test.xml文件

<?xml version="1.0" encoding="utf-8" ?>
- <people>
- <person tag="a">
<id>1</id>
<name>user1</name>
<age>1</age>
</person>
- <person tag="a">
<id>2</id>
<name>user2</name>
<age>2</age>
</person>
- <person tag="b">
<id>3</id>
<name>user3</name>
<age>2</age>
</person>
</people>

#region //向xml文件添加新节点有属性类型的
XElement doc = XElement.Load(@"test1.xml");

XElement root =
new XElement("person",
new XElement("id", "4"),
new XElement("name", "user4"),
new XElement("age", "4")
);

root.SetAttributeValue("tag", "c");

doc.Add(root);
doc.Save(@"test1.xml");
#endregion