Find position of a node using XPath

Anyone know how to get the position of a node using XPath?

Say I have the following xml:

<a>
    <b>zyx</b>
    <b>wvu</b>
    <b>tsr</b>
    <b>qpo</b>
</a>

I can use the following xpath query to select the third <b> node (<b>tsr</b>):

a/b[.='tsr']

Which is all well and good but I want to return the ordinal position of that node, something like:

a/b[.='tsr']/position()

(but a bit more working!)

Is it even possible?

edit: Forgot to mention am using .net 2 so it's xpath 1.0!

Update: Ended up using James Sulak's excellent answer. For those that are interested here's my implementation in C#:

int position = doc.SelectNodes("a/b[.='tsr']/preceding-sibling::b").Count + 1;

// Check the node actually exists
if (position > 1 || doc.SelectSingleNode("a/b[.='tsr']") != null)
{
    Console.WriteLine("Found at position = {0}", position);
}

Solution 1:

Try:

count(a/b[.='tsr']/preceding-sibling::*)+1.

Solution 2:

You can do this with XSLT but I'm not sure about straight XPath.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" encoding="utf-8" indent="yes" 
              omit-xml-declaration="yes"/>
  <xsl:template match="a/*[text()='tsr']">
    <xsl:number value-of="position()"/>
  </xsl:template>
  <xsl:template match="text()"/>
</xsl:stylesheet>

Solution 3:

I realize that the post is ancient.. but..

replace'ing the asterisk with the nodename would give you better results

count(a/b[.='tsr']/preceding::a)+1.

instead of

count(a/b[.='tsr']/preceding::*)+1.

Solution 4:

If you ever upgrade to XPath 2.0, note that it provides function index-of, it solves problem this way:

index-of(//b, //b[.='tsr'])

Where:

• 1st parameter is sequence for searching
• 2nd is what to search