xerces: how to take xml node with a particular tag?

Question

with Qt library I can take a node with a particular tag name with:

QDomElement tmp = root.firstChildElement("A");
QDomElement tt = tmp.firstChildElement("C");

with a xml file with this structure:

<A>
<B></B>
<C></C>
</A>

With xerces, how can I do this?

Answer 1

xercesc_3_2::XMLPlatformUtils::Initialize();
// create the DOM parser
xercesc_3_2::XercesDOMParser* parser = new xercesc_3_2::XercesDOMParser;
parser->setValidationScheme(xercesc_3_2::XercesDOMParser::Val_Never);
parser->parse(fileName.c_str());
// get the DOM representation
xercesc_3_2::DOMDocument* doc = parser->getDocument();
// get the root element
xercesc_3_2::DOMElement* root = doc->getDocumentElement();

// evaluate the xpath
xercesc_3_2::DOMXPathResult* result = doc->evaluate(
    xercesc_3_2::XMLString::transcode("/doc/document/childL1/childL2/Node_to_change"), // "A/B" in the provided xml sample for change B text node value
    root,
    NULL,
    xercesc_3_2::DOMXPathResult::ORDERED_NODE_SNAPSHOT_TYPE,
    NULL);

And also change the value:

if (result->getNodeValue() == NULL)
{
    cout << "There is no result for the provided XPath " << endl;
}
else
{

    result->getNodeValue()->getFirstChild()->setNodeValue(xercesc_3_2::XMLString::transcode("3000"));
    const XMLCh* a = result->getNodeValue()->getFirstChild()->getNodeValue();
    char* tttt = (char*)a;
    cout << "Node value: " << tttt << endl;
    
}