Important: Please read the Qt Code of Conduct -

Application output "flashes", but my GUI is not displayed on the screen.

  • I have a problem with my project when a start with qDebug.
    In my code I have two .txt files that I need to read in my program. But when I
    put All.txt (my txt file) and dbconf.txt (my txt file) in my Working Directory my GUI doesn't show on screen.
    When I delete All.txt and dbconf.txt, my GUI show but my application has no purpose because I gotta read and write in these text files.
    How can I solve it?

  • Moderators

    It's impossible to help without looking at the code. There can be million number of reasons matching your brief description.

  • this is just a part of my code, but now to view the file I try to open when starting the program.


    //Write all paths in the GUI when start the program.
    _directorydbconf = "dbconf.txt";
    if (!_directorydbconf.isEmpty()) {
            QFile file(_directorydbconf);
            if (! {
                QMessageBox::critical(this, tr("Error"), tr("Could not open file"));
            QTextStream in(&file);
            line1 = in.readLine();
            line12 = line1.mid(4);
            line2 = in.readLine();
            line21 = line2.mid(4);            //Reads from the fourth character
            line3 = in.readLine();
            line31 = line3.mid(4);            //Reads from the fourth character
            line4 = in.readLine();
            line41=line4.mid(4);              //Reads from the fourth character
    QFile file4(_directorydbconf);
    QTextStream in4(&file4);
             qDebug() << "could not open file writing";
    for(int x=0; x<7; x++){
        _text11= in4.readLine();
    for(int x=0; x=7; x++){
    _text21= in4.readLine();


    When I put the dbconf.txt file in the working directory, the GUI does not appear when I remove(dbconf.txt) the GUI file appears but with the mesagem "Could not open file".

  • It looks like there might be an error in your code with where you declare QFile. YOu declare it inside some brackets but I think it is going out of scope where you create a datastream and try to read it Try moving QFile to the top of the program

  • Yes, this is definitely an error. I'm wondering why compiler doesn't throw an error while trying to compile that code...

  • Yes, there are errors.
    As I was learning and riding my application for a long time, I made mistakes I did not realize.
    I modified only the logic to read the file and opened it to read only once.

    Thanks for help! :)

Log in to reply