更改2_面向对象_业务界面逻辑分离.cpp

设计模式：工厂模式、单例模式的基本实现

#include <iostream>
using namespace std;

// 操作类中的操作与界面操作分离
class Operation
{
public:
	static double GetResult(double, double, char);
};

double Operation::GetResult(double numberA, double numberB, char operate)
{
	double result = 0;
	
	switch(operate)
	{
	case '+':
		result = numberA + numberB;
		break;
	case '-':
		result = numberA - numberB;
		break;
	case '*':
		result = numberA * numberB;
		break;
	case '/':
		if(numberB != 0)
		{
			result = numberA / numberB;
		}
		else
		{
			throw "除数不能为0";
		}
		break;
	}
	return result;
}


int main()
{
	try
	{
		double numberA;
		cout << "请输入数字numberA :";
		cin >> numberA;

		double numberB;
		cout << "请输入数字numberB :";
		cin >> numberB;

		char operate;
		cout << "请输入操作符operate :";
		cin >> operate;

		double result = 0;

		result = Operation::GetResult(numberA, numberB, operate);

		cout << "结果是: " << result << endl;
	}
	catch(const char* msg)
	{
		cout << msg << endl;
	}

	return 0;
}