mirror of
https://gitlab.gnome.org/GNOME/libxml2.git
synced 2024-12-27 03:21:26 +03:00
doc/tutorial/xmltutorial.xml, xmltutorial.pdf, *.html fix Xpath memory
Tue Aug 24 20:49:15 MDT 2004 John Fleck <jfleck@inkstain.net> * doc/tutorial/xmltutorial.xml, xmltutorial.pdf, *.html fix Xpath memory leak (thanks to sKaBoy and William Brack)
This commit is contained in:
MDT 2004 John Fleck
John Fleck
parent
abbf9dfd62
commit
4c3bb7d8a2
@ -1,3 +1,8 @@
|
||||
Tue Aug 24 20:49:15 MDT 2004 John Fleck <jfleck@inkstain.net>
|
||||
|
||||
* doc/tutorial/xmltutorial.xml, xmltutorial.pdf, *.html
|
||||
fix Xpath memory leak (thanks to sKaBoy and William Brack)
|
||||
|
||||
Tue Aug 24 21:10:59 CEST 2004 Igor Zlatkovic <igor@zlatkovic.com>
|
||||
|
||||
* parser.c: fixed path problem in DTD loading reported by
|
||||
|
||||
@ -1,4 +1,4 @@
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>A. Compilation</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="ar01s09.html" title="Encoding Conversion"><link rel="next" href="apb.html" title="B. Sample Document"></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">A. Compilation</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s09.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="apb.html">Next</a></td></tr></table><hr></div><div class="appendix" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="compilation"></a>A. Compilation</h2></div></div><div></div></div><p><a class="indexterm" name="id2902089"></a>
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>A. Compilation</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="ar01s09.html" title="Encoding Conversion"><link rel="next" href="apb.html" title="B. Sample Document"></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">A. Compilation</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s09.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="apb.html">Next</a></td></tr></table><hr></div><div class="appendix" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="compilation"></a>A. Compilation</h2></div></div><div></div></div><p><a class="indexterm" name="id2587670"></a>
|
||||
<span class="application">Libxml</span> includes a script,
|
||||
<span class="application">xml2-config</span>, that can be used to generate
|
||||
flags for compilation and linking of programs written with the
|
||||
|
||||
@ -23,12 +23,21 @@ getnodeset (xmlDocPtr doc, xmlChar *xpath){
|
||||
xmlXPathObjectPtr result;
|
||||
|
||||
context = xmlXPathNewContext(doc);
|
||||
if (context == NULL) {
|
||||
printf("Error in xmlXPathNewContext\n");
|
||||
return NULL;
|
||||
}
|
||||
result = xmlXPathEvalExpression(xpath, context);
|
||||
xmlXPathFreeContext(context);
|
||||
if (result == NULL) {
|
||||
printf("Error in xmlXPathEvalExpression\n");
|
||||
return NULL;
|
||||
}
|
||||
if(xmlXPathNodeSetIsEmpty(result->nodesetval)){
|
||||
xmlXPathFreeObject(result);
|
||||
printf("No result\n");
|
||||
return NULL;
|
||||
}
|
||||
xmlXPathFreeContext(context);
|
||||
return result;
|
||||
}
|
||||
int
|
||||
@ -63,6 +72,5 @@ main(int argc, char **argv) {
|
||||
xmlCleanupParser();
|
||||
return (1);
|
||||
}
|
||||
|
||||
</pre><p>
|
||||
</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="apc.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="ape.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">C. Code for Keyword Example </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> E. Code for Add Keyword Example</td></tr></table></div></body></html>
|
||||
|
||||
@ -1,4 +1,4 @@
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>I. Acknowledgements</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="aph.html" title="H. Code for Encoding Conversion Example"><link rel="next" href="ix01.html" title="Index"></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">I. Acknowledgements</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="aph.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ix01.html">Next</a></td></tr></table><hr></div><div class="appendix" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2902708"></a>I. Acknowledgements</h2></div></div><div></div></div><p>A number of people have generously offered feedback, code and
