C#根据规则生成6位随机码

     #region 获得6位优惠码 zhy
     public static string CreatePromoCode(string code)
     {
         if (code == "")
         {
             return "a00001";
         }
         else
         {
             string new_code = "";
             new_code = CreateGrapheme(code);
             new_code += CreateNumber(code);
             return new_code;
         }
     }
     #endregion

     #region 拼接字母 zhy
     public static string CreateGrapheme(string code)
     {
         string new_code = "";
         //获取字母
         string grapheme = GetGrapheme(code);
         //获得数字
         string num = GetNumber(code);
         //最后一个字母为z从新拼接否则获取该字母下一个字母拼接
         if (grapheme.Substring(grapheme.Length - ) == "Z")
         {
             switch (grapheme.Length)
             {
                 case :
                     if (Convert.ToInt32(num) >= )
                     {
                         new_code = "AA";
                     }
                     else
                     {
                         new_code += grapheme;
                     }
                     break;
                 case :
                     if (Convert.ToInt32(num) >= )
                     {
                         new_code = "AAA";
                     }
                     else
                     {
                         new_code += grapheme;
                     }
                     break;
                 case :
                     if (Convert.ToInt32(num) >= )
                     {
                         new_code = "AAAA";
                     }
                     else
                     {
                         new_code += grapheme;
                     }
                     break;
                 case :
                     if (Convert.ToInt32(num) >= )
                     {
                         new_code = "AAAAA";
                     }
                     else
                     {
                         new_code += grapheme;
                     }
                     break;
             }
         }
         else
         {
             switch (grapheme.Length)
             {
                 case :
                     if (Convert.ToInt32(num) >= )
                     {
                         char new_grapheme = Convert.ToChar(Convert.ToInt16(grapheme.Substring(new_code.Length - ).ToCharArray()[]) + );
                         new_code += grapheme.Substring(, new_code.Length - ) + new_grapheme.ToString();
                         num = "";
                     }
                     else
                     {
                         new_code += grapheme;
                     }
                     break;
                 case :
                     if (Convert.ToInt32(num) >= )
                     {
                         char new_grapheme = Convert.ToChar(Convert.ToInt16(grapheme.Substring(new_code.Length - ).ToCharArray()[]) + );
                         new_code += grapheme.Substring(, new_code.Length - ) + new_grapheme.ToString();
                         num = "";
                     }
                     else
                     {
                         new_code += grapheme;
                     }
                     break;
                 case :
                     if (Convert.ToInt32(num) >= )
                     {
                         char new_grapheme = Convert.ToChar(Convert.ToInt16(grapheme.Substring(new_code.Length - ).ToCharArray()[]) + );
                         new_code += grapheme.Substring(, new_code.Length - ) + new_grapheme.ToString();
                         num = "";
                     }
                     else
                     {
                         new_code += grapheme;
                     }
                     break;
                 case :
                     if (Convert.ToInt32(num) >= )
                     {
                         char new_grapheme = Convert.ToChar(Convert.ToInt16(grapheme.Substring(new_code.Length - ).ToCharArray()[]) + );
                         new_code += grapheme.Substring(, new_code.Length - ) + new_grapheme.ToString();
                         num = "";
                     }
                     else
                     {
                         new_code += grapheme;
                     }
                     break;
                 case :
                     if (Convert.ToInt32(num) >= )
                     {
                         char new_grapheme = Convert.ToChar(Convert.ToInt16(grapheme.Substring(new_code.Length - ).ToCharArray()[]) + );
                         new_code += grapheme.Substring(, new_code.Length - ) + new_grapheme.ToString();
                         num = "";
                     }
                     else
                     {
                         new_code += grapheme;
                     }
                     break;
             }
         }
         return new_code;
     }
     #endregion

     #region 获得字母 zhy
     public static string GetGrapheme(string code)
     {
         //定义获取字母的正则
         Regex grapheme_regex = new Regex(@"[A-Z]+");
         //找到字符串中的匹配项
         Match grapheme_match = grapheme_regex.Match(code);
         return grapheme_match.Value;
     }
     #endregion

     #region 获得数字 zhy
     public static string GetNumber(string code)
     {
         //定义获取数字的正则
         Regex num_regex = new Regex(@"[^\d.\d]");
         //剔除字符串中除数字以外的字符
         string num = Regex.Replace(code, @"[^\d.\d]", "").ToString();
         return num;
     }
     #endregion

     #region 拼接数字 zhy
     public static string CreateNumber(string code)
     {
         string new_code = "";
         //获取字母
         string grapheme = GetGrapheme(code);
         //获得数字
         string num = GetNumber(code);

         int old_num = Convert.ToInt32(num);
         //计算字母后的数字
         switch (num.ToString().Length)
         {
             case :
                 if (old_num < )
                 {
                     new_code = new_code + (old_num++);
                 }
                 else
                 {
                     //优惠码已经配到头
                     new_code = "";
                 }
                 break;
             case :
                 if (old_num < )
                 {
                     int temporary_num = old_num;
                     temporary_num++;
                     //判断数字是否从01开始
                     if (temporary_num.ToString().Length == )
                     {
                         new_code = new_code + "" + temporary_num.ToString();
                     }
                     else
                     {
                         new_code = new_code + temporary_num.ToString();
                     }
                 }
                 else
                 {
                     //优惠码已经配到头
                     new_code = new_code + "";
                 }
                 break;
             case :
                 if (old_num < )
                 {
                     int temporary_num = old_num;
                     temporary_num++;
                     //判断数字是否从01开始
                     if (temporary_num.ToString().Length == )
                     {
                         new_code = new_code + "" + temporary_num.ToString();
                     }
                     else if (temporary_num.ToString().Length == )
                     {
                         new_code = new_code + "" + temporary_num.ToString();
                     }
                     else
                     {
                         new_code = new_code + temporary_num.ToString();
                     }
                 }
                 else
                 {
                     //优惠码已经配到头
                     new_code = "";
                 }
                 break;
             case :
                 if (old_num < )
                 {
                     int temporary_num = old_num;
                     temporary_num++;
                     //判断数字是否从01开始
                     if (temporary_num.ToString().Length == )
                     {
                         new_code = new_code + "" + temporary_num.ToString();
                     }
                     else if (temporary_num.ToString().Length == )
                     {
                         new_code = new_code + "" + temporary_num.ToString();
                     }
                     else if (temporary_num.ToString().Length == )
                     {
                         new_code = new_code + "" + temporary_num.ToString();
                     }
                     else
                     {
                         new_code = new_code + temporary_num.ToString();
                     }
                 }
                 else
                 {
                     //优惠码已经配到头
                     new_code = "";
                 }
                 break;
             case :
                 if (old_num < )
                 {
                     int temporary_num = old_num;
                     temporary_num++;
                     //判断数字是否从01开始
                     if (temporary_num.ToString().Length == )
                     {
                         new_code = new_code + "" + temporary_num.ToString();
                     }
                     else if (temporary_num.ToString().Length == )
                     {
                         new_code = new_code + "" + temporary_num.ToString();
                     }
                     else if (temporary_num.ToString().Length == )
                     {
                         new_code = new_code + "" + temporary_num.ToString();
                     }
                     else if (temporary_num.ToString().Length == )
                     {
                         new_code = new_code + "" + temporary_num.ToString();
                     }
                     else
                     {
                         new_code = new_code + temporary_num.ToString();
                     }
                 }
                 else
                 {
                     //优惠码已经配到头
                     new_code = "";
                 }
                 break;
         }
         return new_code;
     }
     #endregion