Before Qt 5, the old connect syntax was the only option. It looks as follows:
connect(spinBox, SIGNAL(valueChanged(int)), dial, SLOT(setValue(int)));
This statement establishes a connection between the signal of the spinBox object called valueChanged that carries an int parameter and a setValue slot in the dial object that accepts an int parameter. It is forbidden to put argument names or values in a connect statement. Qt Creator is usually able to suggest all possible inputs in this context if you press Ctrl + Space after SIGNAL( or SLOT(.
While this syntax is still available, we discourage its wide use, because it has the following drawbacks:
- If the signal or the slot is incorrectly referenced (for example, its name ...