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>I. Acknowledgements</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="aph.html" title="H. Code for Encoding Conversion Example"><link rel="next" href="ix01.html" title="Index"></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">I. Acknowledgements</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="aph.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ix01.html">Next</a></td></tr></table><hr></div><div class="appendix" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2588597"></a>I. Acknowledgements</h2></div></div><div></div></div><p>A number of people have generously offered feedback, code and
|
||||
suggested improvements to this tutorial. In no particular order:
|
||||
<span class="simplelist">Daniel Veillard, Marcus Labib Iskander, Christopher R. Harris, Igor Zlatkovic, Niraj Tolia, David Turover</span>
|
||||
</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="aph.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="ix01.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">H. Code for Encoding Conversion Example </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Index</td></tr></table></div></body></html>
|
||||
|
||||
@ -1,13 +1,13 @@
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Data Types</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="index.html" title="Libxml Tutorial"><link rel="next" href="ar01s03.html" title="Parsing the file"></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">Data Types</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="index.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s03.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="xmltutorialdatatypes"></a>Data Types</h2></div></div><div></div></div><p><span class="application">Libxml</span> declares a number of data types we
|
||||
will encounter repeatedly, hiding the messy stuff so you do not have to deal
|
||||
with it unless you have some specific need.</p><p>
|
||||
</p><div class="variablelist"><dl><dt><span class="term"><a class="indexterm" name="id2840608"></a>
|
||||
</p><div class="variablelist"><dl><dt><span class="term"><a class="indexterm" name="id2526186"></a>
|
||||
<a href="http://xmlsoft.org/html/libxml-tree.html#XMLCHAR" target="_top">xmlChar</a></span></dt><dd><p>A basic replacement for char, a byte in a UTF-8 encoded
|
||||
string. If your data uses another encoding, it must be converted to
|
||||
UTF-8 for use with <span class="application">libxml's</span>
|
||||
functions. More information on encoding is available on the <a href="http://www.xmlsoft.org/encoding.html" target="_top"><span class="application">libxml</span> encoding support web page</a>.</p></dd><dt><span class="term"><a class="indexterm" name="id2840654"></a>
|
||||
functions. More information on encoding is available on the <a href="http://www.xmlsoft.org/encoding.html" target="_top"><span class="application">libxml</span> encoding support web page</a>.</p></dd><dt><span class="term"><a class="indexterm" name="id2526232"></a>
|
||||
<a href="http://xmlsoft.org/html/libxml-tree.html#XMLDOC" target="_top">xmlDoc</a></span></dt><dd><p>A structure containing the tree created by a parsed doc. <a href="http://xmlsoft.org/html/libxml-tree.html#XMLDOCPTR" target="_top">xmlDocPtr</a>
|
||||
is a pointer to the structure.</p></dd><dt><span class="term"><a class="indexterm" name="id2840689"></a>
|
||||
is a pointer to the structure.</p></dd><dt><span class="term"><a class="indexterm" name="id2526266"></a>
|
||||
<a href="http://xmlsoft.org/html/libxml-tree.html#XMLNODEPTR" target="_top">xmlNodePtr</a>
|
||||
and <a href="http://xmlsoft.org/html/libxml-tree.html#XMLNODE" target="_top">xmlNode</a></span></dt><dd><p>A structure containing a single node. <a href="http://xmlsoft.org/html/libxml-tree.html#XMLNODEPTR" target="_top">xmlNodePtr</a>
|
||||
is a pointer to the structure, and is used in traversing the document tree.</p></dd></dl></div><p>
|
||||
|
||||
@ -31,7 +31,7 @@ Parsing the file requires only the name of the file and a single
|
||||
interact with individual nodes).</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#checkparseerror"><img src="images/callouts/4.png" alt="4" border="0"></a> </td><td valign="top" align="left"><p>Check to see that the document was successfully parsed. If it
|
||||
was not, <span class="application">libxml</span> will at this point
|
||||
register an error and stop.
