Thread: three dimenssional arrays

Can somebody please tell me how do I use three dimenssional arrays. eg char ***array

A simple example using a dynamic 3D array:

Code:

#include <stdio.h>

const int a = 10;
const int b = 4;
const int c = 100;

int main(void)
{
   int i, j;
   char ***array;

   /* allocate memory */
   array = (char ***) malloc(a * sizeof(*array));

   for(i = 0; i < a; i++)
   {
      array[i] = (char **)malloc(b * sizeof(**array));
      for(j = 0; j < b; j++)
         array[i][j] = (char *)malloc(c * sizeof(***array));
   }

   /* fill array */
   for(i = 0; i < a; i++)
      for(j = 0; j < b; j++)
         sprintf(array[i][j], "%d - %d", i, j);

   /* print array */
   for(i = 0; i < a; i++)
      for(j = 0; j < b; j++)
         printf("%s\n", array[i][j]);

   /* free memory */
   for(i = 0; i < a; i++)
   {
      for(j = 0; j < b; j++)
         free((void *)array[i][j]);
      free((void *)array[i]);
   }

   free((void *)array);

   return 0;
}

If you are asking because you say code that has a char ***array in it then I should point out that this is probably not a three dimensional array. You'll usually see this when one needs a pointer to a 2d array or a pointer to a pointer to an array. Using a char *** as a parameter in a function which allocates memory for a char ** is not uncommon.

Code:

void ArrayAlloc(char ***array, int width, int height) {
    int w;
    *array = (char **array)malloc(height*sizeof(char *));
    for(;--height;)
        (*array)[height] = (char *)malloc(width);
}

int main(void) {
    char **array;
    ArrayAlloc(&array, 20, 20);
    return 0;
}