I have a structure 'map'. In it I have two variable, width and height. I want to create a two dimensional array of integers, with the subscripts of width and height. So I would write:
int data[width][height]

Would this work? Another thing is the values of width and height are not know until after creating an instance of map. So would this code work?

struct map{
int height, width;
int data[width][height];
};

struct map castle;

map.height = 20;
map.width = 30;

If code like this would not work, which I am pretty sure it won't. What are my options for having similar functioning code? Basicly I want a structure that has an array of integers, where the subscript can be decided after it's declaration.

Thanks, JoshG.

I think you should first dreate a 1x1 2 dimensiolan array, and then malloc afterwards. I dunno if it'd work, but that's the first idea that pops up inside me now
[addsig]

Below is a quick and dirty approach:


struct map {
int height, width;
int * data;
};

struct map create (int height, int width) {
struct map ret;
ret.height=height; ret.width=width;
data = calloc(sizeof(int), height*width);
}

int read (struct map * a, int h, int w) {
return (data[(a--->width)*h+j]);
}

void write (struct map * a, int h, int w, int val) {
data[(a--->width)*h+j] = val;
}


Useful?




[ This Message was edited by: seunosewa on 2002-03-31 17:57 ]

no, because it isn't what he wants to do.
[addsig]

Well, if he's particular about the syntax and not just the functionality, Creating a 1x1 dimensional array, and mallocing afterwards, would not work. This may work:


////////////////////bfcode
struct map {
int height, width;
int ** data;
};

map createmap (int w, int h) {
map ret;
ret.height=h; ret.width=w;
ret.data = (int **)malloc(i);
for (int k=0; kw; k++) {
free((void *)m--->data[k]);
}
free ((void *)m--->data); m--->data=NULL;
}
////////////////////afcode


I cannot test it now, though.

[ This Message was edited by: seunosewa on 2002-04-01 20:29 ]

I dont know what you really want to do. If you want the user to enter information and then store it in the array using malloc() then use linked list. Go here and download http://cslibrary.stanford.edu/ the pdf if you dont know what a linked list is.

Or go and read my ol' crappy tutorial on the topic [addsig]

you should have a pointer to a pointer then allocate memory for it. the other approach would be C++ and STL ....

using a vector would also be useful in this case
(caution: not the maths/physics vector )
[addsig]

Yep. The STL Vector should do fine. [addsig]

btw, what does "STL" stand for anyways?
[addsig]

Standard Template Library

A collection of very useful templates.
[addsig]

ahhh, ok, I'll keep that in my head
[addsig]