dynamic 2d struct arrays? (newbie)

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Neuro Fuzzy

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Joined: 11th Jun 2007

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Posted: 18th Feb 2009 04:02

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I want to create a dynamic array with 2 dimensions. I could do it like:
int map[(yheight*xwidth]
to get an array the same size as map[xwidth][yheight]

but can i use a struct, on a dynamic array, with 2 dimensions?

err, it's not "Gimm3 teh codez" or anything, but if you could add in declaring map[mapsize][mapsize] to my code below, that'd help alot.

+ Code Snippet



struct map_struct
{
   int style ;
   int kind;
   int rot;
};
int mapsize;


#include "DarkGDK.h"

// the main entry point for the application is this function
void DarkGDK ( void )
{
	int x;
	int y;
	int mapsize;

	mapsize=dbVal(dbInput());
	map_struct * map;
	map = new map_struct [mapsize];

	for(x=0; x<mapsize; x++)
	{

			map[x].style=dbRND(10);
			map[x].kind=dbRND(10);
			map[x].rot=dbRND(10);

	}

	dbPrint(dbStr(map[2].style));
	dbWait(10000);
	// return back to windows
	return;
}

all i get when i run it is a black screen

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prasoc

15

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Posted: 18th Feb 2009 10:39

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You arn't setting "mapsize" to any number. I am not sure about the array of structs, but it might be "map_struct map[mapsize];"

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Diggsey

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Joined: 24th Apr 2006

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Posted: 18th Feb 2009 13:38

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You can't declare a dynamic array like that.

If it is to hold a map, and you are only going to resize it between levels, then the best way is to do this:

+ Code Snippet

map_struct* map = NULL;
int map_width;
int map_height;

void AllocateMap(int width, int height)
{
    // If map already exists, delete it
    if (map)
        delete[] map;

    map_width = width;
    map_height = height;
    map = new map_struct[width*height];
}
map_struct& GetItem(int x, int y)
{
    return map[y*map_width+x];
}

Use GetItem(x,y) to access an item in the array, and use AllocateMap(width,height) to create the map, and then to resize it.

Because GetItem returns a reference, you can assign to it too:
GetItem(0,0) = map_struct();

[b]Yuor signutare was aresed by a deslyxic mud...
BOX2D V2 HAS HELP FILES! AND A WIKI!

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prasoc

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Posted: 18th Feb 2009 17:28

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You learn something new every day

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Hayer

18

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Joined: 4th Nov 2005

Location: Norway

Posted: 18th Feb 2009 22:49

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and you dont need to declare "x".
U could simply type

+ Code Snippet

for([b]int[/b] x=0; x < 100; ++x)
{
// Code
}

Keep it simple.
Questions? Mail me

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Neuro Fuzzy

17

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Joined: 11th Jun 2007

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Posted: 19th Feb 2009 01:10

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eh, oh well. i guess it's not that much of a difference between typing
map[10][10]
and
map[mapindex(10,10)]

thanks.

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Dark GDK / dynamic 2d struct arrays? (newbie)