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]

Re: Help With Copy Constructor.

I am calling the copy constructr like this:

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

In case this helps

[Phlip]

Re: Help With Copy Constructor.

JoeC wrote:
[color=blue]
> BYTE get(int n){return gdata[n];}[/color]

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]

Re: Help With Copy Constructor.


"JoeC" <enki034@yahoo. com> wrote in message
news:1146439853 .661368.187720@ g10g2000cwb.goo glegroups.com.. .[color=blue]
> 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.[/color]

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]

Re: Help With Copy Constructor.

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

[JoeC]

Re: Help With Copy Constructor.

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

[JoeC]

Re: Help With Copy Constructor.

Thanks now it looks like it is tarting to work.

[Ron Natalie]

Re: Help With Copy Constructor.

JoeC wrote:[color=blue]
> 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.[/color]

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]

Re: Help With Copy Constructor.

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]

Re: Help With Copy Constructor.

JoeC wrote:[color=blue]
> 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);
>[/color]

bitmap.bmBits = &gdata[0];

[JoeC]

Re: Help With Copy Constructor.

Thanks, I will have to redesign my whole class but I will give that a
try.

[JoeC]

Re: Help With Copy Constructor.

I tried what you sugested the program still crashes. What am I doing
wrong?

#include<window s.h>
#include<vector >
#include<iostre am>
#include<string >

using namespace std;

#ifndef GRAPHIC_H
#define GRAPHIC_H

class graphic{
int btmap;
int lr,ud; //Diminsion (size) of the graphic
vector<BYTE>gda ta;
HBITMAP hbitmap;
BITMAP bitmap;
HDC hdc, hdcmem;
void copy(const BYTE in[]);
BYTE get(int n)const {return gdata[n];}
vector<BYTE>vGe t() const {return gdata;}

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

#endif


#include<window s.h>
#include<fstrea m>
#include<string >
#include<vector >

#include "graphic.h"

using namespace std;

void graphic::copy(c onst BYTE in[]){
for(int lp=0; lp != 32; lp++)
gdata.push_back (in[lp]);
}

void graphic::SetGr( const BYTE c[]){
//Changing the graphic
copy(c);
BITMAP bitmap = {0,ud,lr,2,1,1} ;
bitmap.bmBits = &gdata[0];
hbitmap = CreateBitmapInd irect(&bitmap);
}

graphic::graphi c(const graphic& gr){
ud = lr = 16;
//memcpy( gdata, gr.gdata, 32 );
gdata = gr.vGet();

BITMAP bitmap = {0,ud,lr,2,1,1} ;
bitmap.bmBits = &gdata[0];
hbitmap = CreateBitmapInd irect(&bitmap);
}

[Dennis Jones]

Re: Help With Copy Constructor.


"JoeC" <enki034@yahoo. com> wrote in message
news:1146766337 .494189.227390@ u72g2000cwu.goo glegroups.com.. .[color=blue]
> I tried what you sugested the program still crashes. What am I doing
> wrong?[/color]

You will need to be more specific -- "still crashes" doesn't tell us
anything. What is crashing and where?

- Dennis

[JoeC]

Re: Help With Copy Constructor.

I am experimenting with different ways to do what I want. It is
tricky. I want the graphics data to be held in the objects on a grid
of space objects. That works. But what I want to do is to have
objects stored in those objects with graphic data and I want that that
data to be displayed on the screen. I got the program to run like I
would like but it the program is not written to be expanded. I want to
have variouse kinds of objects that contain graphics data later and I
don't want to keep updating my board object with new data. That is how
I made it work, I put the graphics data for my player on the map with
all the graphics for the map.

class board{

player * play;
static const int size = 30;
map<char, coord> keys;
space spaces[size][size];
coord n;
coord s;
coord e;
coord w;

ifstream& cfill(ifstream& , char&); /*Reads map from file */
void fill();
coord find();
void seeing(int, int);

public:
board();
void setPlayer(playe r*, int, int);
graphic& display(int, int);
int sze(){return size;}
void move(char);
};

There might or might not be a player in the map so I use a pointer. I
wand the graphics data from that player to be returned to the main
program for display.

graphic& space::graphicO ut(){
if(play){
BYTE * cr = &play->GetData();
cgr = new graphic(cr);
//&play->GetData());
return *cgr; //I want to get the player's graphic data either the
bitmap array or
the graphic object and return it for display.
}
if(seen){return *gr;} //returns the graphic on the map (space or
wall)
else {return *grDefault;} //returns unseen space (blank)
}

This is the trick of what I am trying to do.

[Dennis Jones]

Re: Help With Copy Constructor.


"JoeC" <enki034@yahoo. com> wrote in message
news:1146968129 .282597.300520@ v46g2000cwv.goo glegroups.com.. .

<irrelevant content snipped>

I thought you wanted help with a crash, so I asked how and where your
program was crashing. You didn't answer that question and now you seem to
be talking about something else. Was there supposed to be a question
somewhere in that last message?

- Dennis