File pointer reading in c and returning null if EOF

Question

I am a student making a function that takes an file pointer, lets say stdin and returns a struct pointer. So I'm not sure how to begin. It should return a null pointer when EOF is encountered.

This is what I made so far:

typedef struct book
{
    char *author;
    char *title;
    char *bookcode;
} Book;

Book *getBook(FILE *pointer)
{
    Book *p;
    int c;
    while ((c = fgetc(pointer)) != EOF)
    {
     //create book
      putchar (c);
    }
    }
    return p;
}

example of input file

chris evans
hello there
as2 ss1
ashley lee
big buildings
d2a 4sa

Please elaborate your question and tell us what you are actually trying to achieve. We need a larger picture of your problem. Also read [this](http://xyproblem.info/) and [this](http://stackoverflow.com/help/how-to-ask). And learn how to format code. What is `Book`? What does your file contain ? — Jabberwocky, Oct 14 '16 at 09:58
Re your edit, please see [Why is “while ( !feof (file) )” always wrong?](http://stackoverflow.com/questions/5431941/why-is-while-feof-file-always-wrong) — Weather Vane, Oct 14 '16 at 10:07
What is the format of the file ?? Give us an example of that file containing say 2 books. — Jabberwocky, Oct 14 '16 at 10:08
Are you familiar with pointer and the concept of dynamic memory allocation ? If no, get familiar with that first. — Jabberwocky, Oct 14 '16 at 10:12
Use `fgets` to read in text. Remember each string input will have a `newline` at its end which you will have to remove. — Weather Vane, Oct 14 '16 at 10:34

Jabberwocky · Answer 1 · 2016-10-14T11:53:38.353

You roughly need this:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct book
{
  char *author;
  char *title;
  char *bookcode;
} Book;

void freeBook(Book *p)
{
  free(p->author);
  free(p->title);
  free(p->bookcode);
  free(p);
}

Book *getBook(FILE *pointer)
{
  Book *p = malloc(sizeof(Book));
  p->author = NULL;
  p->title = NULL;
  p->bookcode = NULL;

  char line[200];

  if (fgets(line, sizeof(line), pointer) != NULL)
    p->author = strdup(line);

  if (fgets(line, sizeof(line), pointer) != NULL)
    p->title = strdup(line);

  if (fgets(line, sizeof(line), pointer) != NULL)
    p->bookcode = strdup(line);

  if (feof(pointer))
  {
    freeBook(p);
    return NULL;
  }
  else
    return p;
}

int main()
{
  Book *pBook;

  do
  {
    pBook = getBook(stdin);

    // do something with pBook


   freeBook(pBook);   // free memory of book if you are done with it
                      // and only if you are done with it.  
  } while (pBook != NULL);
}

Disclaimer:

This is basic, non error checking code and there is still much room for improvement, it's just to give you an idea.

Thanks a lot but how do you skip the first book once the function is called so the second book will be returned like in the example input file — Jon, Oct 14 '16 at 16:07

File pointer reading in c and returning null if EOF

1 Answers1