pStrategyB = new ConcreteStrategyB;
     Strategy *pStrategyC = new ConcreteStrategyC;
     Context *pContextA = new Context(pStrategyA);
     Context *pContextB = new Context(pStrategyB);
     Context *pContextC = new Context(pStrategyC);
     pContextA->ContextInterface();
     pContextB->ContextInterface();
     pContextC->ContextInterface();
 
     if (pStrategyA) delete pStrategyA;
     if (pStrategyB) delete pStrategyB;
     if (pStrategyC) delete pStrategyC;
 
     if (pContextA) delete pContextA;
     if (pContextB) delete pContextB;
     if (pContextC) delete pContextC;
}