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Message-ID: <3E4000E0.9040103@boris-glawe.de>
Date: Tue, 04 Feb 2003 19:05:20 +0100
From: Boris Glawe <boris@boris-glawe.de>
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To: xerces-c-dev@xml.apache.org
Subject: Re: getNodeValue() crashes
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David N Bertoni/Cambridge/IBM wrote:

>
>   1. XMLString::transcode() returns a pointer to dynamic memory that you
>   must delete.  If you don't, it's a memory leak:
>
>      char* str = XMLString::transcode(...);
>
>      delete [] str;
>  
>
I am assigning this value to a string... do I have to delete this 
string, too ??

>   2. Element nodes have no value, so getValue() is probably returning a
>   null pointer.  The "value" of an Element is contained in its Text
>   children, so you must iterate through the children to get the value.
>
According to the API getNodeValue() returns a const XMLCh*.. what does 
the returnvalue contain, if not the text of the node 'element' ?? Even 
if it returns null, why does it crash ?? this null value should be 
assigned to string....!??

Do you have any hints, which classes/methods/mechanisms to use, when 
iterating through the Text Children ??

thanks Boris

>I am a beginner, so hope you're not bored with my problem...
>
>I am using gcc3.2 on Redhat 8.0... I compiled the xerces-c library
>myself...
>The program crashes, as soon, as I try to call the getNodeValue() method
>of a DOMNode...
>The used xml file  (test.xml) is at the bottom....
>According to the API all types are correct... What am I doing wrong ??
>Read the comments in the prgram
>for further information.
>It compiles without any warnings (though -Wall), and without errors...
>Maybe, I've something done wrong, when compiling the xerces-c library
>(I used './runConfigure -p linux -c gcc -x g++' and  then 'gmake' as
>recommended in the docs)??
>
>//#####################################
>#include <iostream>
>#include <string>
>
>#include <xercesc/dom/DOM.hpp>
>#include <xercesc/parsers/XercesDOMParser.hpp>
>#include <xercesc/util/PlatformUtils.hpp>
>#include <xercesc/sax/HandlerBase.hpp>
>
>using namespace std;
>
>int main(int argc, char* argv[]) {
>
>try {
>  XMLPlatformUtils::Initialize();
>}
>catch(const XMLException& toCatch){
>cout << "Exception message is:" <<
>XMLString::transcode(toCatch.getMessage())
>                         << endl;
>return -1;
>}
>
>XercesDOMParser* parser = new XercesDOMParser();
>
>ErrorHandler* err = (ErrorHandler*) new HandlerBase();
>parser->setErrorHandler(err);
>
>
>char* xmlFile = "/home/boris/test.xml";
>
>try {
>parser->parse(xmlFile);
>}
>catch (XMLException& toCatch){
>cout << "Exception is: " << XMLString::transcode (toCatch.getMessage())
><< endl;
>return -1;
>}
>catch (DOMException& toCatch){
>cout << "Exception is: " << XMLString::transcode (toCatch.msg) << endl;
>return -1;
>}
>catch (...) {
>cout << "unexpected Exception: " << endl;
>return -1;
>}
>
>DOMDocument* doc = parser->getDocument();
>DOMNodeList* list =
>doc->getElementsByTagName(XMLString::transcode("element"));
>string text = "";
>
>DOMNode* node = list->item(0);
>//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>
>/*Problem starts here... program crashes when calling getNodeValue()
>  * tried also char* as type for text. Shouldn't it assign the value
>  * 'hallo' to the string text ??
>  */
>
>if (node){
>             text = XMLString::transcode(node->getNodeValue());
>             //program crashes here....!!!!!!!!!!!!!!!
>             }
>else {
>             // node ist not null, thus this is not executed..
>             cout << "Failure: maybe node is empty" << endl;
>             }
>cout << text << endl;
>
>//this does also not work
>//cout << XMLString::transcode(list->item(0)->getNodeValue()) << endl;
>
>//this again works, when commenting out the code above.. and shows
>//the name 'element' and that there is one element in the nodelist...
>cout << XMLString::transcode(list->item(0)->getNodeName()) << endl;
>cout << list->getLength() << endl;
>
>cout << "Exiting normally" << endl;
>return 0;
>
>}
>
>
>########## test.xml ########################################
>
><?xml version="1.0"?>
>
><test xmlns="http://www.boris-glawe.de/">
>  <element>
>   hallo
>  </element>
></test>
>
>
>
>
>
>
>
>--
>Stop TCPA and Palladium !!!
>
>watch these sites if you want to learn more:
>
>english:
>http://www.cl.cam.ac.uk/~rja14/tcpa-faq.html
>
>german:
>http://moon.hipjoint.de/tcpa-palladium-faq-de.html
>
>
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>  
>


-- 
Stop TCPA and Palladium !!!

watch these sites if you want to learn more:

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http://www.cl.cam.ac.uk/~rja14/tcpa-faq.html

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