dynamically allocate an **pointer in a struct

Question

I'm trying to learn how to allocate a 2d array within a struct, but it keeps getting a segfault. I know how to allocate a 2d array outside of a struct but i don't know why its getting a segfault when i move it into a struct.

/*program to allocate a 2d array and fill it with 0's and then print it.*/
#include<stdio.h>
#include<stdlib.h>

typedef struct stuff
{
   int **arr;
}stuff;

int main()
{
  stuff x;
  int i,j;//loop counters
  //allocate 2d array
  x.arr = (int**)malloc(sizeof(int*)*4);
  for(i=0; i<4; i++)
    x.arr[i] = (int*)malloc(sizeof(int)*4);
//intialize 2d array to 0
  for (i = 0; i < 4; i++)
     for (j = 0; j < 4; j++)
       x.arr[i][j] = 0;
//print 2d array
  for(i=0; i<4; i++);
    for(j=0; j< 4; j++)
       printf("arr[%d][%d] = %d \n", i ,j ,x.arr[i][j]);
  return 0;
}

Answer 1

You have an extra semicolon in your last i loop. This causes you access wrong memory address, as j loop runs with i value of 4, which is out of bounds.

Answer 2

Change for(i=0; i<4; i++); into for(i=0; i<4; i++) and everything works well