C error “variable-sized object may not be initialized” [duplicate]

Answer 1

Your two arrays are variable lenght arrays. You cannot initialize a variable length array in C.

To set all the int elements of your arrays to 0 you can use the memset function:

memset(plansza, 0, sizeof plansza);

By the way to initialize an array which is not a variable length array, the valid form to initialize all the elements to 0 is:

int array[31][14] = {{0}};  // you need the {}

Answer 2

Alternative to the suggestion of @Chris:

You can create 2d array as an array of one-dimensional arrays. This will allow you to do array element indexing as you used to. Be aware that in this case array is allocated in heap, not in stack. Therefore, when you don't need the array anymore, you must clean the allocated memory.

Example:

#include <malloc.h>
#include <string.h>

/* Create dynamic 2-d array of size x*y.  */
int** create_array (int x, int y)
{
  int i;
  int** arr = (int**) malloc(sizeof (int*) * x);
  for (i = 0; i < x; i++)
    {
      arr[i] = (int*) malloc (sizeof (int) * y);
      memset (arr[i], 0, sizeof (arr[i]));
    }
  return arr;
}

/* Deallocate memory.  */
void remove_array (int** arr, int x)
{
  int i;
  for (i = 0; i < x; i++)
    free (arr[i]);
  free (arr);
}

int main()
{
  int x = 5, y = 10;
  int i, j;
  int** plansza = create_array (x, y); /* Array creation.  */
  plansza[1][1] = 42; /* Array usage.  */
  remove_array (plansza, x); /* Array deallocation.  */
  return 0;
}

Answer 3

If both dimensions are unknown, you'll have to use a one-dimensional array, and do the indexing yourself:

int *ary = (int *) malloc(x * y * sizeof(int));
memset(ary, 0, x * y * sizeof(int));
int elem1_2 = ary[1 * x + 2];
int elem3_4 = ary[3 * x + 4];

and so on. You better define some macros or access functions. And free the memory after use.