|
||||
</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><a class="indexterm" name="id2839760"></a>
|
||||
</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><a class="indexterm" name="id2525337"></a>
|
||||
One common example of an error at this point is improper
|
||||
handling of encoding. The <span class="acronym">XML</span> standard requires
|
||||
documents stored with an encoding other than UTF-8 or UTF-16 to
|
||||
@ -43,5 +43,5 @@ One common example of an error at this point is improper
|
||||
</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#getrootelement"><img src="images/callouts/5.png" alt="5" border="0"></a> </td><td valign="top" align="left"><p>Retrieve the document's root element.</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#checkemptyerror"><img src="images/callouts/6.png" alt="6" border="0"></a> </td><td valign="top" align="left"><p>Check to make sure the document actually contains something.</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#checkroottype"><img src="images/callouts/7.png" alt="7" border="0"></a> </td><td valign="top" align="left"><p>In our case, we need to make sure the document is the right
|
||||
type. "story" is the root type of the documents used in this
|
||||
tutorial.</p></td></tr></table></div><p>
|
||||
<a class="indexterm" name="id2839838"></a>
|
||||
<a class="indexterm" name="id2525415"></a>
|
||||
</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ar01s02.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="ar01s04.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Data Types </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Retrieving Element Content</td></tr></table></div></body></html>
|
||||
|
||||
@ -1,4 +1,4 @@
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Retrieving Element Content</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="ar01s03.html" title="Parsing the file"><link rel="next" href="ar01s05.html" title="Using XPath to Retrieve Element Content"></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 Element Content</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s03.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s05.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="xmltutorialgettext"></a>Retrieving Element Content</h2></div></div><div></div></div><p><a class="indexterm" name="id2839861"></a>
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Retrieving Element Content</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="ar01s03.html" title="Parsing the file"><link rel="next" href="ar01s05.html" title="Using XPath to Retrieve Element Content"></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 Element Content</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s03.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s05.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="xmltutorialgettext"></a>Retrieving Element Content</h2></div></div><div></div></div><p><a class="indexterm" name="id2525439"></a>
|
||||
Retrieving the content of an element involves traversing the document
|
||||
tree until you find what you are looking for. In this case, we are looking
|
||||
for an element called "keyword" contained within element called "story". The
|
||||
|
||||
@ -26,13 +26,12 @@
|
||||
<a name="cocreatecontext"></a><img src="images/callouts/2.png" alt="2" border="0">context = xmlXPathNewContext(doc);
|
||||
<a name="corunxpath"></a><img src="images/callouts/3.png" alt="3" border="0">result = xmlXPathEvalExpression(xpath, context);
|
||||
<a name="cocheckxpathresult"></a><img src="images/callouts/4.png" alt="4" border="0">if(xmlXPathNodeSetIsEmpty(result->nodesetval)){
|
||||
xmlXPathFreeObject(result);
|
||||
printf("No result\n");
|
||||
return NULL;
|
||||
}
|
||||
xmlXPathFreeContext(context);
|
||||
return result;
|
||||
return NULL;
|
||||
</pre><p>
|
||||
