MFC——工厂模式——计算器

</pre><pre name="code" class="cpp"><img src="https://img-blog.youkuaiyun.com/20160519203716268?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" />

</pre><pre name="code" class="cpp"><span style="font-size:18px;color:#ff0000;"><strong>一、先创建Operation.h</strong></span>

<span style="font-size:18px;">#pragma once

#include <iostream>
using namespace std;
class Operation {
private:
	double _numberA = 0;
	double _numberB = 0;

public:
	double get_A(){ return _numberA; }
	double get_B(){ return _numberB; }
	void set_A(double value) { _numberA = value; }
	void set_B(double value){ _numberB = value; }
	virtual double GetResult(){
		double result = 0;
		return result;
};

};
class OperationAdd :public Operation
{
public:
	double GetResult(){
		double result = 0;
		result = get_A() + get_B();
		return result;
	}
};
class OperationSub :public Operation
{
public:
	double GetResult(){
		double result = 0;
		result = get_A() - get_B();
		return result;
	}
};
/// <summary>
///      
/// </summary>
class OperationMul :public Operation
{
public:
	double GetResult(){
		double result = 0;
		result = get_A() * get_B();
		return result;
	}
};
/// <summary>
///       
/// </summary>
class OperationDiv :public Operation
{
public:
	double GetResult(){
		double result = 0;
		if (get_B() == 0)
			throw("除数不能为0");
		result = get_A() / get_B();
		return result;
	}
};
/// <summary>
///         
/// </summary>
class OperationFactory
{
public:
	static Operation* createOperate(char operate) {
		Operation *oper = NULL;
		switch (operate) {
			case 'a': {
				oper = new OperationAdd();
				break;
			}
			case 'b': {
				oper = new OperationSub();
				break;
			}
			case 'c': {
				oper = new OperationMul();
				break;
			}
			case 'd': {
				oper = new OperationDiv();
				break;
			}
		}
		return oper;
	}
};</span>

<span style="font-size:18px;">
</span>

<span style="font-size:18px;color:#ff0000;"><strong>二、在MainDlg.cpp添加事件处理函数</strong></span>

<span style="font-size:18px;">
</span>

<span style="font-size:18px;">void CCalculatorDlg::OnBnClickedButton3()
{
	// TODO: 在此添加控件通知处理程序代码
	UpdateData(TRUE);
	Operation *oper = OperationFactory::createOperate('a');
	oper->set_A(data1);
	oper->set_B(data2);
	data3 = oper->GetResult();
	UpdateData(FALSE);
}
</span>

写出来感觉怪怪的，求哪位大神指点一下，这是我们的暑假考试作业

主要是那个工厂模式怎么写和调用问题。