Segmentation fault (wxString problem)

[kornerr]

I get "Segmentation fault" when try to do

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map->skybox.back.filename = "string";

map is a pointer to Map class.
filename is of wxString class.
I can't understand what's wrong here, because when I do

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map->skybox.back.texid = 1

it doesn't cause the error.
texid is of GLint type.

I even tried to change filename to string type, not wxString class, but with no success. Even memset was done for skybox...

I'm at a loss what to do, and what can cause the error

Can anyone help me?

Thanks.

PS: Sources
(remove ".doc" from the filename)
The sources require wxWidgets and OpenGL (and Linux, or Cygwin under Windows)
Call "Map->Skybox->OK" and you will get "Segmentation fault".

[phlox81]

is filename a pointer ?

[kornerr]

filename is of wxString class

[jazz]

Maybe test it using the wxString::Append() function or similar instead of wxString::operator=. If there is a logical error forcing that may point you in the right direction or it won't compile.

[chris]

Hi kornerr,

I did some debugging on your code and found the problem.

In the ctor of class Map you erase the struct skybox via

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memset (&skybox, 0, sizeof (skybox));

You can't do this with structs having instances of classes (wxString in this case), because you are then also erasing the pointer to the instances.

Another heed of warning: Also do not try to copy one struct with instances to another w/ memcpy or others. This will lead to similar problems.

HTH, chris

[kornerr]

Thanks very much, chris.
Can you tell me where did you know such "profound" things about C++?
I've only read Thinking in C++, vol1 (without polymorphism and templates )

Thanks.

[chris]

Hi kornerr,

don't worry, deeper understanding of languages comes IMHO in greatest parts by simply doing it -- it's a bit like a recursion: you learn programming thru programming
I've got several years of OO programming (C++ and Java) on my back now, but I still make errors. It just happens; make the best of it and learn thru your errors. Once you made one, remember how that happened, and next time you'll know better.
Regarding literature: I had some good experiences with the "in a nutshell" books from O'Reilly (e.g. see http://www.oreilly.com/catalog/cplsian/ for "C++ in a nutshell"). They aren't cheap, but good for both beginners and professionals.
It'll be hard at first, but I recommend reading thru all the core properties of a language at once. After that, you'll know where to look in the book if you got a problem with a specific part of a language.

HTH, Chris

[kornerr]

Thanks, chris.