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From: "Jake" <LightningRider AT 1st DOT net>
Newsgroups: comp.lang.c,comp.os.msdos.djgpp
Subject: Pointer Blues
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Date: Mon, 21 Jan 2002 05:36:57 GMT
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

Pointers are begining to drive me crazy.
Ok here's the problem, I needed two 2 dimensional arrays that are visual to
all
the functions. So I defined two 'pointer-to-pointer' varibles of type int,
thats what 2 dimensional arrays really are, 'pointers-to-pointer' right?
That problem is the that whatever value I asign to one array shows up in the
array, I can have have this.
If someone can follow the code and know whats going on please help me out.

      thanks
       Jake
#include <stdio.h>
int columns = 8;
int rows = 8;
int **map;
int **mask;
void initarray(int **arr);  // allocates memory
void display(int **arr);
int main(int argc, char *argv[])
{
  int x,y;
  initarray(map);
  initarray(mask);
  for ( y = 0; y < rows;y++)
    for (x=0;x<columns;x++){
      map[x][y] = x;
      mask[x][y] =x*2;
    }
  display(map);
  display(mask);
  return 0;
}

void display(int **arr)
{
 int x,y;
 for (y=0; y<rows; y++){
   for (x=0; x < columns; x++)
     printf("%3d",arr[x][y]);
   puts("");
 }
 puts("");
}

void initarray(int **arr)
{
 int x;
  for (x=0;x<columns;x++)
    arr[x] = (int *)calloc(rows, sizeof(int));
}