Dynamic Memory Allocation in C using malloc()

#include <stdio.h>
#include <conio.h>
//#include <malloc.h> OR
#include <stdlib.h>
void main()
{
    int *ptr, i, n, sum = 0;
    printf("how many elements ? ");
        scanf("%d", &n);
    ptr = (int *)malloc(n * sizeof(int));   

  if (ptr == NULL)
    printf("\n Memory not allocated.\n");
  else
  {
    printf("\nEnter the elements : \n");
      for (i=0; i<n; i++)
      {
        scanf("%d", (ptr+i));
        sum += *(ptr + i);        // sum will calculate the summation of n numbers
      }
printf("\n\nSum = %d, and elements : ", sum);
for (i=0; i<n; i++)
    printf("\n %d", *(ptr + i));
}

free(ptr);   //deallocates the memory previously allocated by a call to malloc()

printf("\n\nSum = %d, and elements : ", sum);
  for (i = 0; i<n; i++)
    printf("\n\n %d", *(ptr + i));    // it will print garbage values as we have deallocated the memory                                                            // using free() call
getch();
}