我如何获得所有同级ul标签？

Question

下面是一个HTML片段： 来自：http://www.sphere-light.com/compatibility/maker/id/4/

<h3 class="my-subject">a</h3> 

<ul class='ex'>....</ul> 
<ul class='ex'>....</ul> 
<ul class='ex'>....</ul> 
<ul class='ex'>....</ul> 
<ul class='ex'>....</ul> 
<ul class='ex'>....</ul> 

<h3 class="my-subject">b</h3> 

<ul class='ex'>....</ul> 
<ul class='ex'>....</ul> 
<ul class='ex'>....</ul> 
<ul class='ex'>....</ul> 
<ul class='ex'>....</ul> 
<ul class='ex'>....</ul> 

我怎样才能得到公正的ul.ex通过<h3 class="my-subject">a</h3>

6个兄弟姐妹，并通过<h3 class="my-subject">b</h3>得到下一个6 ul？

Answer 1

由于<ul>标签的数量可能有所不同，因此可以采用几种方法。

使用XPath：

var h3Xpath = "//h3[@class='my-subject']"; 
var query = doc.DocumentNode.SelectNodes(h3Xpath); 
foreach (var h3 in query) 
{ 
    var value = h3.InnerText; 
    var ulXpathFmt = "following-sibling::ul[@class='ex' and " + 
     "preceding-sibling::h3[@class='my-subject'][1]='{0}']"; 
    var uls = h3.SelectNodes(String.Format(ulXpathFmt, value)); 
    // do something with the uls 
} 

我一般不会使用XPath，但单独使用LINQ的一些以及混合做这一切。

var h3Xpath = "//h3[@class='my-subject']"; 
var query = doc.DocumentNode.SelectNodes(h3Xpath); 
foreach (var h3 in query) 
{ 
    var ulXpath = "following-sibling::*"; 
    var uls = h3.SelectNodes(ulXpath) 
     .TakeWhile(tag => tag.Name == "ul" && 
          tag.Attributes["class"].Value == "ex"); 
    // do something with the uls 
}