Why a directory string loss '/' will return the parent qdir in Qt - qt

Question

It maybe a bug. Please read webclectic answer.
If QFileInfo(filename) loss '/', QDir::absolutePath will return the parent string. Like below code.
QFileInfo file("e:/QtExample/mytest/out/res/res1/");
QFileInfo file_no("e:/QtExample/mytest/out/res/res1");
QDir dirFile = file.absoluteDir();
QDir dirFile_no = file_no.absoluteDir();
QString strDirFile = dirFile.absolutePath(); //"E:/QtExample/mytest/out/res/res1
QString strDirFile_no = dirFile_no.absolutePath(); //"E:/QtExample/mytest/out/res
I found it with my QTreeView. My code will call the slot from QTreeView::clicked signals
connect(ui.m_pView,SIGNAL(clicked(QModelIndex)),this,SLOT(myClicked(QModelIndex)));
the slot will get the QModelIndex, then I use QFileSystemMode::fileInfo get the QFileInfo.
QFileInfo rFileInfo = m_model.fileInfo(index);
QDir absDir = rFileInfoDir.absoluteDir();
But the return of QFileInfo always return "e:/QtExample/mytest/out/res/res", so If I call QFileInfo::absoluteDir get the directory, the directory is the parent of "res1".So I will get wrong entrylst from my hope directory.
Should I add the '/' after the absoluteFilePath() to get the right QDir?
And why strDirPath equal "E:/QtExample/mytest/out/res/res1", but rDir will list the "res" directory entrylist?
//rFileInfoDir == E:/QtExample/mytest/out/res/res1
QString strDirPath = rFileInfoDir.absoluteFilePath();
QDir rDir = rFileInfoDir.absoluteDir();

Answer 1

If you go deep into the absoluteDir() function call you will see why this happens. In Windows the fileName function in qfsfileengine_win.cpp is called. In this function there is this code part:
if (file == AbsolutePathName) {
int slash = ret.lastIndexOf(QLatin1Char('/'));
if (slash < 0)
return ret;
else if (ret.at(0) != QLatin1Char('/') && slash == 2)
return ret.left(3); // include the slash
else
return ret.left(slash > 0 ? slash : 1);
}
You can see that it returns the part of the string left of the last separator. I don't know if this is the desired behavior or a bug. Maybe you could issue a Qt bug for this. The documentation is not clear on this matter.

Answer 2

From the QFileInfo::absoluteDir() docs:
Returns the file's absolute path as a QDir object.
In the case of "/foo/bar", the file is "bar" and its directory is /foo. It doesn't matter if bar is a directory or a plain file, as directories are also files. If you want something like "for files, return the parent directory, for directories, return the directory itself", you'll have to write your own little function testing via QFileInfo::isDir for what to return.

Answer 3

e:/QtExample/mytest/out/res/res1/res is the path to a directory called "res", e:/QtExample/mytest/out/res/res1/ is the path to an empty directory (called ""). So whether you should add a slash or not depends on what you are trying to do.
In my own personal opinion it's better not to add a final slash because it's easy to add it if you need to, while removing it is not as straightforward.