工厂模式

#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;
    }
};

class ICalculateFactory
{
public:
    virtual ICalculate* CreateCalculate() = 0;
};
class CalculateAddFactory : public ICalculateFactory
{
public:
    virtual ICalculate* CreateCalculate() { return new CalculateAdd(); }
};
class CalculateSubtractFactory : public ICalculateFactory
{
public:
    virtual ICalculate* CreateCalculate() { return new CalculateSubtract(); }
};
class CalculateMultiplyFactory : public ICalculateFactory
{
public:
    virtual ICalculate* CreateCalculate() { return new CalculateMultiply(); }
};
class CalculateDivideFactory : public ICalculateFactory
{
public:
    virtual ICalculate* CreateCalculate() { return new CalculateDivide(); }
};

int main()
{
    ICalculateFactory* factory = new CalculateAddFactory;
    ICalculate* calculate = factory->CreateCalculate();
    calculate->Calculate(10, 10);
    delete factory;
    delete calculate;
    factory = new CalculateSubtractFactory;
    calculate = factory->CreateCalculate();
    calculate->Calculate(10, 10);
    delete factory;
    delete calculate;
    factory = new CalculateMultiplyFactory;
    calculate = factory->CreateCalculate();
    calculate->Calculate(10, 10);
    delete factory;
    delete calculate;
    factory = new CalculateDivideFactory;
    calculate = factory->CreateCalculate();
    calculate->Calculate(10, 10);
    delete factory;
    delete calculate;
    return 0;
}