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/* Playing with realloc(). Store user input in an array */
/* Don't forget to add the .h to the header file(s)! */
#include <stdio>
#include <stdlib>

#define INITIAL_SIZE 5;

int main()
{
   int *Arr, *temp;
   int limit, input, n = 0, r, i;

   /* Initially, allocate some space for Arr */
   limit = INITIAL_SIZE;
   Arr = (int *) malloc (limit * sizeof(int));
   printf("The allocated memory is sizeof(limit * sizeof(int)) = %d bytes\n", sizeof(limit * sizeof(int)));
   printf("Or sizeof(Arr) = %d bytes\n", sizeof(Arr));
   
   /* Do some verification, if fail */
   if (Arr == NULL)
      {
         /* Display the error message */
         fprintf(stderr, "malloc() failed!\n");
         /* Exit with the error code */
         exit(1);
         }
   /* array loop */
   printf("Enter numbers, 1 per line. End with ctrl-D\n");
   while(1)
      {
         printf("Next number: ");
         /* r = scanf("%d", &input); */
         r = scanf_s("%d", &input, sizeof(input));
         fflush(stdin);
         /* verify the input */
         if(r <1>= limit)
            {
               printf("More than 5 elements per loop, reallocating the storage... \n");
               limit = 2 * limit;
               temp = (int *)realloc(Arr, limit * sizeof(int));
               printf("The added memory storage is %d bytes\n", sizeof(temp));
               /* Verify again... */
               if(temp == NULL)
                  {
                     fprintf(stderr, "realloc() failed!\n");
                     exit(1);
                     }
               else
                  printf("realloc() is OK lol, proceed with more input...\n");
               Arr = temp;
               }
         Arr[n] = input;
         n++;
         }
   /* Trim Arr down to size */
   temp = (int *)realloc(Arr, n*sizeof(int));
   /* Verify... */
   if(temp == NULL)
      {
         fprintf(stderr, "realloc() fails lol!\n");
         exit(1);
         }
   Arr = temp;
   printf("\nContents of the array Arr:\n");
   /* Print the array */
   for(i = 0; i < n; i++)
      {
         printf("%2d ", Arr[i]);
         }
   printf("\n");
   return 0;
}

The allocated memory is sizeof(limit * sizeof(int)) = 4 bytes
Or sizeof(Arr) = 4 bytes
Enter numbers, 1 per line. End with ctrl-D
Next number: 12
Next number: 23
Next number: 34
Next number: 45
Next number: 56
Next number: 67
More than 5 elements per loop, reallocating the storage...
The added memory storage is 4 bytes
realloc() is OK lol, proceed with more input...
Next number: 98
Next number: 87
Next number: 76
Next number: 65
Next number: 54
More than 5 elements per loop, reallocating the storage...
The added memory storage is 4 bytes
realloc() is OK lol, proceed with more input...
Next number: ^D

Contents of the array Arr:
12 23 34 45 56 67 98 87 76 65 54
Press any key to continue . . .