C#取中间文本

         /// <summary>
         /// 取中间文本 + static string GetMiddleStr(string oldStr,string preStr,string nextStr)
         /// </summary>
         /// <param name="oldStr">原文</param>
         /// <param name="preStr">前文</param>
         /// <param name="nextStr">后文</param>
         /// <returns></returns>
         public static string GetMiddleStr(string oldStr, string preStr, string nextStr)
         {
             string tempStr = oldStr.Substring(oldStr.IndexOf(preStr) + preStr.Length);
             tempStr = tempStr.Substring(, tempStr.IndexOf(nextStr));
             return tempStr;
         }