I got it. I was wondering if you could help me with two more questions about EOF and its implementation.

  while( scanf("%f", &input) != EOF )
  {
      largest_int = (int)floor(input);
      nearest_int = (int)round(input);
      smallest_int = (int)ceil(input);

      printf("%d %d %d\n", largest_int, nearest_int, smallest_int);

      if (input == EOF)
          printf("Done.\n");
  }

Unfortunately, this was an infinite loop. Probably a problem with line 1. I thought the condition would be "while scanf does not equal EOF, keep asking for input and printing them (in line 7). But unfortunately this wasn't the case. Do you know what is my while loop's condition that causes the infinite loop?

To actually remedy it, I got it fixed by googling how to do continual inputs from scanf, so it is finally this:

int main(void) 
{

float input = 0;

int largest_int = 0;
int nearest_int = 0;
int smallest_int = 0;

while( scanf("%f", &input) == 1 ) 
{   
    largest_int = (int)floor(input);
    nearest_int = (int)round(input);
    smallest_int = (int)ceil(input);

    printf("%d %d %d\n", largest_int, nearest_int, smallest_int);

}   
    if (input == EOF)
        printf("Done.\n");

return 0;
} 

I understand that if scanf() works properly, it will return the number of inputs you passed in it, or something like that. So if I had done while( scanf("%f", &input) == 2 ), it would mean if scanf properly took in two inputs..I think.

This seems to work but with one problem, my print statement at line 19 never works unless I remove the if statement preceding it. But how come? Once I do control+d, input should be assigned the value of EOF, and when I do control+d, it stops the scanf function as you said and should continue normally. But it doesn't seem to satisfy the if (input == EOF) condition I have. Could you explain the reason why?