C# 统计文章中字符的种类和个数 哈希表和字典的使用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;

namespace Dictionary测试
{
    class Program
    {
        static void Main(string[] args)
        {

           //Hashtable的使用

           Hashtable ht=new Hashtable();
            ht.Add(10141303, "丁小未");
            ht.Add(10141301, "陈立");
            Console.Write("10141301学号对应的同学"+ht[10141301]+"\n");
            //遍历Hashtable
            foreach(DictionaryEntry de in ht) //fileht为一个Hashtable实例
            {
                Console.WriteLine(de.Key);//de.Key对应于keyvalue键值对key
                Console.WriteLine(de.Value);//de.Key对应于keyvalue键值对value
            }

           
            //Dictionary<char, char> dict = new Dictionary<char, char>();
       
            Console.WriteLine("请输入英文：");
            string S = Console.ReadLine();
            string s=S.ToLower();
            Dictionary<char, int> countn = new Dictionary<char, int>();
            //countn.Add('a', 0);
            //countn.Add('b', 0);
            //countn.Add('c', 0);
            //countn.Add('d', 0);
            //countn.Add('e', 0);
            //countn.Add('f', 0);
            //countn.Add('g', 0);
            //countn.Add('h', 0);
            //countn.Add('i', 0);
            //countn.Add('j', 0);
            //countn.Add('k', 0);
            //countn.Add('l', 0);
            //countn.Add('m', 0);
            //countn.Add('n', 0);
            //countn.Add('o', 0);
            //countn.Add('p', 0);
            //countn.Add('q', 0);
            //countn.Add('r', 0);
            //countn.Add('s', 0);
            //countn.Add('t', 0);
            //countn.Add('u', 0);
            //countn.Add('v', 0);
            //countn.Add('w', 0);
            //countn.Add('x', 0);
            //countn.Add('y', 0);
            //countn.Add('z', 0);
            List<char> list = new List<char>();
            foreach (char a in s)
            {
                list.Add(a);
            }
           
            foreach (char v in list)
            {
                //处理标点或者意外字符
                if (countn.ContainsKey(v))
                {
                    countn[v]++;
                }
                else
                {
                    countn.Add(v, 1);
                }
            }
            计算运行时间的函数
            Stopwatch wp = new Stopwatch();
            wp.Start();
            foreach (KeyValuePair<char,int> keyvalue in countn)
            {
                char a = keyvalue.Key;
                int n = keyvalue.Value;
                Console.WriteLine(a +"   " +n);
            }
            wp.Stop();
            Console.WriteLine(wp.Elapsed);

           
            Console.Read();
        }    
                
        #region else输出打印泛型数组
        /// <sum{mary>
        /// 打印    zw += a;输出泛型数组
        /// </su}mmary>
        /// <param name="yuju">要求输出的泛型</param>
        private static void shuchu(List<char> yuju)
        {
            foreach (char a in yuju)
            {
                Console.Write(a);
            }
        }
        #endregion
    }
}