My First Class!!

algumacoisaqualquer · 2002-08-10T21:13:08

This is the first time i have used a class structure on a real project. It works fine while the program is running, but I get an ilegal error when I close the program. First of all, i have no idea of how the destructor work, so i made one but I never call him. Anyway, i'm going to post the class here, i would apreciate any comments you have: //////////////// //The header: // //////////////// #ifndef CPK_MAP_CLASS_H #define CPK_MAP_CLASS_H class LevelMap { // It's a map class, it stores the info of the map // that is displayed in the screen right now (the ScreenMap // array) and the info of the World map (the Map array). // SizeX, SizeY are the sizes of the world map, // ScreenX, ScreenY are the number of tiles in the ScreenMap // MapX, MapY are the coordinates of where the ScreenMap is // in relation with the world Map, So ScreenMap(0,0) stores // the value of Map(MapX, MapY). public: char *ScreenMap; LevelMap(); LevelMap(int map_x, int map_y, int screen_x, int screen_y); ~LevelMap(); char GetAbsoluteTile(int x, int y); char GetTile(int x, int y); bool LevelMap::CreateMap(); bool LevelMap::SetTile(int x, int y, char Value); bool LevelMap::UpdateMap(); void LevelMap::ClearMap(); void LevelMap::UpdateScreen(); bool LevelMap::SetPosition(int AtX, int AtY); private: int MapX, MapY; int SizeX, SizeY; int ScreenX, ScreenY; char *Map; }; #endif /////////////////////////// //And Now the Cpp code: // /////////////////////////// #include "CPKMapClass.h" LevelMap::LevelMap(int map_x, int map_y, int screen_x, int screen_y) { SizeX = map_x; SizeY = map_y; ScreenX = screen_x; ScreenY = screen_y; CreateMap(); } LevelMap::LevelMap() { SizeX = 60; SizeY = 30; ScreenX = 11; ScreenY = 8; CreateMap(); } LevelMap::~LevelMap() { delete ScreenMap; delete Map; } char LevelMap::GetAbsoluteTile(int x, int y) { return Map[(x*ScreenY) + y]; } char LevelMap::GetTile(int x, int y) { return ScreenMap[(x*ScreenY) + y]; } bool LevelMap::CreateMap() { int MapSize; MapSize = SizeX*SizeY; Map = new char[MapSize]; MapX = 0; MapY = 0; MapSize = ScreenX*ScreenY; ScreenMap = new char[MapSize]; return true; } bool LevelMap::SetTile(int x, int y, char Value) { ScreenMap[(x*ScreenY) + y] = Value; return UpdateMap(); } bool LevelMap::UpdateMap() { return true; } void LevelMap::ClearMap() { char *MapPoint; MapPoint = Map; int i; for(i = 0; i <=SizeX*SizeY; i++) { *MapPoint = 55; MapPoint++; } } void LevelMap::UpdateScreen() { int i,j, indice; char Value; for(i = 0; i < ScreenX; i++) {for(j = 0; j < ScreenY; j++) { indice = (i + MapX)*SizeY + (j + MapY); Value = Map[indice]; indice = (i * ScreenY) + j; ScreenMap[indice] = Value; } } } bool LevelMap::SetPosition(int AtX, int AtY) { if(AtX <= (SizeX - ScreenX) && AtY <= (SizeY - ScreenY)) { MapX = AtX; MapY = AtY; return true; } else {MapX = 0; MapY = 0; return false; } } //////////////////////////////////////////////////////////////// // This is the part of the main that interacts with the class // //////////////////////////////////////////////////////////////// LevelMap CenMap(80, 40, 10, 8); // declared as global, not inside any function. int InitGL(GLvoid) //yes, it's a NeHe based { //(...) CenMap.ClearMap(); //(...) } int draw_tiles(GLvoid) { int tile; for (int y = 0; y < 9; y++) { for (int x = 0; x < 7; x++) { CenMap.UpdateScreen(); tile = CenMap.GetTile(x, y); if (tile != 0) { //(DrawStuff) } //(...) } PS. sorry about the lack of comments, but that's because they were not in English. Thanks! [edited by - algumacoisaqualquer on August 9, 2002 3:37:02 PM]

For Beginners

Started by algumacoisaqualquer August 09, 2002 02:28 PM

12 comments, last by algumacoisaqualquer 22 years, 4 months ago

Thunder_Hawk

314

August 09, 2002 03:45 PM

quote: Original post by algumacoisaqualquer
Thunder_Hawk - Well... Thanks!

dead_man_walking - sorry, but that didn''t made it, is getting the same error. I didn''t get the error with if (!ScreenMap){delete []ScreenMap;}, but I thinks this isn''t releasing any memory, so it is kind of pointless.

AP - I think that the problem is in the constructor, because it closed fine when I placed the delete part on coments, it has to be something there. i can post the code here, but i think it will be a little dificult to follow it, plus, I wasn''t geting any errors before using this class.

Thanks all you guys for the help!

First, please say that you are not using CreateMap anywhere outside of your constructors (its possible to fix it for that). Second, make sure you are not "delete"ing your pointers outside of your deconstructor (which I''m beginning to suspect). Third, I know its kind of nit-picky, but make sure you use delete like this:

"delete [] newed_array_pointer_name" or
"delete newed_pointer_name"

(notice the spacing around "[]")

Fourth, get used to this kind of problem... It happens quite often.

_____________________________

And the Phoenix shall rise from the ashes...

--Thunder_Hawk -- ¦þ
______________________________

______________________________________________________________________________________The Phoenix shall arise from the ashes... ThunderHawk -- ¦þ"So. Any n00bs need some pointers? I have a std::vector<n00b*> right here..." - ZahlmanMySite | Forum FAQ | File Formats______________________________________________________________________________________

algumacoisaqualquer

Author

170

August 09, 2002 04:04 PM

Well, it is working now, but about the CreateMap, it is only called by the constructors, so it is only called once. The delete part is never called, but it is the destructor so it is outomatic, and the arrays are only deleted there. About the delete part, Now I''m using if (ScreenMap){delete [] ScreenMap;}, but even if i made some changes, there was no error.

Well, sorry guys, but I should have left the computer about half-hour ago, so I''ll have to leave now.

Again, thanks for all the help.

python_regious

929

August 09, 2002 04:52 PM

What you people seem to be missing is that you can delete null pointers. Try doing this, it won''t crash:

  int main(){    int *ptr = 0;    delete ptr;    return 0;}

That is perfectly legal.

Death of one is a tragedy, death of a million is just a statistic.

If at first you don't succeed, redefine success.

Dobbs

164

August 10, 2002 09:13 PM

quote: Original post by dead_man_walking
and destructors are called automatically where you program ends, unless the class in declared with new.)

No, the destructor is called when they go out of scope.

And to back up python regious, deleting null pointers is valid C++ so there''s no real point in:

if (pointer) delete pointer;

delete will check if it''s null anyway, and if it''s not null that''s no guarantee that it''s safe to delete.

My First Class!!

This topic is closed to new replies.

Popular Topics

Recommended Tutorials

My First Class!!

This topic is closed to new replies.

Popular Topics

Recommended Tutorials

Reticulating splines