1             List<string> arr = new List<string>();
 2             arr.Add("好玩1");
 3             arr.Add("好玩1");
 4             arr.Add("好玩1");
 5             string str = string.Join(",", arr.ToArray());
 6 
 7             ArrayList arr1 = new ArrayList();
 8             arr1.Add("好玩1");
 9             arr1.Add("好玩2");
10             arr1.Add("好玩3");
11             string str1 = string.Join(",", arr1.ToArray(typeof(string)) as string[]);