C++ XML parser QT - not working

Below is my code & xml file. I am trying to read a xml file and store the contents. But its not working. Please help

int ParseConfigFile::populateUserValues ( string &OS, string &dir, string &logPath )
{
    QDomDocument doc;
    QDomElement element;

    QFile file("config_v1.xml");

    if ( doc.setContent( file.readAll() ) == false )
 开发者_开发技巧       return 1;

    element = doc.documentElement();

    QDomNodeList list = element.childNodes();
    QDomElement firstChild = list.at(0).toElement(); // will return the first child
    QDomElement secondChild = list.at(1).toElement();
    QDomElement thirdChild = list.at(2).toElement();


    QString s1,s2,s3;
    s1 = firstChild.text();
    s2 = secondChild.text();
    s3 = thirdChild.text();

    OS = s1.toStdString();
    dir = s2.toStdString();
    logPath = s3.toStdString();

    return 0;
}

and my XML

<?xml version="1.0"?>
<config>
  <type>LINUX</type>
  <dir>/home/</dir>
  <path>/var/log/</path>
</config>

You should instantiate the QDomDocument like this and then your code will work:

if ( doc.setContent(&file) == false )
        return 1;

QDomDocument can work with an IO device (like QFile) making this the optimum way to set the QDomDocument's content from a file.

Anyway, if you're trying to write a configuration file reader/writer I suggest you stick with QSettings

QSettings settings("MyCompany", "MyApp");
QString s1,s2,s3;
s1 = settings.value("type").toString();
s2 = secondChild..value("dir").toString();
s3 = thirdChild..value("path").toString();

The configuration file format won't be XML (it will be key=value) but you will hardly ever need to worry about the file itself. To set any value on the file is also easy:

QSettings settings("MyCompany", "MyApp");
settings.setValue("path", "/var/log/");

Your configuration file will look like this:

[General]
path=/var/log/

See: QSettings documentation