使用面向对象的编程思想写一个简单的控制台计算器程序，放松一下
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Calculator2
{
class Program
{
static void Main(string[] args)
{
Operation oper;
oper = OperationFactory.createOpearate("+");
Console.WriteLine("请输入_numberA:");
oper.NumberA =Convert.ToDouble(Console.ReadLine());
Console.WriteLine("请输入_numberB:");
oper.NumberB =Convert.ToDouble(Console.ReadLine());
double result = oper.GetResult();
Console.WriteLine("结果是：{0}",result);
Console.ReadLine();
}
}

public class Operation
{
private double _numberA = 0;
private double _numberB = 0;

public double NumberA
{
get { return _numberA;}
set { _numberA = value; }
}

public double NumberB
{
get { return _numberB; }
set { _numberB = value; }
}

public virtual double GetResult()
{
double result = 0;
return result;
}
}

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

class OperationSub : Operation
{
public override double GetResult()
{
double result = 0;
result = NumberA - NumberB;
return result;
}
}

class OperationMul : Operation
{
public override double GetResult()
{
double result = 0;
result = NumberA * NumberB;
return result;
}
}

class OperationDiv : Operation
{
public override double GetResult()
{
double result = 0;
result = NumberA / NumberB;
return result;
}
}

public class OperationFactory
{
public static Operation createOpearate(string 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;
default:
break;
}
return oper;
}

}
}