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<h1>XPath Syntax</h1>
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<p class="intro">XPath uses path expressions to select nodes or node-sets in an XML document.
The node is selected by following a path or steps.</p>
<hr />
<h2>The XML Example Document</h2>
<p>We will use the following XML document in the examples below.</p>
<table width="100%" border="1" class="ex" cellspacing="0" id="table33">
<tr>
<td>
<pre><?xml version="1.0" encoding="ISO-8859-1"?></pre>
<pre><bookstore></pre>
<pre><book>
<title lang="eng">Harry Potter</title>
<price>29.99</price>
</book></pre>
<pre><book>
<title lang="eng">Learning XML</title>
<price>39.95</price>
</book></pre>
<pre></bookstore>
</pre>
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<hr />
<h2>Selecting Nodes</h2>
<p>XPath uses path expressions to select nodes in an XML document. The node is selected by following a path or steps.
The most useful
path expressions are listed below:</p>
<table class="ex" cellspacing="0" border="1" width="100%" id="table1">
<tr>
<td width="20%" valign="top"><b>Expression</b></td>
<td valign="top"><b>Description</b></td>
</tr>
<tr>
<td valign="top"><i>nodename</i></td>
<td valign="top">Selects all child nodes of the named node</td>
</tr>
<tr>
<td valign="top">/</td>
<td valign="top">Selects from the root node</td>
</tr>
<tr>
<td valign="top">//</td>
<td valign="top">Selects nodes in the document from the current node that
match the selection no matter where they are </td>
</tr>
<tr>
<td valign="top">.</td>
<td valign="top">Selects the current node</td>
</tr>
<tr>
<td valign="top">..</td>
<td valign="top">Selects the parent of the current node</td>
</tr>
<tr>
<td valign="top">@</td>
<td valign="top">Selects attributes</td>
</tr>
</table>
<h3>Examples</h3>
<p>In the table below we have listed some path expressions and the result of the
expressions:</p>
<table class="ex" cellspacing="0" border="1" width="100%" id="table34">
<tr>
<td width="30%" valign="top"><b>Path Expression</b></td>
<td valign="top"><b>Result</b></td>
</tr>
<tr>
<td valign="top">bookstore</td>
<td valign="top">Selects all the child nodes of the bookstore element</td>
</tr>
<tr>
<td valign="top">/bookstore</td>
<td valign="top">Selects the root element bookstore<p><b>Note:</b> If the path starts with a slash ( / ) it
always represents an absolute
path to an element!</p></td>
</tr>
<tr>
<td valign="top">bookstore/book</td>
<td valign="top">Selects all book elements that are children of bookstore</td>
</tr>
<tr>
<td valign="top">//book</td>
<td valign="top">Selects all book elements no matter where they are in the
document</td>
</tr>
<tr>
<td valign="top">bookstore//book</td>
<td valign="top">Selects all book elements that are descendant of the
bookstore element, no matter where they are under the bookstore element</td>
</tr>
<tr>
<td valign="top">//@lang</td>
<td valign="top">Selects all attributes that are named lang</td>
</tr>
</table>
<br />
<hr />
<h2>Predicates</h2>
<p>Predicates are used to find a specific node or a node that contains a specific value.</p>
<p>Predicates are always embedded in square brackets.</p>
<h3>Examples</h3>
<p>In the table below we have listed some path expressions with predicates and the result of the
expressions:</p>
<table class="ex" cellspacing="0" border="1" width="100%" id="table35">
<tr>
<td width="50%" valign="top"><b>Path Expression</b></td>
<td valign="top"><b>Result</b></td>
</tr>
<tr>
<td valign="top">/bookstore/book[1] </td>
<td valign="top">Selects the first book element that is the child of the
bookstore element.<p><b>Note:</b> IE5 and later has implemented that [0] should be the first node,
but according to the W3C standard it should have been [1]!!</p></td>
</tr>
<tr>
<td valign="top">/bookstore/book[last()]</td>
<td valign="top">Selects the last book element that is the child of the
bookstore element</td>
</tr>
<tr>
<td valign="top">/bookstore/book[last()-1]</td>
<td valign="top">Selects the last but one book element that is the child of the
bookstore element</td>
</tr>
<tr>
<td valign="top">/bookstore/book[position()<3]</td>
<td valign="top">Selects the first two book elements that are children of the
bookstore element</td>
</tr>
<tr>
<td valign="top">//title[@lang]</td>
<td valign="top">Selects all the title elements that have an attribute named
lang</td>
</tr>
<tr>
<td valign="top">//title[@lang='eng']</td>
<td valign="top">Selects all the title elements that have an attribute named lang
with a value of 'eng'</td>
</tr>
<tr>
<td valign="top">/bookstore/book[price>35.00]</td>
<td valign="top">Selects all the book elements of the bookstore element that
have a price element with a value greater than 35.00</td>
</tr>
<tr>
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