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XContainer.AddFirst Method (Object[])

Adds the specified content as the first children of this document or element.

Namespace:  System.Xml.Linq
Assembly:  System.Xml.Linq (in System.Xml.Linq.dll)

public void AddFirst(
	params Object[] content
)

Parameters

content
Type: System.Object[]
A parameter list of content objects.

ExceptionCondition
InvalidOperationException

The parent is null.

This method adds the new content before the existing content of the XContainer.

For details about the valid content that can be passed to this function, see Valid Content of XElement and XDocument Objects.

This method will raise the Changed and the Changing events.

The following example creates two XML trees, and uses this method to add an XElement object as the first element to one of them. It also adds the results of a LINQ query to the XML tree.

XElement srcTree = new XElement("Root",
    new XElement("Element1", 1),
    new XElement("Element2", 2),
    new XElement("Element3", 3),
    new XElement("Element4", 4),
    new XElement("Element5", 5)
);
XElement xmlTree = new XElement("Root",
    new XElement("Child1", 1),
    new XElement("Child2", 2),
    new XElement("Child3", 3),
    new XElement("Child4", 4),
    new XElement("Child5", 5)
);
xmlTree.AddFirst(new XElement("NewChild", "new content"));
xmlTree.AddFirst(
    from el in srcTree.Elements()
    where (int)el > 3
    select el
);
// Even though Child9 does not exist in srcTree, the following statement will not
// throw an exception, and nothing will be added to xmlTree.
xmlTree.AddFirst(srcTree.Element("Child9"));
Console.WriteLine(xmlTree);

This example produces the following output:

<Root>
  <Element4>4</Element4>
  <Element5>5</Element5>
  <NewChild>new content</NewChild>
  <Child1>1</Child1>
  <Child2>2</Child2>
  <Child3>3</Child3>
  <Child4>4</Child4>
  <Child5>5</Child5>
</Root>

.NET Framework

Supported in: 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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