将字符串"123456"转换成"1,2,3,4,5,6"

         ///   <summary>
         ///  将字符串"123456"转换成"1,2,3,4,5,6"
         ///   </summary>
         ///   <param name="code"> 要转换的字符串 </param>
         ///   <returns> 转换结果 </returns>
         protected  string ConvertString( string code)
        {
             string result =  string.Empty;
             for ( int i =  0; i < code.Length; i++)
            {
                result +=  string.Format( " {0}, ", code.Substring(i,  1));
            }
             return result.Remove(result.Length -  1);
        }