策略模式

策略模式是最简单的一种模式，就是根据不同子类的需求改写父类的接口实现各自的特性。

示例代码

#include <iostream>
using namespace std;


class ICalculate
{
public:
    virtual void Calculate(int a, int b) = 0;
};
class CalculateAdd: public ICalculate
{
public:
    virtual void Calculate(int a, int b) { cout << (a + b) << endl; }
};
class CalculateSubtract : public ICalculate
{
public:
    virtual void Calculate(int a, int b) { cout << (a - b) << endl; }
};
class CalculateMultiply : public ICalculate
{
public:
    virtual void Calculate(int a, int b) { cout << (a * b) << endl; }
};
class CalculateDivide : public ICalculate
{
public:
    virtual void Calculate(int a, int b)
    {
        if (b)
            cout << (a / b) << endl;
        else
            cout << 0 << endl;
    }
};

int main()
{
    ICalculate* calculate = new CalculateAdd;
    calculate->Calculate(10, 10);
    delete calculate;
    calculate = new CalculateSubtract;
    calculate->Calculate(10, 10);
    delete calculate;
    calculate = new CalculateMultiply;
    calculate->Calculate(10, 10);
    delete calculate;
    calculate = new CalculateDivide;
    calculate->Calculate(10, 10);
    delete calculate;
    calculate = NULL;
    return 0;
}
}