XPATH to count the occurrence of child nodes in ancestor

Question

I need to count the occurrence of the child <title> nodes in the <foreword><?> element. My problem is the parent nodes of the <title> element have different names, but they all have <title> elements.

I tried using count(*) but this didn't work, it comes back "0". And if I use count(/doc/front/foreword/*/title) it comes back with '16'. How do I count the occurrence of the <title> elements inside the <foreword><?> element?

    <doc>
    <front>
    <lep></lep>
    <verstat></verstat>
    <contents></contents>
    <illuslist></illuslist>
    <tablelist></tablelist>
    <foreword>
    <para0><title>para0</title></para0>
    <applicdef><title>applicdef</title></applicdef>
    <applicdef><title>applicdef</title></applicdef>
    <applicdef><title>applicdef</title></applicdef>
    <applicdef><title>applicdef</title></applicdef>
    <applicdef><title>applicdef</title></applicdef>
    <para0><title>para0</title></para0>
    <para0><title>para0</title></para0>
    <para0><title>para0</title></para0>
    <para0><title>para0</title></para0>
    </foreword>
    </front>
    </doc>

I numbered the title elements with the number that should be displayed (1.0 purpose, 2. applic...etc.

so the output would be like

    <para0><title>1. para0</title></para0>
    <applicdef><title>2.applicdef</title></applicdef>
    <applicdef><title>3.applicdef</title></applicdef>
    <applicdef><title>4.applicdef</title></applicdef>
    <applicdef><title>5.applicdef</title></applicdef>
    <applicdef><title>6.applicdef</title></applicdef>

Answer 1

Let's use your real life scenario, i.e. XSLT. Here is a solution by using identity transform.

Input XML

<?xml version="1.0"?>
<doc>
    <front>
        <lep></lep>
        <verstat></verstat>
        <contents></contents>
        <illuslist></illuslist>
        <tablelist></tablelist>
        <foreword>
            <para0>
                <title>para0</title>
            </para0>
            <applicdef>
                <title>applicdef</title>
            </applicdef>
            <applicdef>
                <title>applicdef</title>
            </applicdef>
            <applicdef>
                <title>applicdef</title>
            </applicdef>
            <applicdef>
                <title>applicdef</title>
            </applicdef>
            <applicdef>
                <title>applicdef</title>
            </applicdef>
            <para0>
                <title>para0</title>
            </para0>
            <para0>
                <title>para0</title>
            </para0>
            <para0>
                <title>para0</title>
            </para0>
            <para0>
                <title>para0</title>
            </para0>
        </foreword>
    </front>
</doc>

XSLT

<?xml version="1.0"?>
<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:strip-space elements="*"/>

    <xsl:template match="@*|node()">
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:copy>
    </xsl:template>

    <xsl:template match="title">
        <title>
            <xsl:value-of select="concat(count(../preceding-sibling::*)+1,'. ', .)"/>
        </title>
    </xsl:template>
</xsl:stylesheet>

Output

<doc>
  <front>
    <lep/>
    <verstat/>
    <contents/>
    <illuslist/>
    <tablelist/>
    <foreword>
      <para0>
        <title>1. para0</title>
      </para0>
      <applicdef>
        <title>2. applicdef</title>
      </applicdef>
      <applicdef>
        <title>3. applicdef</title>
      </applicdef>
      <applicdef>
        <title>4. applicdef</title>
      </applicdef>
      <applicdef>
        <title>5. applicdef</title>
      </applicdef>
      <applicdef>
        <title>6. applicdef</title>
      </applicdef>
      <para0>
        <title>7. para0</title>
      </para0>
      <para0>
        <title>8. para0</title>
      </para0>
      <para0>
        <title>9. para0</title>
      </para0>
      <para0>
        <title>10. para0</title>
      </para0>
    </foreword>
  </front>
</doc>