更改1_面向过程.cpp

设计模式：工厂模式、单例模式的基本实现

#include <iostream>
using namespace std;

int main()
{
	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;

	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
		{
			cout << "除数不能为0." << endl;
		}
		break;
	}

	cout << "结果是: " << result << endl;

	return 0;
}