当前日期得到本周的开始和结束日期

/// <summary>   /// 本周起止时间   /// </summary>   /// <param name="dt"></param>   /// <returns></returns>   private string weekrange(System.DateTime dt)   {    int weeknow = Convert.ToInt32(dt.DayOfWeek);    int daydiff = (-1) * weeknow;    int dayadd = 6-weeknow;    string datebegin = System.DateTime.Now.AddDays(daydiff).ToString("yyyyMMdd");    string dateend = System.DateTime.Now.AddDays(dayadd).ToString("yyyyMMdd");    return datebegin + " - " +dateend;   }   /// <summary>   /// 返回指定URL的源代码   /// </summary>   /// <param name="url"></param>   private string GetHTML( string url,string tag)   {    byte[] buf = new byte[38192];    System.Net.WebRequest request =  WebRequest.Create(url);;    WebResponse response =request.GetResponse();    Stream resStream = response.GetResponseStream();    int count = resStream.Read(buf, 0, buf.Length);    string result = Encoding.Default.GetString(buf, 0, count);    resStream.Close();    Regex   reg=new   Regex(@"(?<"+tag+">.*?</"+tag+">)",RegexOptions.IgnoreCase);      string   output=reg.Match(result).Value;    return StripHTML(output);   }   /// <summary>   /// 去除HTML标记   /// </summary>   /// <param name="strHtml">包括HTML的源码 </param>   /// <returns>已经去除后的文字</returns>   public static string StripHTML(string strHtml)   {    string [] aryReg ={           @"<script[^>]*?>.*?</script>",           @"<(///s*)?!?((/w+:)?/w+)(/w+(/s*=?/s*(([""'])(file://[""'tbnr]|[^/7])*?/7|/w+)|.{0})|/s)*?(///s*)?>",           @"([/r/n])[/s]+",           @"&(quot|#34);",           @"&(amp|#38);",           @"&(lt|#60);",           @"&(gt|#62);",           @"&(nbsp|#160);",           @"&(iexcl|#161);",           @"&(cent|#162);",           @"&(pound|#163);",           @"&(copy|#169);",           @"&#(/d+);",           @"-->",           @"<!--.*/n"                   };    string [] aryRep = {            "",            "",            "",            "/"",            "&",            "<",            ">",            " ",            "/xa1",//chr(161),            "/xa2",//chr(162),            "/xa3",//chr(163),            "/xa9",//chr(169),            "",            "/r/n",            ""           };    string newReg =aryReg[0];    string strOutput=strHtml;    for(int i = 0;i<aryReg.Length;i++)    {     Regex regex = new Regex(aryReg[i],RegexOptions.IgnoreCase );     strOutput = regex.Replace(strOutput,aryRep[i]);    }    strOutput.Replace("<","");    strOutput.Replace(">","");    strOutput.Replace("/r/n","");    return strOutput;   }