Creating new parameters question

[PutraenusAlivius]

So I was learning about creating new functions in the wiki article. Now I was reading about it and I just made a function line like this.

Code: (Select All)

int FUNCTION(sig 1, sig 2, and so on)
{
}

Like so right? But, how do I know that the new parameter will do exactly what I said, I mean what happens if something's wrong? Is it tested that it'll do exactly what I describe?

NOTE: I haven't test it, in fact I just found them today.