</p><div class="calloutlist"><table border="0" summary="Callout list"><tr><td width="5%" valign="top" align="left"><a href="#cocontext"><img src="images/callouts/1.png" alt="1" border="0"></a> </td><td valign="top" align="left"><p>First we declare our variables.</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#cocreatecontext"><img src="images/callouts/2.png" alt="2" border="0"></a> </td><td valign="top" align="left"><p>Initialize the <tt class="varname">context</tt> variable.</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#corunxpath"><img src="images/callouts/3.png" alt="3" border="0"></a> </td><td valign="top" align="left"><p>Apply the <span class="application">XPath</span> expression.</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#cocheckxpathresult"><img src="images/callouts/4.png" alt="4" border="0"></a> </td><td valign="top" align="left"><p>Check the result.</p></td></tr></table></div><p>
|
||||
</p><div class="calloutlist"><table border="0" summary="Callout list"><tr><td width="5%" valign="top" align="left"><a href="#cocontext"><img src="images/callouts/1.png" alt="1" border="0"></a> </td><td valign="top" align="left"><p>First we declare our variables.</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#cocreatecontext"><img src="images/callouts/2.png" alt="2" border="0"></a> </td><td valign="top" align="left"><p>Initialize the <tt class="varname">context</tt> variable.</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#corunxpath"><img src="images/callouts/3.png" alt="3" border="0"></a> </td><td valign="top" align="left"><p>Apply the <span class="application">XPath</span> expression.</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#cocheckxpathresult"><img src="images/callouts/4.png" alt="4" border="0"></a> </td><td valign="top" align="left"><p>Check the result and free the memory allocated to
|
||||
<tt class="varname">result</tt> if no result is found.</p></td></tr></table></div><p>
|
||||
</p><p>The xmlPathObjectPtr returned by the function contains a set of nodes
|
||||
and other information needed to iterate through the set and act on the
|
||||
results. For this example, our functions returns the
|
||||
|
||||
@ -1,4 +1,4 @@
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Writing element content</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="ar01s05.html" title="Using XPath to Retrieve Element Content"><link rel="next" href="ar01s07.html" title="Writing Attribute"></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">Writing element content</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s05.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s07.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="xmltutorialwritingcontent"></a>Writing element content</h2></div></div><div></div></div><p><a class="indexterm" name="id2901386"></a>
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Writing element content</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="ar01s05.html" title="Using XPath to Retrieve Element Content"><link rel="next" href="ar01s07.html" title="Writing Attribute"></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">Writing element content</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s05.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s07.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="xmltutorialwritingcontent"></a>Writing element content</h2></div></div><div></div></div><p><a class="indexterm" name="id2586968"></a>
|
||||
Writing element content uses many of the same steps we used above
|
||||
— parsing the document and walking the tree. We parse the document,
|
||||
then traverse the tree to find the place we want to insert our element. For
|
||||
@ -21,7 +21,7 @@ parseStory (xmlDocPtr doc, xmlNodePtr cur, char *keyword) {
|
||||
current node pointer's location in the
|
||||
tree, specified by <tt class="varname">cur</tt>.</p></td></tr></table></div><p>
|
||||
</p><p>
|
||||
<a class="indexterm" name="id2901470"></a>
|
||||
<a class="indexterm" name="id2587052"></a>
|
||||
Once the node has been added, we would like to write the document to
|
||||
file. Is you want the element to have a namespace, you can add it here as
|
||||
well. In our case, the namespace is NULL.
|
||||
|
||||
@ -1,4 +1,4 @@
