生成n位隨機驗證碼，程式碼如下：

 public static string RandomCode(int n)
 {
      int number;
      char code;
      string StrCode = String.Empty;
      Random random = new Random();
      for (int i = 0; i < n; i++)
      {
          number = random.Next();
          if (number % 2 == 0)
          code = (char)('0' + (char)(number % 10));
          else
          code = (char)('A' + (char)(number % 26));
          StrCode += code.ToString();
      }
      return StrCode;
}