Re: Question regarding fwrite() and fflush()

On Tue, 25 Jun 2024 13:55:47 -0700, Tim Rentsch wrote:

Lew Pitcher <lew.pitcher@digitalfreehold.ca> writes:
 

In a recent reply here, I posted some code that used fwrite() to write
binary data to a file.  One version of this code used mmap() to access
this binary data in-situ, and I wonder if I should have called fflush()
before calling mmap().
>
I understand the where to use fflush() on standard text formatted output
(where you use fprintf(), etc to externalize the output), but I don't see
anything my copies of either the ISO C or POSIX standards that say that
I /should/ use fflush(), but neither do I see anything that says I /need
not/ use fflush().
>
So, wiser and more experienced minds, should I use fflush() in this case
or not?

 
Yes, do use fflush().

As I suspected.
Now, my code includes an fflush() after all the fwrite()s are complete.
 

In the alternative, do a setbuf( file, 0 ) so that 'file' is
unbuffered.

Thanks
--
Lew Pitcher
"In Skills We Trust"