Problem with pointers, getting seg fault while indexing with variable instead of plain number

Question

I would like to ask why is that giving me seg fault.

  int **a = (int**) malloc (sizeof(int*) * 3);
  a[0][0] = 1;
  a[0][1] = 2;
  a[0][2] = 3;

  for(int i = 0; i < 3; i++)
  {
      printf("%d", a[0][i]);
      //but works with for instance: a[0][1]
  }

Answer 1

You are allocating memory for three pointers to int, but those are uninitialised, point to random places, not to memory to store actual ints in.

Either have mallocs for those pointers, too, or use statically sized arrays instead of pointers to int.