C#实现一个计算器

• 一、运算类
• 二 、加法类
• 三、减法类
• 四、 乘法类
• 五、除法类
• 五、OperationFactory类
• 六、客户端代码

一、运算类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace lianxi
{
   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;
        }
    }
}

在父类中定义 virtual 方法，如果在子类中进行了 override（重写），可以进行多态调用。 如果在子类中未进行 override，程序并不会报错。

二 、加法类

    class OperationAdd:OPeration    //继承运算类
    {
        public override double GetResult()
        {
            double result = 0;
            result = NumberA + NumberB;
            return result;
        }
    }

三、减法类

    class OperationSub :OPeration//继承运算类
    {
        public override double GetResult()
        {
            double result = 0;
            result = NumberA - NumberB;
            return result;
        }
    }

四、 乘法类

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

五、除法类

  class OperationDiv:OPeration
    {
        public override double GetResult()
        {
            double result = 0;
            if (NumberB == 0)
                throw new Exception("除数不可以为零");
            result = NumberA / NumberB;
            return result;
        }
    }

五、OperationFactory类

 class OperationFactory
    {
        public static OPeration createOperate(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;
            }
            return oper;
        }
    }

六、客户端代码

				Console.WriteLine("请输入第一个数字A:");
				double numberA = double.Parse(Console.ReadLine());
				Console.WriteLine("请输入运算符:+ - * /:");
				string symbol = Console.ReadLine();
				Console.WriteLine("请输入第二个数字B:");
				double numberB = double.Parse(Console.ReadLine());
				OPeration oper = OperationFactory.createOperate(symbol);
				oper.NumberA = numberA;
				oper.NumberB = numberB;
				double result = oper.GetResult();
				Console.WriteLine("结果是:"+ result);
				Console.ReadLine();