Question about System.Xml.XmlDocument.SelectNodes

[Michael H]

Hello group,
I have a some xml that looks like this below:

<tuneRequests ct="3" xmlns:sql="urn:schemas-microsoft-com:xml-sql"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

<tr xsi:type="trGenericType" number="2">

<s name="KATU" call_sign="KATU" affiliation="ABC Affiliate"
id="28455700" ppv="0" />

</tr>

<tr xsi:type="trGenericType" number="3">

<s name="KOAB" call_sign="KOAB" affiliation="PBS Affiliate"
id="28460723" ppv="0" />

</tr>

<tr xsi:type="trGenericType" number="6">

<s name="KOIN" call_sign="KOIN" affiliation="CBS Affiliate"
id="28455365" ppv="0" />

</tr>

</tuneRequests>

If I use code as this to populate an array with the value from the
<tr> element:

// doc is an instance of XmlDocument

foreach (node in doc.SelectNodes(@"tuneRequests/tr") ) )
....
then use this code to populate a different array

foreach (node in doc.SelectNodes(@"tuneRequests/tr/s") ) )
....
Is it guaranteed that nodes will be returned in the same order,
top-to-bottom as they appear in the xml document for both
SelectNodes() usages?

I'd like to use this simple code to match the channel number in an
<tr> with the name, call_sign, and affiliation attributes of the
nested <s> element with these two simple foreach structures.

Thanks for any help,
Michael Hughes - Silverton, Oregon
http://wou.ath.cx/Trivia
http://wou.ath.cx/AmateurRadio

[Martin Honnen]

Michael H wrote:

If I use code as this to populate an array with the value from the
<tr> element:

// doc is an instance of XmlDocument

foreach (node in doc.SelectNodes(@"tuneRequests/tr") ) )
...
then use this code to populate a different array

foreach (node in doc.SelectNodes(@"tuneRequests/tr/s") ) )
...
Is it guaranteed that nodes will be returned in the same order,
top-to-bottom as they appear in the xml document for both
SelectNodes() usages?

Yes, you get the nodes in document order.
But it could be more efficient to use
foreach (node in doc.SelectNodes(@"tuneRequests/tr")) {
foreach (node2 in node.SelectNodes(@"s"))
that way you avoid that the XPath implementation has to do the same work
of finding tuneRequests/tr twice.

--

Martin Honnen
http://JavaScript.FAQTs.com/

[Michael H]

On Sat, 05 Mar 2005 12:48:33 +0100, Martin Honnen <ma*******@yahoo.de>
wrote:

Michael H wrote:

If I use code as this to populate an array with the value from the
<tr> element:

// doc is an instance of XmlDocument

foreach (node in doc.SelectNodes(@"tuneRequests/tr") ) )
...
then use this code to populate a different array

foreach (node in doc.SelectNodes(@"tuneRequests/tr/s") ) )
...
Is it guaranteed that nodes will be returned in the same order,
top-to-bottom as they appear in the xml document for both
SelectNodes() usages?

Yes, you get the nodes in document order.
But it could be more efficient to use
foreach (node in doc.SelectNodes(@"tuneRequests/tr")) {
foreach (node2 in node.SelectNodes(@"s"))
that way you avoid that the XPath implementation has to do the same work
of finding tuneRequests/tr twice.

Thanks a lot Martin,

I don't have a lot of experience w/ xpath and xml as of yet. Your
suggestion looks a lot better than the way I had planned.

Auf wedersehen,
Michael Hughes - Silverton, Oregon
http://wou.ath.cx/Trivia
http://wou.ath.cx/AmateurRadio