C# ascii码与字符的转换

using System;
using System.Text;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("输入要转为ascii码的字符");
            string a = Console.ReadLine();  //接收字符串
            try
            {
                Console.WriteLine(Asc(a));  //将字符串转为ascii码并打印
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
            }
            Console.WriteLine("输入要转为字符的ascii码");
            string b = Console.ReadLine();  //接收ascii码
            try
            {
                Console.WriteLine(Cha(b));  //将ascii码字符串转为并打印
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
            }
        }

        /*字符转ascii码*/
        private static int Asc(string s)
        {
            if (s.Length == 1)
            {
                ASCIIEncoding a = new ASCIIEncoding();
                int b = (int)a.GetBytes(s)[0];  //利用ASCIIEncoding类的GetByte()方法转码
                return b;
            }
            else
            {
                throw new Exception("String is not vaild");
            }
        }

        /*ascii码转字符*/
        private static char Cha(string s)
        {
            int a = int.Parse(s);   //现将字符串转成int类型
            if (a >= 0 && a <= 255)     //若不在这个范围内，则不是字符
            {
                char c = (char)a;   //利用类型强转得到字符
                return c;
            }
            else
            {
                throw new Exception("String is not vaild");
            }
        }
    }
}