记录、c++函数重写失败——虚函数的多态要用指针调用

先写了个基类，里面有虚函数

class Operation
{
public:
	//result 结果
	virtual double GetResult() {
		double result = 0;
		return result;
	}

	double _numberA = 0;
	double _numberB = 0;
private:
};

然后我是这么重写的

class OperationAdd : public Operation
{
public:
	 double GetResult() override {
		 double result = 0;
		 result = _numberA + _numberB;
		 return result;
	}
};

多态函数写的我一头雾水，就把他向下转换就能直接重写了吗，可是后面运行时候还是调用的基类函数= =

class OperationFactor
{
public:
	static Operation* createOperate(char operate) {
		Operation* oper=NULL;
		switch (operate)
		{
		case '+':
			oper = new OperationAdd();
			break;
		case '-':
			oper = new OperationSub();
			break;
		case '*':
			oper = new OperationMul();
			break;
		case '/':
			oper = new OperationDiv();
			break;
		}
		return oper;
	}		
};

最后是客户端代码：

		Operation *oper=new Operation();
		char operate;
	
		cout << "请输入所需运算符： + - * /" << endl;
		cin >> operate;
		oper = (new OperationFactor)->createOperate(operate);
		cout << "请输入数字1:" << endl;
		cin >> oper->_numberA;
		cout << "请输入数字2:" << endl;
		cin >>oper->_numberB;		
		double result = oper.GetResult();
		cout <<"运算结果为：" << result;```