pre-defined funcitons definition

A few days ago I decided to add some functions to unity’s pre-defined (e.g. Start() , OnMouseDown() )functions. However I don’t know which file are they defined in? (I know unity is not open source but they have to be somewhere in the computer, right?) Do you have any idea where are pre-deifned funcitons are defined?

I want to make my own funcitons for example double click or long click etc.

Thanks from now.

Unity is not open source, so you can’t really change those methods. Can’t exactly say more without knowing what you want to do

You can have methods (functions) in your classes, the problem is, who’s calling them? Unity calls Start() and OnMouseDown() is called by the camera that’s set to send events. If you have some event system (you can also extend the EventSystem and InputModule to generate double click events), then what it does it just calls some method on your scripts, there’s nothing Unity specific happening.