public string Generate(int length) { string s = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; string str = ""; Random r = new Random(); for (int i = 0; i < length; i++) { str += s.Substring(r.Next(s.Length), 1); } return str; }