调试易

using System;class Test
{    static void Main()
    {
        Console.WriteLine(GetString("1,2,3,5,8,", 1));//1
        Console.WriteLine(GetString("1,2,3,5,8,", 4));//5
        Console.ReadLine();
    }    static string GetString(string s, int index)
    {
        string[] slist = s.Split(',');        if (--index < 0)
        {
            throw new Exception("....");
        }        if (index >= slist.Length)
        {
            throw new Exception("....");
        }        return slist[index];    }
}

Split(',')
Split(new string[]{","},StringSplitOptions.RemoveEmptyEntries)

   string str = "1,2,3,4,5";
      string[] arr= str.Split(',');
      for (int i = 0; i < arr.Length; i++)
      {          Response.Write(arr[i] + " <br />");
      }
        

string test = "1,2,3,4,5,6";
            string[] test1 = test.Split(new string[] {","},StringSplitOptions.RemoveEmptyEntries);
            StringBuilder sb = new StringBuilder();            foreach (String s in test1)
            {
                sb.Append(s.ToString());
            }
            Response.Write(sb.ToString());
结果123456