General Qt Questions

Question

I learned the basics of Qt and am now interested in the depths of this pretty library. Please help me understand:

• Are all classes derived from QObject ?
• Why is it possible to draw on QWidget (and derived classes)?
• What does the string return app.exec(); mean return app.exec(); ? What does the exec () method do?
• Are there virtual slots ? And virtual signals ?

Thanks.

Answer 1

• All classes that need Qt (for example, using signals and slots) must be obtained from QObject.
• So that you can implement your own custom widgets. Any reasonable GUI library will allow you to do this.
• As stated in the document , it is part of the Qt event loop.
• Slots can be virtual. Since signals have no implementation (or, rather, moc generates their implementation), they cannot be virtual.

Qt has really good and extensive documentation, if you have more questions then they probably already answered there. Start by programming with Qt .