sdaf;adsfad;dd;dee;ddd; 删除;号时删除前面的字符 例如删除第3个;就删除dd;
删除后变为sdaf;adsfad;dee;ddd;
谢谢 c# string 删除
[解决办法]

string str = "sdaf;adsfad;dd;dee;ddd;";
int n = 4;
str = Regex.Replace(str,@"(?<=^(\w+;){"+(n-1)+@"})\w+;", "");

[解决办法]

private string Delete(string str, int delIndex)
     {
         string[] arry = str.Split(';');
         if (delIndex > arry.Length)
             return str;
         string strRet = string.Empty;
         for (int i = 0; i < arry.Length; i++)
         {
             if (i + 1 != delIndex)
             {
                 strRet += arry[i];
                 if (i < arry.Length - 1)
                     strRet += ";";
             }
         }
         return strRet;
     }

  string str = "sdaf;adsfad;dd;dee;ddd;";
        str = Delete(str, 3);