button question

[aegis]

I gave you the 'guide', what more do you need?
1. create a slot
2. connect the clicked() signal to that slot
3. in the slot emit the event

in the book c++ gui programming with qt4 i found another way{create an action, populate a menu, connect the menu with button}

oneAction= new QAction("do something!!", this);
connect(oneAction, SIGNAL(triggered()), this, SLOT(action()));
processMenu->addAction(oneAction);
menuButton->setMenu(&processMenu);

oneAction= new QAction("do something!!", this);
connect(oneAction, SIGNAL(triggered()), this, SLOT(action()));
processMenu->addAction(oneAction);
menuButton->setMenu(&processMenu);

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what is the difference? between these 2 ways?