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Writing Attribute</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="ar01s06.html" title="Writing element content"><link rel="next" href="ar01s08.html" title="Retrieving Attributes"></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">Writing Attribute</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s06.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s08.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="xmltutorialwritingattribute"></a>Writing Attribute</h2></div></div><div></div></div><p><a class="indexterm" name="id2901512"></a>
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Writing Attribute</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="ar01s06.html" title="Writing element content"><link rel="next" href="ar01s08.html" title="Retrieving Attributes"></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">Writing Attribute</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s06.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s08.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="xmltutorialwritingattribute"></a>Writing Attribute</h2></div></div><div></div></div><p><a class="indexterm" name="id2587093"></a>
|
||||
Writing an attribute is similar to writing text to a new element. In
|
||||
this case, we'll add a reference <span class="acronym">URI</span> to our
|
||||
document. Full code:<a href="apf.html" title="F. Code for Add Attribute Example">Appendix F, <i>Code for Add Attribute Example</i></a>.</p><p>
|
||||
|
||||
@ -1,4 +1,4 @@
|
||||
<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="id2901654"></a>
|
||||
<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>
|
||||
Retrieving the value of an attribute is similar to the previous
|
||||
example in which we retrieved a node's text contents. In this case we'll
|
||||
extract the value of the <span class="acronym">URI</span> we added in the previous
|
||||
|
||||
@ -1,4 +1,4 @@
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Encoding Conversion</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="ar01s08.html" title="Retrieving Attributes"><link rel="next" href="apa.html" title="A. Compilation"></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">Encoding Conversion</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s08.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="apa.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="xmltutorialconvert"></a>Encoding Conversion</h2></div></div><div></div></div><p><a class="indexterm" name="id2901766"></a>
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Encoding Conversion</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="ar01s08.html" title="Retrieving Attributes"><link rel="next" href="apa.html" title="A. Compilation"></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">Encoding Conversion</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s08.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="apa.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="xmltutorialconvert"></a>Encoding Conversion</h2></div></div><div></div></div><p><a class="indexterm" name="id2587348"></a>
|
||||
Data encoding compatibility problems are one of the most common
|
||||
difficulties encountered by programmers new to <span class="acronym">XML</span> in
|
||||
general and <span class="application">libxml</span> in particular. Thinking
|
||||
|
||||
@ -22,12 +22,21 @@ getnodeset (xmlDocPtr doc, xmlChar *xpath){
|
||||
xmlXPathObjectPtr result;
|
||||
|
||||
context = xmlXPathNewContext(doc);
|
||||
if (context == NULL) {
|
||||
printf("Error in xmlXPathNewContext\n");
|
||||
return NULL;
|
||||
}
|
||||
result = xmlXPathEvalExpression(xpath, context);
|
||||
xmlXPathFreeContext(context);
|
||||
if (result == NULL) {
|
||||
printf("Error in xmlXPathEvalExpression\n");
|
||||
return NULL;
|
||||
}
|
||||
if(xmlXPathNodeSetIsEmpty(result->nodesetval)){
|
||||
xmlXPathFreeObject(result);
|
||||
printf("No result\n");
|
||||
return NULL;
|
||||
}
|
||||
xmlXPathFreeContext(context);
|
||||
return result;
|
||||
}
|
||||
int
|
||||
@ -62,4 +71,4 @@ main(int argc, char **argv) {
|
||||
xmlCleanupParser();
|
||||
return (1);
|
||||
}
|
||||
]]>
|
||||
]]>
|
||||
@ -1,4 +1,4 @@
