This (int) msg.wParam; makes the exit code of the process to be the same as the one passed to PostQuitMessage() function; typically it is ignored for most purposes, so returning always 0 makes the code simpler.
Thank you very much. And after further analysis, the visual c++ win32 api tutorial was just showing how to use visual c++ (I think). The reason I say I think is because I don't know if there is more. The website is weird. When you collapse a menu, everything below it disappears.
Another question please:
What is this:
They are coming before the typedefs so they are not types. I couldn't find definitions for these anywhere in the list of data types or data mappings.
I am very confused. I really REALLY appreciate the help! And I apologize for my ignorance if I ask a silly question with simple answers.
The best way to learn the win32 api is the exact same way you would learn any other library or api... That's to find a tutorial that is good enough to give you a basic understanding of the environment you're working in, then looking at the definitions of key functions and their parameters. A good way to keep yourself from being overwhelmed is to make a goal, as an example, you could make a windows based game that would require log in, save states, check boxes, radio buttons, etc etc, and learn how to do each thing individually as you move along.
As for a resource for the definitions of functions and parameters of the win32 api, it's always best to go to the source for information. In this case it would be Microsoft with MSDN.
The reason I don't refer you to a tutorial is because many tutorials are written by people who learned in a specific way and want to teach you the same way they learned. The reason this is bad is because c++ is an updated language, and many things become obsolete (Such as using GDI/+ etc). Also, it's better to learn for yourself, so that when you reach a problem, you are capable of solving it yourself (and not constantly looking back at tutorials).
TLDR; If you already have a good grasp on programming in general and the language that you're using, then it's best to learn about the functions, parameters, and limitations of the library/api. It's like learning the English language, if you already have a good basic grasp of the language, than a dictionary will always be more useful than a random book.