C++ 简单工厂模式实现加减运算

class Operator {
protected:
    int firstParameter;
    int secondParameter;
public:
    Operator(int firstP, int secondP) : firstParameter(firstP), secondParameter(secondP) {}
    virtual int getResult() = 0;
};

class Add : public Operator {
public:
    Add(int firstP, int secondP) : Operator(firstP, secondP) {}
    int getResult() override {
        return firstParameter + secondParameter;
    }
};

class Sub : public Operator {
public:
    Sub(int firstP, int secondP) : Operator(firstP, secondP) {}
    int getResult() override {
        return firstParameter - secondParameter;
    }
};

class OperatorSimpleFactory {
public:
    static Operator* createOperator(std::string oper, int firstP, int secondP) {
        if (oper == '+') {
            return new Add(firstP, secondP);
        } else {
            return new Sub(firstP, secondP);
        }
    }
};

int main() {
    std::string oper = "";
    int firstP;
    int secondP;

    std::cout << '请输入想要进行的操作：' << std::endl;
    std::cin >> oper;

    std::cout << '请输入操作数1：' << std::endl;
    std::cin >> firstP;

    std::cout << '请输入操作数2：' << std::endl;
    std::cin >> secondP;

    Operator* op = OperatorSimpleFactory::createOperator(oper, firstP, secondP);

    std::cout << op->getfirstP() << oper << op->getsecondP() << '=' << op->getResult() << std::endl;

    std::cout << '运行结束' << std::endl;

    return 0;
}