實現園、長方形和直角三角形3種圖形的面積計算！

using System;
using System.Collections.Generic;
using System.Text;

namespace Area
{
    public class myArea
    {
        int index = 0;     //設置用戶選擇參數
        private const double PI = 3.1415;    //PI值
        double a, b;       //面積計算方法參數
        public static double Squre(double a, double b)
        {
            return a * b;
        }
        public static double Sanjiao(double a, double b)
        {
            return (a * b) / 2;
        }
        public static double Circle(double a)
        {
            return PI * a * a;
        }
        public myArea()
        {
            Console.WriteLine("選擇何種圖形的計算？");
            Console.WriteLine("1.矩形");
            Console.WriteLine("2.直角三角形");
            Console.WriteLine("3.圓形");
            switch (index = Convert.ToInt16(Console.ReadLine()))
            {
                case 1:
                    {
                        Console.Write("你選擇的是計算矩形，請輸入矩形的長：");
                        a = Convert.ToDouble(Console.ReadLine());
                        Console.Write("你請輸入矩形的寬：");
                        b = Convert.ToDouble(Console.ReadLine());
                        Console.WriteLine("矩形的面積爲：{0}", Squre(a, b));
                        break;
                    }
                case 2:
                    {
                        Console.Write("你選擇的是計算直角三角形，請輸入三角形的一條直角邊：");
                        a = Convert.ToDouble(Console.ReadLine());
                        Console.Write("你請輸入另一條邊：");
                        b = Convert.ToDouble(Console.ReadLine());
                        Console.WriteLine("三角形的面積爲：{0}", Sanjiao(a, b));
                        break;
                    }
                case 3:
                    {
                        Console.Write("你選擇的是圓形，請輸入圓的半徑：");
                        a = Convert.ToDouble(Console.ReadLine());
                        Console.WriteLine("圓形的面積爲：{0}", Circle(a));
                        break;
                    }
            }
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            myArea mya = new myArea();
        }
    }
}

 

//namespace Area
//{
//    public class myArea
//    {
//        int index = 0;     //設置用戶選擇參數
//        private const double PI = 3.1415;    //PI值
//        double a, b;       //面積計算方法參數
//        public  double Squre(double a, double b)
//        {
//            return a * b;
//        }
//        public double Sanjiao(double a, double b)
//        {
//            return (a * b)/2;
//        }
//        public double Circle(double a)
//        {
//            return PI*a * a;
//        }
//        public void panduan()
//        {
//            switch (index = Convert.ToInt16(Console.ReadLine()))
//            {
//                case 1:
//                    {
//                        Console.Write("你選擇的是計算矩形，請輸入矩形的長：");
//                        a = Convert.ToDouble(Console.ReadLine());
//                        Console.Write("你請輸入矩形的寬：");
//                        b = Convert.ToDouble(Console.ReadLine());
//                        Console.WriteLine("矩形的面積爲：{0}",Squre(a,b));
//                        break;
//                    }
//                case 2:
//                    {
//                        Console.Write("你選擇的是計算直角三角形，請輸入三角形的一條直角邊：");
//                        a = Convert.ToDouble(Console.ReadLine());
//                        Console.Write("你請輸入另一條邊：");
//                        b = Convert.ToDouble(Console.ReadLine());
//                        Console.WriteLine("三角形的面積爲：{0}", Sanjiao(a, b));
//                        break;
//                    }
//                case 3:
//                    {
//                        Console.Write("你選擇的是圓形，請輸入圓的半徑：");
//                        a = Convert.ToDouble(Console.ReadLine());
//                        Console.WriteLine("圓形的面積爲：{0}", Circle(a));
//                        break;
//                    }
//            }
//        }
//    }
//    class Program
//    {
//        static void Main(string[] args)
//        {
//            myArea mya = new myArea();
//            Console.WriteLine("選擇何種圖形的計算？");
//            Console.WriteLine("1.矩形");
//            Console.WriteLine("2.直角三角形");
//            Console.WriteLine("3.圓形");
//            mya.panduan();
//        }
//    }
//}