Pointer to Pointer problem

Yes indeedy. Just to clarify on what Mr. AP said, if you're doing something like this:

CPolygon **ppPolygon;*ppPolygon = pPolygon;

That is very bad. What you're doing in that second line is trying to dereference the pointer ppPolygon, when it hasn't even been assigned a value. This will almost certainly result in a segfault, as ppPolygon will have some invalid value, probably NULL or 0xCDCDCDCD or something like that.

In any case, that line (*ppPolygon = pPolygon) is not storing the address of pPolygon and storing it in ppPolygon: it is taking the value of pPolygon and storing it in the location that ppPolygon points to, which as I noted before, will not be a valid memory location.

0) Like they said.
1) This could reasonably go in For Beginners.
2) Just say no to VC++6. Get yourself something at least half-decently modern and up to the current language spec. There are *several, free* options for doing so, so there's really no excuse.
3) There's probably no good reason for explicitly creating a pointer to a pointer to a Polygon. What are you trying to do?

Quote:

Original post by Zahlman 2) Just say no to VC++6. Get yourself something at least half-decently modern and up to the current language spec. There are *several, free* options for doing so, so there's really no excuse.

*cough* Including Visual Studio 2005 Express, free (legally!) from Microsoft. *cough*

Same product, only made after there actualy was a C++ standard at all to comply with. Something I can call a C++ compiler without feeling like I'm lying.