QT 调试输出格式

Qt调试输出格式：
    1，qDebug() << qPrintable(firstNode.nodeName())  << qPrintable(firstNode.nodeValue());
2，http://open.21ic.com/open/video/5528
3, QString("select name from brand where type= '%1'").arg(arg1) 

4, lineEdit()->Text().toInt();  setText(QString::number(num));