asp.net 正则 例子

using System.Text.RegularExpressions; //正则

string strHtml = " </ul> <div id=\"photo-tags\"> <h3 id=\"tags-title\">Tags in this photo: </h3> 

<ul id='tags'> 

<li> <a href='/user/669345/tags/Belgium'>Belgium </a> </li> 

<li> <a href='/user/669345/tags/Belgien'>Belgien </a> </li> 

<li> <a href='/user/669345/tags/Urlaub'>Urlaub </a> </li> 

<li> <a href='/user/669345/tags/Holidays'>Holidays </a> </li> 

<li> <a href='/user/669345/tags/Vakanties'>Vakanties </a> </li> 

<li> <a href='/user/669345/tags/CenterParcs'>CenterParcs </a> </li>

<li> <a href='/user/669345/tags/10 000 000'>10 000 000 </a> </li>

</ul> </div> <div id=\"photo-info\">";

      TextBox1.Text = "" + strHtml + "";

      Regex re = new Regex("(?<=<li> <a href='/user/[^>]*/tags/[^>]*>).*?(?= </a> </li>)");

      if (re.IsMatch(strHtml))
      {
          MatchCollection mc = re.Matches(strHtml);
          foreach (Match ma in mc)
          {
              for (int i = 0; i < ma.Groups.Count; i++)
              {
                  TextBox2.Text += ma.Groups[i].Value + " ";
              }
              TextBox2.Text += "\n";
          }
      }
      else
      {
          TextBox2.Text = "no";
      }

结果：

Belgium
Belgien
Urlaub
Holidays
Vakanties
CenterParcs
10 000 000

/// <summary>
/// 从文章内容中获取第一张图片，用作文章缩略图
/// </summary>
/// <param name="articleContent"></param>
/// <returns></returns>
public static string GetImageUrlFromArticle(string articleContent)
{
    Regex r = new Regex(@"<IMG[^>]+src=\s*(?:'(?<src>[^']+)'|""(?<src>[^""]+)""|(?<src>[^>\s]+))\s*[^>]*>", RegexOptions.IgnoreCase);
    MatchCollection mc = r.Matches(articleContent);
    if (mc.Count != 0)
    {
        return mc[0].Groups["src"].Value.ToLower();
    }
    else
    {
        return "";
    }
}