问一linq to xml 问题

Question

我的xml如下：<?xml version='1.0' encoding='UTF-8'?><?xml-stylesheet href="http://www.blogger.com/styles/atom.css" type="text/css"?><feed xmlns='http://www.w3.org/2005/Atom' xmlns:openSearch='http://a9.com/-/spec/opensearchrss/1.0/'><id>tag:blogger.com,1999:user-50665551771.blogs</id><updated>2010-10-31T10:20:48.620Z</updated><title type='text'>XXXX's Blogs</title><link rel='http://schemas.google.com/g/2005#feed' type='application/atom+xml' href='http://www.blogger.com/feeds/78578689618554454552/blogs'/><link rel='self' type='application/atom+xml' href='http://www.blogger.com/feeds/78578689618554454552/blogs'/><link rel='alternate' type='text/html' href='http://www.blogger.com/profile/78578689618554454552'/><author><name>XXXX</name><uri>http://www.blogger.com/profile/78578689618554454552</uri><email>[email protected]</email></author><generator version='7.00' uri='http://www.blogger.com'>Blogger</generator><openSearch:totalResults>1</openSearch:totalResults><openSearch:startIndex>1</openSearch:startIndex><openSearch:itemsPerPage>25</openSearch:itemsPerPage><entry><id>tag:blogger.com,1999:user-50665551771.blog-6589794563979856415</id><published>2010-01-29T12:05:59.905-08:00</published><updated>2010-10-31T03:06:35.061-07:00</updated><title type='text'>XXXX博客</title><summary type='html'></summary><link rel='self' type='application/atom+xml' href='http://www.blogger.com/feeds/78578689618554454552/blogs/6589794563979856415'/><link rel='alternate' type='text/html' href='http://xxxxcom.blogspot.com/'/><link rel='http://schemas.google.com/g/2005#feed' type='application/atom+xml' href='http://xxxxcom.blogspot.com/feeds/posts/default'/><link rel='http://schemas.google.com/g/2005#post' type='application/atom+xml' href='http://www.blogger.com/feeds/6589794563979856415/posts/default'/><link rel='http://schemas.google.com/blogger/2008#template' type='application/atom+xml' href='http://www.blogger.com/feeds/6589794563979856415/template'/><link rel='http://schemas.google.com/blogger/2008#settings' type='application/atom+xml' href='http://www.blogger.com/feeds/6589794563979856415/settings'/><author><name>XXXX</name><uri>http://www.blogger.com/profile/78578689618554454552</uri><email>[email protected]</email></author></entry></feed>
我想取出<link rel='alternate' type='text/html' href='http://xxxxcom.blogspot.com/'/>里的href值即：http://xxxxcom.blogspot.com/我的linq:XNamespace ad = "http://www.w3.org/2005/Atom";
        var vxml3 = from sturl3 in root.Descendants(ad + "link")
                     where (string)sturl3.Attribute("rel") == @"alternate"
                     select sturl3;这样取出的符合rel="alternate"有两条数据，我如何取得到第二条数据？

Answer 1

  var vxml3 = (from sturl3 in root.Descendants(ad + "link")
                        where (string)sturl3.Attribute("rel") == @"alternate"
                        select sturl3).LastOrDefault();

Answer 2

var vxml3 = (from sturl3 in root.Descendants(ad + "link")
                        where (string)sturl3.Attribute("rel") == @"alternate"
                        select sturl3.Attribute("href").Value).LastOrDefault();
            if (vxml3 != null)
            {
                Console.WriteLine(vxml3);
            }

Answer 3

XNamespace ad = "http://www.w3.org/2005/Atom";
var Query1 = root.Element(ad+"entry")
                 .Descendants(ad + "link")
                 .FirstOrDefault(l => l.Attribute("rel").Value == @"alternate");