var doc = new XDocument(
    new XDeclaration("1.0", "utf-8", "yes"),
    new XElement("Books",
        new XElement("Book",
            new XAttribute("Id", "1"),
            new XElement("Title", "C# in Depth"),
            new XElement("Author", "Jon Skeet")
        )
    )
);

doc.Save("books.xml");

var doc = XDocument.Load("books.xml");

// 查詢所有書(shū)名
var titles = doc.Descendants("Title")
                .Select(t => t.Value)
                .ToList();

// 查詢 Id=1 的書(shū)
var book = doc.Descendants("Book")
              .FirstOrDefault(b => b.Attribute("Id")?.Value == "1");

Console.WriteLine(book?.Element("Title")?.Value);

// 添加新書(shū)
doc.Root?.Add(
    new XElement("Book",
        new XAttribute("Id", "2"),
        new XElement("Title", "Effective C#"),
        new XElement("Author", "Bill Wagner")
    )
);

// 刪除某本書(shū)
var bookToDelete = doc.Descendants("Book")
                      .FirstOrDefault(b => b.Attribute("Id")?.Value == "1");
bookToDelete?.Remove();

doc.Save("books.xml");

var xmlDoc = new XmlDocument();
xmlDoc.Load("books.xml");

// 查找節(jié)點(diǎn)
XmlNode? bookNode = xmlDoc.SelectSingleNode("http://Book[@Id='1']");
if (bookNode != null)
{
    var title = bookNode["Title"]?.InnerText;
    Console.WriteLine(title);
}

// 添加節(jié)點(diǎn)
XmlElement newBook = xmlDoc.CreateElement("Book");
newBook.SetAttribute("Id", "3");
var titleElem = xmlDoc.CreateElement("Title");
titleElem.InnerText = "Pro C#";
newBook.AppendChild(titleElem);
xmlDoc.DocumentElement?.AppendChild(newBook);

xmlDoc.Save("books.xml");

using var reader = XmlReader.Create("huge_file.xml");
while (reader.Read())
{
    if (reader.NodeType == XmlNodeType.Element && reader.Name == "Book")
    {
        // 只處理 Book 節(jié)點(diǎn)，不加載全文檔
        var id = reader.GetAttribute("Id");
        // 進(jìn)一步解析子元素（可配合 ReadSubtree）
    }
}

using var writer = XmlWriter.Create("output.xml", new XmlWriterSettings { Indent = true });
writer.WriteStartDocument();
writer.WriteStartElement("Books");

writer.WriteStartElement("Book");
writer.WriteAttributeString("Id", "1");
writer.WriteElementString("Title", "Clean Code");
writer.WriteEndElement(); // Book

writer.WriteEndElement(); // Books
writer.WriteEndDocument();

<book xmlns="http://example.com/books">
  <title>C# Guide</title>
</book>

XNamespace ns = "http://example.com/books";
var title = doc.Descendants(ns + "title").First().Value;

doc.Save(new StreamWriter("file.xml", false, Encoding.UTF8));
// 或使用 XDocument + SaveOptions

var settings = new XmlReaderSettings
{
    DtdProcessing = DtdProcessing.Prohibit,
    XmlResolver = null
};
using var reader = XmlReader.Create(stream, settings);