Qt how to open a file in current dir ? or what's wrong with this?

Try to use QCoreApplication::applicationDirPath() instead of QDir::currentPath().

For details see http://doc.qt.io/qt-5/qcoreapplication.html#applicationDirPath

Check the returned value of QDir::currentPath(). I think when you run from Qt Creator, it returns the path where the project file (*.pro) is located. When you run from outside, you get path of the binary.

Edit

I never worked with Linux. However, you can try other functions/combinations from QDir:

• QDir::current().path()
• QDir::current().absolutePath()

etc.

To open a file in the current directory, you simply call QFile constructor

I tested this on my Linux machine and it works

#include <QtCore>

int main(int argc, char** argv){
    QFile some_file("test.xml");
    if(!some_file.open(QIODevice::ReadOnly | QIODevice::Text)){
        qDebug() << "Unable to open file";
    } else {
        qDebug() << "File open successfully";
    }
    exit(-1);
}

I run ./TestQFile and if there is a test.xml in the current directory, it works.

UPDATE: I notice that the wording of your question says that you want the file in the same directory as the executable, this can be done as follow:

// Getting directory of the executable
QFileInfo exec_fileinfo(argv[0]);
qDebug() << "Executable is in" << exec_fileinfo.absolutePath();

UPDATE 2: Under the project panel of QtCreator, there is a field for Working Directory. This is the directory that is returned by QDir::currentPath() if you are running it via QtCreator.