> According to my manpage, printf returns 0 on success, 1 on failure. No > mention of the number of characters written. This is different with > sprintf/snprintf (see e.g > http://www.opengroup.org/onlinepubs/000095399/functions/snprintf.html), > but IIRC a number of platforms don't implement those according to the > standard anyway.
According to the page you cite, printf and fprintf "shall return the number of bytes transmitted". When Olivier first suggested this, my original thought was the same as yours because I remembered the huge mess in the VAX days with sprintf (does it return int or char *?), but I've looked at lots of man pages (including ancient ones) and can't find anything that says anything else about the return of printf. > I suppose that the most portable way to achieve what you want here is > to write to a temporary string, then compare the lengths of the > temporary strings... Agreed. > Or just add a call to _set_printf_count_output in the relevant > place, since AFAIK %n is still a standard-mandated printf format > flag. Where is the "relevant place"? This would be a really messy host-dependent call and I think it far better to eliminate the usage in *some* way than to do this.
