The "slot machine" term derives from the slots on the machine for inserting and retrieving coins. "Fruit machine" comes from the traditional fruit on the spinning reels such as lemons and cherries.
A slot is a narrow opening in a machine or container, for example a hole that you put coins in to make a machine work. He dropped a coin into the slot and dialled the number. If you slot something into something else, or if it slots into it, you put it into a space where it fits. He was slotting a CD into a CD player.
To connect the signal to the slot, we use QObject::connect(). There are several ways to connect signal and slots. The first is to use function pointers: connect(sender, &QObject::destroyed, this, &MyObject::objectDestroyed);
To begin connecting objects, enter the signals and slots editing mode by opening the Edit menu and selecting Edit Signals/Slots, or by pressing the F4 key. All widgets and layouts on the form can be connected together. However, spacers just provide spacing hints to layouts, so they cannot be connected to other objects.
