SelectSingleNode() with XPath C# Failure

Question

i got a XML File as export from Wireshark and want to select the Number of the actual frame

The structure of this file is like this

<packet>
    <proto>
        ...
    </proto>
    ....
    <proto>
        <field name="frame.number" show="1">
    </proto>
</packet>
<packet>
    <proto>
        ...
    </proto>
    ....
    <proto>
        <field name="frame.number" show="2">
    </proto>
</packet>

...and so on...

I use this code to select the packets/fields

XmlNodeList packages = xmlDoc.SelectNodes("//packet");
foreach (XmlNode packet in packages) {
    string frameNumber = packet.SelectSingleNode("//field[@name='frame.number']").
        Attributes["show"].Value;
    Console.WriteLine(frameNumber);
}

If I Debug through the code, it always selects the right Nodes with the correct attributes. But at each iteration there is a "1" printed out.

Does anyone suspect what failure this is? I didn't found anything on the internet for this failure

Thank you very much!!

Jamiec · Accepted Answer · 2011-10-20 14:54:23Z

2

Its because your XPath in SelectSingleNode starts with // - which means "start from the root of the document". Therefore you're always getting the first one.

Just change the XPath in that method to proto/field[@name='frame.number'].

answered Oct 20, 2011 at 14:54

Jamiec

136k15 gold badges143 silver badges202 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Benni Over a year ago

Thank you! I thougt starting with // means: "start from the actual node downwards. Now I know, that I was wrong ;)

Collectives™ on Stack Overflow

SelectSingleNode() with XPath C# Failure

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related