With this variable you can get the keycode of the key that is currently being pressed and it will return 0 if no key is being pressed when the check is done.
case vk_numpad1: gun = weapon[0,0]; break;
case vk_numpad2: gun = weapon[1,0]; break;
case vk_numpad3: gun = weapon[2,0]; break;
The above code uses the value of the keyboard_key variable to set a variable to the same value as an array.