在Qt中打开和读取文件

Question

I am trying to use the menu bar to open a file (hardcoded) when 'File|Open' is clicked. The file should append to and display each line. My function is not finding the file. So after I click open I am getting back 'trace.txt cannot be found'. I have the file saved in the same directory as the rest of the project files. I am wondering if I haven't opened the file properly? Can anyone have a look at my code and see if you're catching an error that I am not?

void MainWindow::readFile(){
    infoLabel->setText(tr("Invoked <b>File|Open</b>"));
    QString filename="trace.txt";
    QFile file(filename);
    if(!file.exists()){
        qDebug() << "File <i>cannot</i> be found "<<filename;
    }else{
        qDebug() << filename<<" Opening...";
    }
    QString line;
    textEdit->clear();
    if (file.open(QIODevice::ReadOnly | QIODevice::Text)){
        QTextStream stream(&file);
        while (!stream.atEnd()){
            line = stream.readLine();
            textEdit->setText(textEdit->toPlainText()+"0x"+line+"\n");
            qDebug() << "line: "<<line;
        }
    }
    file.close();
}

UPDATE: I changed the QFile object to the direct path and that found the file. On the other hand, I am reading it in an infinite loop, which never makes it to the textEdit and continually outputs to the debugger. Any ideas?

Answer 1

Use current or currentPath() to see with which directory you are working. See this example to understand the current directory:

QFile file;
QDir::setCurrent("/tmp");
file.setFileName("readme.txt");
QDir::setCurrent("/home");
file.open(QIODevice::ReadOnly);      // opens "/home/readme.txt" under Unix

From http://doc.qt.io/qt-5/qfile.html#QFile