Changing current path of a Qt Application - c++

Question

I am using Qt Library and I want to set the current path to the path contained in a QString oldConfigFileName and i am using setCurrent() but setCurrent is returning a false value indicating a failure in changing path.
Code:
QString path = QDir::currentPath();
std::string currentpath = path.toStdString();
std::string configPath = oldConfigFileName.toStdString();
bool res = QDir::setCurrent(oldConfigFileName);
if(res)
{
qDebug() << "Path Changed";
}
else
{
qDebug() << "Path not changed";
}

Answer 1

The problem is the path you are using is a full path to a config file containing the file name. When you try to change the directory to this path the command will fail because oldConfigFileName is a file not an existing folder. A simple way to fix this is to use QFileInfo to remove the filename part from the path then use that as the directory.
QFileInfo fi(oldConfigFileName);
bool res = QDir::setCurrent(fi.path());
if(res)
{
qDebug() << "Path Changed";
}
else
{
qDebug() << "Path not changed";
}

Answer 2

Without knowing an actual content of the oldConfigFileName, one reason for failure may be that the path does not exists. It may be good idea to check existance of the path before calling the QDir::setCurrent() -method.
if(!QDir(oldConfigFileName).exists())
{
qDebug() << "Path does not exists.";
// Path does not exists, if needed, it can be created by
// QDir().mkdir(oldConfigFileName);
}
Another reason for the failure may be that oldConfigFileName does not contain valid path string. To check that, I would change debug logs following way:
if(res)
{
qDebug() << "Path Changed";
}
else
{
qDebug() << "Path not changed. Path string = " << oldConfigFileName;
}