string[] Convert(string[] items) { List<string> ls = new List<string>(); foreach (string item in items) { string[] arr = item.Split('-'); foreach (string s in arr[1].Split(',')) ls.Add(item[0] + "-" + s); } string[] result = new string[ls.Count]; for (int i = 0; i < ls.Count; i++) result[i] = ls[i]; return result; }