Below is the implementation of QInputDialog::getText from Qt 4.7
Qt Code: 
  1. QString QInputDialog::getText(QWidget *parent, const QString &title, const QString &label,
  2.                               QLineEdit::EchoMode mode, const QString &text, bool *ok,
  3.                               Qt::WindowFlags flags)
  4. {
  5.     QInputDialog dialog(parent, flags);
  6.     dialog.setWindowTitle(title);
  7.     dialog.setLabelText(label);
  8.     dialog.setTextValue(text);
  9.     dialog.setTextEchoMode(mode);
  10.  
  11.     int ret = dialog.exec();
  12.     if (ok)
  13.         *ok = !!ret;
  14.     if (ret) {
  15.         return dialog.textValue();
  16.     } else {
  17.         return QString();
  18.     }
  19. }
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My question is about line 13. First I thought !! is used to convert int to bool, but soon I realized the conversion takes place automatically. Is it something special about !! ?