Can't find the BUG

This is a part of a code i wrote, i BOLD-marked the problem,
an anyone fine it?

Code:

index = ((id%MAX_BORROW_SIZE)*(sizeof(
brw_movie)));
   
    fseek(fp_borrowed, index, SEEK_SET);
    fread(&temp, sizeof(brw_movie), 1, fp_borrowed);
   
    if (temp.ordered == 1)
    {
        temp.ordered = 0;
        fseek(fp_borrowed, index, SEEK_SET);

        //temp.catalog_id = 0;
        fwrite(&temp, sizeof(brw_movie), 1, fp_borrowed);
        printf("Movie id# %d has been deleted from Borrowed Movies.\n", id);

        // **************** CHECK *************** //

        fseek(fp_borrowed, index, SEEK_SET);
        fread(&temp, sizeof(brw_movie), 1, fp_borrowed);
        printf(" --> %d\n", temp.ordered);

OUTPUT -->

What is the movie catalog no#? 22
Your fine is: 75.000000 due to lag of 15 days!
Movie id# 22 has been deleted from Borrowed Movies.
--> 1
The movie was already ordered by another customer (# 2).

Tried flushing the file after writing and before reading?
Oh and do use code tags.

Originally Posted by Elysia

Tried flushing the file after writing and before reading?
Oh and do use code tags.

Flushing should not be necessary - the filesystem should be consistent in that sense.

One suggestion (as I can't see anything directly wrong with the code itself) it would probably be a good idea to check the results from fseek, fread and fwrite. If you get errors, check that the file is opened in "r+" mode, perhaps?

--
Mats

I would have suggested fflush(), but fseek() seems good

Originally Posted by c99 on fopen

When a file is opened with update mode (’+’ as the second or third character in the
above list of mode argument values), both input and output may be performed on the
associated stream. However, output shall not be directly followed by input without an
intervening call to the fflush function or to a file positioning function (fseek,
fsetpos, or rewind), and input shall not be directly followed by output without an
intervening call to a file positioning function, unless the input operation encounters endof-
file. Opening (or creating) a text file with update mode may instead open (or create) a
binary stream in some implementations.

The next step is definitely improving the error checking.

Originally Posted by matsp

Flushing should not be necessary - the filesystem should be consistent in that sense.

I looked at msdn, but couldn't find any guarantees of fseek flushing the stream before seeking. But then again, MSDN is not known to be the best source.