一个将阿拉伯数字转换成中文大写的好算法(C#)

//加到类的定义部分
private static string[] cstr={"零","壹","贰","叁","肆", "伍", "陆","柒","捌","玖"};
private  static string[] wstr={"","","拾","佰","仟","萬","拾","佰","仟","億","拾","佰","仟"};
//数字必须在12位整数以内的字符串
//调用方式如：Label1.Text=ConvertInt("数字字符串");

public string ConvertInt(string str)
  {
  int len=str.Length;
     int i;
  string tmpstr,rstr;
   rstr="";
   for(i=1;i<=len;i++)
   {
   tmpstr=str.Substring(len-i,1);
   rstr=string.Concat(cstr[Int32.Parse(tmpstr)]+wstr[i],rstr);
   }
   rstr=rstr.Replace("拾零","拾");
   rstr=rstr.Replace("零拾","零");
            rstr=rstr.Replace("零佰","零");
            rstr=rstr.Replace("零仟","零");
   rstr=rstr.Replace("零萬","萬");
   for(i=1;i<=6;i++)
   rstr=rstr.Replace("零零","零");
   rstr=rstr.Replace("零萬","零");
   rstr=rstr.Replace("零億","億");
   rstr=rstr.Replace("零零","零"); 
                        rstr+="圆整";  
        return rstr;
  }