Help With Copy Constructor.

[JoeC]

I am still working on my game and my program is getting better. Most
of what I want to works. I think I am having trouble with copy
constructor. Basically I want it to copy the gdata array. My gdata
will work if I do: gdata[32] = this->get(lp); But that is not what I
want to do I get some cryptic errors when I write the code like that is
commented out.

49 C:\Documents and Settings\Work\M y Documents\C++\D ungeon
Adventure2\gaph ic.cpp passing `const graphic' as `this' argument of
`BYTE graphic::get(in t)' discards qualifiers

C:\Documents and Settings\Work\M y Documents\C++\D ungeon
Adventure2\Make file.win [Build Error] [gaphic.o] Error 1

I am pretty good with pointer and objects but my compiler is fustrating
me. Can I get some advice to make this copy constructer do what it is
suppoded to do.

class graphic{
int btmap;
int lr,ud; //Diminsion (size) of the graphic
BYTE gdata[32]; //bitmap array
HBITMAP hbitmap;
BITMAP bitmap;
HDC hdc, hdcmem;
void copy(BYTE in[]);
BYTE get(int n){return gdata[n];}

public:
graphic();
graphic(BYTE c[]);
graphic(const graphic&);
graphic& operator = (graphic&);
void SetGr(BYTE c[]);
void set(BYTE c[]);
void display(HWND, int, int);
};

graphic::graphi c(const graphic& gr){
for(int lp = 0; lp != 32; lp++){
//gdata[32] = gr.get(lp); <- I get errors.
}
ud = lr = 16;
BITMAP bitmap = {0,ud,lr,2,1,1} ;
bitmap.bmBits = gdata;
hbitmap = CreateBitmapInd irect(&bitmap);
}

[JoeC]

I am calling the copy constructr like this:

if(play){
cgr = new graphic(play->gOut());
return *cgr;
}

In case this helps

[Phlip]

JoeC wrote:

BYTE get(int n){return gdata[n];}

BYTE get(int n) const {return gdata[n];}

Now Google for "const correct". You should make constant any method that
doesn't change *this.

--
Phlip
http://c2.com/cgi/wiki?ZeekLand <-- NOT a blog!!!

[Dennis Jones]

"JoeC" <en*****@yahoo. com> wrote in message
news:11******** **************@ g10g2000cwb.goo glegroups.com.. .

I am still working on my game and my program is getting better. Most
of what I want to works. I think I am having trouble with copy
constructor. Basically I want it to copy the gdata array. My gdata
will work if I do: gdata[32] = this->get(lp); But that is not what I
want to do I get some cryptic errors when I write the code like that is
commented out.

It seems to me that the easiest and most straight-forward way to copy the
contents of gdata is to simply do this:

graphic::graphi c(const graphic& gr)
{
memcpy( gdata, gr.gdata, sizeof(BYTE) * sizeof(gdata) );
}

- Dennis

[JoeC]

OK that is a start I took out some consts because I was getting errors.
Thanks.

[JoeC]

OK, that helped, but it seems like my graphics data is not getting
coppied.

[JoeC]

Thanks now it looks like it is tarting to work.

[Ron Natalie]

JoeC wrote:

I am still working on my game and my program is getting better. Most
of what I want to works. I think I am having trouble with copy
constructor. Basically I want it to copy the gdata array. My gdata
will work if I do: gdata[32] = this->get(lp); But that is not what I
want to do I get some cryptic errors when I write the code like that is
commented out.

49 C:\Documents and Settings\Work\M y Documents\C++\D ungeon
Adventure2\gaph ic.cpp passing `const graphic' as `this' argument of
`BYTE graphic::get(in t)' discards qualifiers

C:\Documents and Settings\Work\M y Documents\C++\D ungeon
Adventure2\Make file.win [Build Error] [gaphic.o] Error 1

I am pretty good with pointer and objects but my compiler is fustrating
me. Can I get some advice to make this copy constructer do what it is
suppoded to do.

class graphic{
int btmap;
int lr,ud; //Diminsion (size) of the graphic
BYTE gdata[32]; //bitmap array
HBITMAP hbitmap;
BITMAP bitmap;
HDC hdc, hdcmem;
void copy(BYTE in[]);
BYTE get(int n){return gdata[n];}

public:
graphic();
graphic(BYTE c[]);
graphic(const graphic&);
graphic& operator = (graphic&);
void SetGr(BYTE c[]);
void set(BYTE c[]);
void display(HWND, int, int);
};

graphic::graphi c(const graphic& gr){
for(int lp = 0; lp != 32; lp++){
//gdata[32] = gr.get(lp); <- I get errors.

gdata[lp] = gr.get(lp);

I suspect you don't need the get() fucntion here, if all it returns is
gdata[lp] because gr.gdata while private is accessible here.

gdata[lp] = gr.gdata[lp];

You could avoid a lot of silliness by not using the busted
C++ array type and use vector which has proper copy semantics.

I assume eventually, you'll want to get rid of the assumptions
that ud and lr are both 16.

[JoeC]

I would like to use a vector but all this dosn't seem to accept a
vector when I did some earlier experiments. I would much rather use a
standard libray.

BITMAP bitmap = {0,ud,lr,2,1,1} ;
bitmap.bmBits = gdata; <- onc etried a vector here and it didn't
work.
hbitmap = CreateBitmapInd irect(&bitmap);

[Ron Natalie]

JoeC wrote:

I would like to use a vector but all this dosn't seem to accept a
vector when I did some earlier experiments. I would much rather use a
standard libray.

BITMAP bitmap = {0,ud,lr,2,1,1} ;
bitmap.bmBits = gdata; <- onc etried a vector here and it didn't
work.
hbitmap = CreateBitmapInd irect(&bitmap);

bitmap.bmBits = &gdata[0];