39 lines
3.8 KiB
HTML
39 lines
3.8 KiB
HTML
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Retrieving Attributes</title><meta name="generator" content="DocBook XSL Stylesheets V1.61.2"><link rel="home" href="index.html" title="Libxml Tutorial"><link rel="up" href="index.html" title="Libxml Tutorial"><link rel="previous" href="ar01s07.html" title="Writing Attribute"><link rel="next" href="ar01s09.html" title="Encoding Conversion"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Retrieving Attributes</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s07.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s09.html">Next</a></td></tr></table><hr></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="xmltutorialattribute"></a>Retrieving Attributes</h2></div></div><div></div></div><p><a class="indexterm" name="id2587236"></a>
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Retrieving the value of an attribute is similar to the previous
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example in which we retrieved a node's text contents. In this case we'll
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extract the value of the <span class="acronym">URI</span> we added in the previous
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section. Full code: <a href="apg.html" title="G. Code for Retrieving Attribute Value Example">Appendix G, <i>Code for Retrieving Attribute Value Example</i></a>.</p><p>
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The initial steps for this example are similar to the previous ones: parse
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the doc, find the element you are interested in, then enter a function to
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carry out the specific task required. In this case, we call
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<tt class="function">getReference</tt>:
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</p><pre class="programlisting">
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void
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getReference (xmlDocPtr doc, xmlNodePtr cur) {
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xmlChar *uri;
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cur = cur->xmlChildrenNode;
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while (cur != NULL) {
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if ((!xmlStrcmp(cur->name, (const xmlChar *)"reference"))) {
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<a name="getattributevalue"></a><img src="images/callouts/1.png" alt="1" border="0"> uri = xmlGetProp(cur, "uri");
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printf("uri: %s\n", uri);
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xmlFree(uri);
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}
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cur = cur->next;
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}
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return;
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}
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</pre><p>
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</p><div class="calloutlist"><table border="0" summary="Callout list"><tr><td width="5%" valign="top" align="left"><a href="#getattributevalue"><img src="images/callouts/1.png" alt="1" border="0"></a> </td><td valign="top" align="left"><p>
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The key function is <tt class="function"><a href="https://gnome.pages.gitlab.gnome.org/libxml2/devhelp/libxml2-tree.html#XMLGETPROP" target="_top">xmlGetProp</a></tt>, which returns an
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<tt class="varname">xmlChar</tt> containing the attribute's value. In this case,
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we just print it out.
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</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td colspan="2" align="left" valign="top"><p>
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If you are using a <span class="acronym">DTD</span> that declares a fixed or
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default value for the attribute, this function will retrieve it.
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</p></td></tr></table></div><p>
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</p></td></tr></table></div><p>
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</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ar01s07.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="index.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ar01s09.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Writing Attribute </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Encoding Conversion</td></tr></table></div></body></html>
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