XML -read-write

I used read(QIODevice *device) and write(QIODevice *device) functions for reading and writing.I could read infos from xml.I wanted to change only a text.
<Name>xxxxx</Name> to <Name> yyyyy </Name>
But I couldnt find the function.(Ex:setText() or setValue())
In examples I saw that everything is created again.But This is too long for only a text.
Is there a way for writing XML?

See QtXml module.

I read.These are my write functions.I can change value but not in xml file.I cant write new value to xml file.Will I change all file?

Code:

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bool Data::WriteParameter(Parameter *parameter, std::vector<unsigned int> Indexes)
{
 
	QFile programFile(PARAMETER_FILE);//xml verildi
	QDomElement element;//xml üzerinde işlem yapacak
	XML_File xmlData;//bu file bu sinif içinde açılacak
	bool result=false;
 
	xmlData.read(&programFile);
	element=xmlData.domDocument.documentElement();
	if(element.tagName()=="Parameters" && element.hasChildNodes()==true)
	{
		element=element.firstChildElement();
		do
		{
			if(element.tagName().toStdString()==parameter->getName())
			{
				ChangeParameter(parameter,element,Indexes);
				result=true;
				break;
			}
			else
			{
				element=element.nextSiblingElement();
			}
		}while(!element.isNull());
 
		xmlData.write(&programFile);
	}
	return result;
 
}
 
void Data::ChangeParameter(Parameter *parameter, QDomElement element,std::vector<unsigned int> Indexes)
{
	unsigned int index;
	QString tagName;
	QDomElement _element;QDomCharacterData dataLn;
	QDomText elementText;
	QDomNodeList parameterList,elementList;
	parameterList=element.childNodes();
	vector<unsigned int>::iterator itr;
	for(itr=Indexes.begin();itr!=Indexes.end();itr++)
	{
		elementList=parameterList.item(*itr).toElement().childNodes();		
		for(index=0;index<(unsigned int)elementList.size();index++)
		{
			_element=elementList.item(index).toElement();
			tagName=_element.tagName();
			if(tagName=="Value")
			{
				elementText=_element.childNodes().item(0).toText();
				dataLn=elementText.toCharacterData();
				//elementText.setNodeValue(QString::number(parameter->Parameters[*itr]->getValue()));
				dataLn.replaceData(0,QString::number(parameter->Parameters[*itr]->getValue()).length(),
						QString::number(parameter->Parameters[*itr]->getValue()));
			}
		}
	}
}
 
bool XML_File::write(QIODevice *device)
{
 
     const int IndentSize = 4;
 
     QTextStream out(device);
     domDocument.save(out, IndentSize);
     return true;
}

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