return valuez

I have a general question about all the functions used in VB games. Say yer using SetCursorPos - You type:

SetCursorPos 10,27

No problem, right? Ok then sometimes I see something like this:

retval = SetCursorPos(10,27)

Then you have some kind of return value coming back at ya. So, what kinda value do these functions return and what are they used for!?

Most of the time, the return value says that the function succeeded (or not).