Linq to XML 后代和元素有什么区别 [英] What is the difference between Linq to XML Descendants and Elements

问题描述

我在 VS IntelliSense 中遇到过这两个关键字.我试图用谷歌搜索它们之间的区别，但没有得到明确的答案.其中哪一个对中小型 XML 文件具有最佳性能.谢谢

解决方案

Elements 只找到那些直接后代的元素，即直接的孩子.

Descendants级别，即子代、孙代等...

<小时>

这是一个演示差异的示例:

代码:

XDocument doc = XDocument.Load("input.xml");XElement 根 = doc.Root;foreach (XElement e in root.Elements("bar")){Console.WriteLine("元素:" + e.Value);}foreach (XElement e in root.Descendants("bar")){Console.WriteLine("后代:" + e.Value);}

结果:

<前>元素:测试 1元素:测试 3后代:测试1后代:测试2后代:测试3

如果您知道您想要的元素是直接子元素，那么如果您使用 Elements 而不是 Descendants，您将获得更好的性能.

I have came across both these keywords in the VS IntelliSense. I tried to googling the difference between them and did not get a clear answer. Which one of these have the best performance with small to medium XML files. Thanks

解决方案

Elements finds only those elements that are direct descendents, i.e. immediate children.

Descendants finds children at any level, i.e. children, grand-children, etc...

---

Here is an example demonstrating the difference:

<?xml version="1.0" encoding="utf-8" ?>
<foo>
    <bar>Test 1</bar>
    <baz>
        <bar>Test 2</bar>
    </baz>
    <bar>Test 3</bar>
</foo>

Code:

XDocument doc = XDocument.Load("input.xml");
XElement root = doc.Root;

foreach (XElement e in root.Elements("bar"))
{
    Console.WriteLine("Elements : " + e.Value);
}

foreach (XElement e in root.Descendants("bar"))
{
    Console.WriteLine("Descendants : " + e.Value);
}

Result:

Elements : Test 1
Elements : Test 3
Descendants : Test 1
Descendants : Test 2
Descendants : Test 3

If you know that the elements you want are immediate children then you will get better performance if you use Elements instead of Descendants.

这篇关于Linq to XML 后代和元素有什么区别的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！