Memory allocation

#include <stdio.h>
#include <stdlib.h> /* required for the malloc and free functions */

int main() {
  int number;
  int *ptr;
  int i;

  printf("How many ints would you like store? ");
  scanf("%d", &number);

  ptr = malloc(number*sizeof(int)); /* allocate memory */


  if(ptr!=NULL) {
    for(i=0 ; i<number ; i++) {
      *(ptr+i) = i;
    }

    for(i=number ; i>0 ; i--) {
      printf("%d\n", *(ptr+(i-1))); /* print out in reverse order */
    }

    free(ptr); /* free allocated memory */
    return 0;
  }
  else {
    printf("\nMemory allocation failed - not enough memory.\n");
    return 1;
  }
}