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Libxml Tutorial</title><meta name="generator" content="DocBook XSL Stylesheets V1.61.2"><link rel="home" href="index.html" title="Libxml Tutorial"><link rel="next" href="ar01s02.html" title="Data Types"></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">Libxml Tutorial</th></tr><tr><td width="20%" align="left"> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s02.html">Next</a></td></tr></table><hr></div><div class="article" lang="en"><div class="titlepage"><div><div><h1 class="title"><a name="id2788097"></a>Libxml Tutorial</h1></div><div><div class="author"><h3 class="author"><span class="firstname">John</span> <span class="surname">Fleck</span></h3></div></div><div><p class="copyright">Copyright © 2002, 2003 John Fleck</p></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr><tr><td align="left">Revision 1</td><td align="left">June 4, 2002</td></tr><tr><td align="left" colspan="2">Initial draft</td></tr><tr><td align="left">Revision 2</td><td align="left">June 12, 2002</td></tr><tr><td align="left" colspan="2">retrieving attribute value added</td></tr><tr><td align="left">Revision 3</td><td align="left">Aug. 31, 2002</td></tr><tr><td align="left" colspan="2">freeing memory fix</td></tr><tr><td align="left">Revision 4</td><td align="left">Nov. 10, 2002</td></tr><tr><td align="left" colspan="2">encoding discussion added</td></tr><tr><td align="left">Revision 5</td><td align="left">Dec. 15, 2002</td></tr><tr><td align="left" colspan="2">more memory freeing changes</td></tr><tr><td align="left">Revision 6</td><td align="left">Jan. 26. 2003</td></tr><tr><td align="left" colspan="2">add index</td></tr><tr><td align="left">Revision 7</td><td align="left">April 25, 2003</td></tr><tr><td align="left" colspan="2">add compilation appendix</td></tr><tr><td align="left">Revision 8</td><td align="left">July 24, 2003</td></tr><tr><td align="left" colspan="2">add XPath example</td></tr><tr><td align="left">Revision 9</td><td align="left">Feb. 14, 2004</td></tr><tr><td align="left" colspan="2">Fix bug in XPath example</td></tr></table></div></div></div><div></div><hr></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><a href="index.html#introduction">Introduction</a></dt><dt><a href="ar01s02.html">Data Types</a></dt><dt><a href="ar01s03.html">Parsing the file</a></dt><dt><a href="ar01s04.html">Retrieving Element Content</a></dt><dt><a href="ar01s05.html">Using XPath to Retrieve Element Content</a></dt><dt><a href="ar01s06.html">Writing element content</a></dt><dt><a href="ar01s07.html">Writing Attribute</a></dt><dt><a href="ar01s08.html">Retrieving Attributes</a></dt><dt><a href="ar01s09.html">Encoding Conversion</a></dt><dt>A. <a href="apa.html">Compilation</a></dt><dt>B. <a href="apb.html">Sample Document</a></dt><dt>C. <a href="apc.html">Code for Keyword Example</a></dt><dt>D. <a href="apd.html">Code for XPath Example</a></dt><dt>E. <a href="ape.html">Code for Add Keyword Example</a></dt><dt>F. <a href="apf.html">Code for Add Attribute Example</a></dt><dt>G. <a href="apg.html">Code for Retrieving Attribute Value Example</a></dt><dt>H. <a href="aph.html">Code for Encoding Conversion Example</a></dt><dt>I. <a href="api.html">Acknowledgements</a></dt></dl></div><div class="abstract"><p class="title"><b>Abstract</b></p><p>Libxml is a freely licensed C language library for handling
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Libxml Tutorial</title><meta name="generator" content="DocBook XSL Stylesheets V1.61.2"><link rel="home" href="index.html" title="Libxml Tutorial"><link rel="next" href="ar01s02.html" title="Data Types"></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">Libxml Tutorial</th></tr><tr><td width="20%" align="left"> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s02.html">Next</a></td></tr></table><hr></div><div class="article" lang="en"><div class="titlepage"><div><div><h1 class="title"><a name="id2473660"></a>Libxml Tutorial</h1></div><div><div class="author"><h3 class="author"><span class="firstname">John</span> <span class="surname">Fleck</span></h3></div></div><div><p class="copyright">Copyright © 2002, 2003 John Fleck</p></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr><tr><td align="left">Revision 1</td><td align="left">June 4, 2002</td></tr><tr><td align="left" colspan="2">Initial draft</td></tr><tr><td align="left">Revision 2</td><td align="left">June 12, 2002</td></tr><tr><td align="left" colspan="2">retrieving attribute value added</td></tr><tr><td align="left">Revision 3</td><td align="left">Aug. 31, 2002</td></tr><tr><td align="left" colspan="2">freeing memory fix</td></tr><tr><td align="left">Revision 4</td><td align="left">Nov. 10, 2002</td></tr><tr><td align="left" colspan="2">encoding discussion added</td></tr><tr><td align="left">Revision 5</td><td align="left">Dec. 15, 2002</td></tr><tr><td align="left" colspan="2">more memory freeing changes</td></tr><tr><td align="left">Revision 6</td><td align="left">Jan. 26. 