正则表达式如何提取值
<$if:classid value="1">
<li><a href="{#URL}" target="_blank" title="{uTitle}">{#sTitle}</a></li>
<$else>
<li>{#sTitle}（欢迎）</li>
</$if>

我想提取数  classid  1
以及
<li><a href="{#URL}" target="_blank" title="{uTitle}">{#sTitle}</a></li>
 和
<li>{#sTitle}（欢迎）</li>

Regex reg = new Regex(@"(?is)<\$if:(?<name>.*?)\s+value=""(?<value>.*?)"">(\\s*?<li1>.*)<$else>(\\s*?<li2>.*^($if))</\$if>");
            MatchCollection mc = reg.Matches(mass);
            int shtml = mc.Count;
            foreach (Match match in mc)
            {
                string name = match.Groups["name"].Value.Trim();
                string value = match.Groups["value"].Value.Trim();
                string li1 = match.Groups["li1"].Value.Trim();
                string li2 = match.Groups["li2"].Value.Trim();
                //System.Web.HttpContext.Current.Response.Write(name + "<br/>");
                //System.Web.HttpContext.Current.Response.Write(value + "<br/>");
            }  我这样写了 提取不出来

正则改成这样 按照你那样取值就对了
(?is)<\$if:(?<name>\w+)\s+value=""(?<value>[^""]*?)"">\s*(?<li1>(<li>.*?</li>))\s*<\$else>\s*(?<li2>(<li>.*?</li>))\s*</\$if>