Question

Given the following XML file :

<a m="1">
    <b n="1" o="2">
        <c p="3">3</c>
        <d/>
    </b>
    <b n="1" o="2">
        <c p="3">3</c>
        <d q="3">
            <e r="2">2</e>
        </d>
        <f s="1"/>
    </b>
</a>

How can I find the following expressions :

1. count(/*/*/*)  =  5
2. count (/*//*)  = 6
3. count (/*/*//@*) = 4

I ran the xml file with those xpath expressions in Java , but I don’t understand why the answers are 5,6,4 .

Can someone please explain how can I calculate the above expressions (not using a java code) but by understanding the actual concept of the commands /*/*/* and /*//* and /*/*//@* ?

Much appreciated

Answer 1

/*/*/*

This selects all “grand-children of the top element — these are: c, d, c, d

/*//*

This selects all descendant elements of the top element: b, c, d, b, c, d, e, f

/*/*//@*

This selects all attributes either of children of the top element or of their descendants: n, o, p, n, o, p, q, r, s.

Therefore, the counts produced must be, respectively:

4, 8, 9

XSLT – based verification:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output method="text"/>

 <xsl:template match="/">
   <xsl:value-of select="count(/*/*/*)"/>
=========
   <xsl:value-of select="count(/*//*)"/>
=========
   <xsl:value-of select="count(/*/*//@*)"/>
 </xsl:template>
</xsl:stylesheet>

When this transformation is performed on the provided XML document (never, never ever present the document with a picture!!!):

<a m="1">
 <b n="1" o="2">
   <c p="3">3</c>
   <d/>
 </b>
 <b n="1" o="2">
   <c p="3">3</c>
   <d q="3">
     <e r="2">2</e>
   </d>
 </b>
 <f s="1"/>
</a>

The Xpath expressions are evaluated and their results are copied to the output:

   4
=========
   8
=========
   9