2003</td></tr><tr><td align="left" colspan="2">add index</td></tr><tr><td align="left">Revision 7</td><td align="left">April 25, 2003</td></tr><tr><td align="left" colspan="2">add compilation appendix</td></tr><tr><td align="left">Revision 8</td><td align="left">July 24, 2003</td></tr><tr><td align="left" colspan="2">add XPath example</td></tr><tr><td align="left">Revision 9</td><td align="left">Feb. 14, 2004</td></tr><tr><td align="left" colspan="2">Fix bug in XPath example</td></tr><tr><td align="left">Revision 7</td><td align="left">Aug. 24, 2004</td></tr><tr><td align="left" colspan="2">Fix another bug in XPath example</td></tr></table></div></div></div><div></div><hr></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><a href="index.html#introduction">Introduction</a></dt><dt><a href="ar01s02.html">Data Types</a></dt><dt><a href="ar01s03.html">Parsing the file</a></dt><dt><a href="ar01s04.html">Retrieving Element Content</a></dt><dt><a href="ar01s05.html">Using XPath to Retrieve Element Content</a></dt><dt><a href="ar01s06.html">Writing element content</a></dt><dt><a href="ar01s07.html">Writing Attribute</a></dt><dt><a href="ar01s08.html">Retrieving Attributes</a></dt><dt><a href="ar01s09.html">Encoding Conversion</a></dt><dt>A. <a href="apa.html">Compilation</a></dt><dt>B. <a href="apb.html">Sample Document</a></dt><dt>C. <a href="apc.html">Code for Keyword Example</a></dt><dt>D. <a href="apd.html">Code for XPath Example</a></dt><dt>E. <a href="ape.html">Code for Add Keyword Example</a></dt><dt>F. <a href="apf.html">Code for Add Attribute Example</a></dt><dt>G. <a href="apg.html">Code for Retrieving Attribute Value Example</a></dt><dt>H. <a href="aph.html">Code for Encoding Conversion Example</a></dt><dt>I. <a href="api.html">Acknowledgements</a></dt></dl></div><div class="abstract"><p class="title"><b>Abstract</b></p><p>Libxml is a freely licensed C language library for handling
|
||||
<span class="acronym">XML</span>, portable across a large number of platforms. This
|
||||
tutorial provides examples of its basic functions.</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="introduction"></a>Introduction</h2></div></div><div></div></div><p>Libxml is a C language library implementing functions for reading,
|
||||
creating and manipulating <span class="acronym">XML</span> data. This tutorial
|
||||
|
||||
@ -1 +1 @@
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Index</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="api.html" title="I. Acknowledgements"></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">Index</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="api.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> </td></tr></table><hr></div><div class="index"><div class="titlepage"><div><div><h2 class="title"><a name="id2902957"></a>Index</h2></div></div><div></div></div><div class="index"><div class="indexdiv"><h3>A</h3><dl><dt>attribute</dt><dd><dl><dt>retrieving value, <a href="ar01s08.html">Retrieving Attributes</a></dt><dt>writing, <a href="ar01s07.html">Writing Attribute</a></dt></dl></dd></dl></div><div class="indexdiv"><h3>C</h3><dl><dt>compiler flags, <a href="apa.html">Compilation</a></dt></dl></div><div class="indexdiv"><h3>E</h3><dl><dt>element</dt><dd><dl><dt>retrieving content, <a href="ar01s04.html">Retrieving Element Content</a></dt><dt>writing content, <a href="ar01s06.html">Writing element content</a></dt></dl></dd><dt>encoding, <a href="ar01s03.html">Parsing the file</a>, <a href="ar01s09.html">Encoding Conversion</a></dt></dl></div><div class="indexdiv"><h3>F</h3><dl><dt>file</dt><dd><dl><dt>parsing, <a href="ar01s03.html">Parsing the file</a>-<a href="ar01s03.html">Parsing the file</a></dt><dt>saving, <a href="ar01s06.html">Writing element content</a></dt></dl></dd></dl></div><div class="indexdiv"><h3>X</h3><dl><dt>xmlChar, <a href="ar01s02.html">Data Types</a></dt><dt>xmlDoc, <a href="ar01s02.html">Data Types</a></dt><dt>xmlNodePtr, <a href="ar01s02.html">Data Types</a></dt></dl></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="api.