C program to find the number of elements in an array

Write a C program to find the number of elements in an array.

  #include <stdio.h>

  int main() {
        int arr[] = {10, 20, 30, 40, 50};
        int val1, val2, size, num;

        /*
         * fetching the address of first and
         * second element in the given array
         */
        val2 = (int)&arr[1];
        val1 = (int)&arr[0];

        /* size of an element in the given array */
        size = val2 - val1;

        /*
         * number of elements equals total size of
         * the array divided by size of an element
         * in the given input array
         */
        num = sizeof(arr) / size;

        /* print the number of elements in the given array */
        printf("Number of elements in the given array is %d\n", num);

        return 0;
  }

  Output:

  jp@jp-VirtualBox:~/$ ./a.out
  Number of elements in the given array is 5