Hi everyone. I'm using a third party library in my app written in C, which uses a lot of printf statements. I wanted to redirect that prints to a textEdit on my app. So with the help of others I wrote a redirection function, which redirects stdout to a file and adds text to my textEdit whenever content of file changes. So far so good everything works ok. However at the end external lib call I would like to quit that redirection and delete the file as well, but when I do so I get an error that redirection file does not exist anymore. This would probably mean that signal/slot connection still exists. How can I fix this? Much thanks for help in advance. The code looks like this:
Qt Code: 
  1. void MainWindow::RedirectOutput(int type) {
  2.     QFileSystemWatcher * watcher = new QFileSystemWatcher(this);
  3.     if (type==0) {
  4.         // redirect stdout to file
  5.         freopen("redirect.txt","w",stdout);
  6.  
  7.         // disable buffering
  8.         setvbuf(stdout,NULL,_IONBF,0);
  9.  
  10.         // check if file changed
  11.  
  12.         watcher->addPath("redirect.txt");
  13.         connect(watcher,SIGNAL(fileChanged(QString)),this,SLOT(HandleFileChange(QString)));
  14.     } else {
  15.         // reenable buffering, not really needed
  16.         //setvbuf(stdout,NULL,_IOFBF,4000);
  17.  
  18.         //return stdout to display
  19.         freopen( "CON","w",stdout);
  20.         disconnect(watcher,SIGNAL(fileChanged(QString)),this,SLOT(HandleFileChange(QString)));  //<doesnt' work
  21.         if (QFile::exists("redirect.txt"))
  22.             QFile::remove("redirect.txt");
  23.     }
  24. }
  25.  
  26. void MainWindow::HandleFileChange(const QString filename){
  27.     QFile f(filename);
  28.     if (f.open(QIODevice::ReadOnly)) {
  29.         //QMessageBox::information(this,"info",QString::number(f.size()));
  30.         f.seek(fbytes);
  31.         const QByteArray ba = f.readAll();
  32.         fbytes += ba.size();
  33.         //QMessageBox::information(this,"stdout",filename + " changed:\n\n" + ba);
  34.         //cout << qPrintable(ba) << endl;
  35.         ui->textEdit->append(qPrintable(ba));
  36.     } else {
  37.         QMessageBox::critical(this,"stdout","Can't open file");
  38.     }
  39. }
To copy to clipboard, switch view to plain text mode