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="index.html">Up</a></td><td width="40%" align="right"> </td></tr><tr><td width="40%" align="left" valign="top">I. Acknowledgements </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> </td></tr></table></div></body></html>
|
||||
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Index</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="api.html" title="I. Acknowledgements"></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">Index</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="api.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> </td></tr></table><hr></div><div class="index"><div class="titlepage"><div><div><h2 class="title"><a name="id2588704"></a>Index</h2></div></div><div></div></div><div class="index"><div class="indexdiv"><h3>A</h3><dl><dt>attribute</dt><dd><dl><dt>retrieving value, <a href="ar01s08.html">Retrieving Attributes</a></dt><dt>writing, <a href="ar01s07.html">Writing Attribute</a></dt></dl></dd></dl></div><div class="indexdiv"><h3>C</h3><dl><dt>compiler flags, <a href="apa.html">Compilation</a></dt></dl></div><div class="indexdiv"><h3>E</h3><dl><dt>element</dt><dd><dl><dt>retrieving content, <a href="ar01s04.html">Retrieving Element Content</a></dt><dt>writing content, <a href="ar01s06.html">Writing element content</a></dt></dl></dd><dt>encoding, <a href="ar01s03.html">Parsing the file</a>, <a href="ar01s09.html">Encoding Conversion</a></dt></dl></div><div class="indexdiv"><h3>F</h3><dl><dt>file</dt><dd><dl><dt>parsing, <a href="ar01s03.html">Parsing the file</a>-<a href="ar01s03.html">Parsing the file</a></dt><dt>saving, <a href="ar01s06.html">Writing element content</a></dt></dl></dd></dl></div><div class="indexdiv"><h3>X</h3><dl><dt>xmlChar, <a href="ar01s02.html">Data Types</a></dt><dt>xmlDoc, <a href="ar01s02.html">Data Types</a></dt><dt>xmlNodePtr, <a href="ar01s02.html">Data Types</a></dt></dl></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="api.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="index.html">Up</a></td><td width="40%" align="right"> </td></tr><tr><td width="40%" align="left" valign="top">I. Acknowledgements </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> </td></tr></table></div></body></html>
|
||||
|
||||
File diff suppressed because it is too large
Load Diff
@ -67,6 +67,11 @@
|
||||
<date>Feb. 14, 2004</date>
|
||||
<revremark>Fix bug in XPath example</revremark>
|
||||
</revision>
|
||||
<revision>
|
||||
<revnumber>7</revnumber>
|
||||
<date>Aug. 24, 2004</date>
|
||||
<revremark>Fix another bug in XPath example</revremark>
|
||||
</revision>
|
||||
</revhistory>
|
||||
</articleinfo>
|
||||
<abstract>
|
||||
@ -369,11 +374,9 @@ parseStory (xmlDocPtr doc, xmlNodePtr cur) {
|
||||
<co id="cocreatecontext" />context = xmlXPathNewContext(doc);
|
||||
<co id="corunxpath" />result = xmlXPathEvalExpression(xpath, context);
|
||||
<co id="cocheckxpathresult" />if(xmlXPathNodeSetIsEmpty(result->nodesetval)){
|
||||
xmlXPathFreeObject(result);
|
||||
printf("No result\n");
|
||||
return NULL;
|
||||
}
|
||||
xmlXPathFreeContext(context);
|
||||
return result;
|
||||
return NULL;
|
||||
</programlisting>
|
||||
<calloutlist>
|
||||
<callout arearefs="cocontext">
|
||||
@ -386,7 +389,8 @@ parseStory (xmlDocPtr doc, xmlNodePtr cur) {
|
||||
<para>Apply the <application>XPath</application> expression.</para>
|
||||
</callout>
|
||||
<callout arearefs="cocheckxpathresult">
|
||||
<para>Check the result.</para>
|
||||
<para>Check the result and free the memory allocated to
|
||||
<varname>result</varname> if no result is found.</para>
|
||||
</callout>
|
||||
</calloutlist>
|
||||
</para>
|
||||
|
||||
Loading…
Reference in New Issue
Block a user