Strange behaviour of AppendChild

[Sek]

Hi Folks,

I have come across a behaviour which seems strange to me.

I wrote the following code for a task:

-----BEGIN CODE-------
XmlDocument idc = new XmlDocument();
idc.LoadXml("<book><title>The Confidence
Man</title><first-name>Herman</first-name><last-name>Melville</last-name></book>");

XmlNode nd = idc.SelectSingleNode("/book");
XmlNode krs = idc.CreateElement("hello");

foreach (XmlNode cl in nd.ChildNodes)
{
Console.WriteLine(cl.Name + " : " + cl.InnerText);
krs.AppendChild(cl);
}

foreach (XmlNode ct in krs.ChildNodes)
{
Console.WriteLine(ct.Name + " : " + ct.InnerText);
}

Console.ReadLine();
return;

-----END CODE-----

I expected the code to copy the child nodes of "book" node to the
"hello" node.
Instead, only the first child of "book" was appended to "hello" node
bcoz, the foreach loop quits after first iteration.

Am i missing anything?

TIA
Sek.

[Martin Honnen]

Sek wrote:

XmlDocument idc = new XmlDocument();
idc.LoadXml("<book><title>The Confidence
Man</title><first-name>Herman</first-name><last-name>Melville</last-name></book>");

XmlNode nd = idc.SelectSingleNode("/book");
XmlNode krs = idc.CreateElement("hello");

foreach (XmlNode cl in nd.ChildNodes)
{
Console.WriteLine(cl.Name + " : " + cl.InnerText);
krs.AppendChild(cl);
}

I expected the code to copy the child nodes of "book" node to the
"hello" node.
Instead, only the first child of "book" was appended to "hello" node
bcoz, the foreach loop quits after first iteration.

Using foreach over a collection that changes while you want to enumerate
is not a good idea and does not give reliable results. And the
ChildNodes collection of nd changes when you move a child cl to the krs
element with krs.AppendChild.

You can use an approach alike
while (nd.HasChildNodes) {
krs.AppendChild(nd.FirstChild);
}
--

Martin Honnen --- MVP XML
http://JavaScript.FAQTs.com/