9、[C++]工厂模式

#include <iostream>
using namespace std;

class Operation {
public:
    virtual double GetResult() = 0;

    double m_dNum_A = 0;
    double m_dNum_B = 0;
};

class OperationAdd : public Operation {
public:
    virtual double GetResult() {
        double dResult = m_dNum_A + m_dNum_B;
        return dResult;
    }
};

class OperationSub : public Operation {
public:
    virtual double GetResult() {
        double dResult = m_dNum_A - m_dNum_B;
        return dResult;
    }
};

class OperationMul : public Operation {
public:
    virtual double GetResult() {
        double dResult = m_dNum_A * m_dNum_B;
        return dResult;
    }
};

class OperationDiv : public Operation {
public:
    virtual double GetResult() {
        double dResult = m_dNum_A / m_dNum_B;
        return dResult;
    }
};

class IFactory {
public:
    virtual Operation* CreateOperate() = 0;
};

class AddFactory
    : public IFactory {
public:
    Operation* CreateOperate() {
        return new OperationAdd();
    }
};

class SubFactory
    : public IFactory {
public:
    Operation* CreateOperate() {
        return new OperationSub();
    }
};

class MulFactory
    : public IFactory {
public:
    Operation* CreateOperate() {
        return new OperationMul();
    }
};

class DivFactory
    : public IFactory {
public:
    Operation* CreateOperate() {
        return new OperationDiv();
    }
};

int _tmain(int argc, _TCHAR* argv[]) {
    IFactory* operFactory = NULL;
    char cOp;
    cout << "请输入操作符(+ - * / . . .):" << endl;
    cin >> cOp;

    switch (cOp) {
    case ‘+‘:
        operFactory = new AddFactory();
        break;
    case ‘-‘:
        operFactory = new SubFactory();
        break;
    case ‘*‘:
        operFactory = new MulFactory();
        break;
    case ‘/‘:
        operFactory = new DivFactory();
        break;
    }
    
    if (operFactory != NULL) {
        Operation* pOper = operFactory->CreateOperate();
        cout << "请输入第一个数:" << endl;
        cin >> pOper->m_dNum_A;
        cout << "请输入第二个数:" << endl;
        cin >> pOper->m_dNum_B;

        try {
            double dResult = pOper->GetResult();
            cout << "结果是: " << dResult << endl;
        } catch (...) {
            cout << "请输入正确操作数" << endl;
        }
    }

    system("PAUSE");
    return 0;
}