[OPEN-ILS-DEV] C nits: invalid conversion specification

[Mike Rylander]

I (or Bill) will be fixing this in HEAD later today, which will put it
in line for 1.2 as soon as that happens.  Opinions on the criticality
of backporting to the 1.0 branch?

--miker

On 5/7/07, Joe Atzberger <atzberger at mecdc.org> wrote:
> Perl accepts it inasmuch as it doesn't consider it an error (even under warnings and strict).  The typical error message
> would be (for example, with %j):
>         Invalid conversion in printf: "%j"
>
> I agree there doesn't seem to be any reason to use "%lf" in perl either, since apparently all floating point formatting
> gets handed off to the C sprintf.
>
> --Joe
>
> Scott McKellar wrote:
> > What is your basis for saying that Perl accepts "%lf" for printf
> > and sprintf?
> >
> > I looked at the link you provided, and I looked in the camel book
> > (which has much of the same verbiage), and I don't see any indication
> > that "%lf" is valid in Perl.
> >
> > Given that Perl relies on the C library to format floating point
> > numbers, one of three things must be happening:
> >
> > 1. Perl silently removes the extraneous 'l' before passing the
> > conversion specification to the C library, or:
> >
> > 2. It doesn't, and whatever happens happens, depending on what the
> > C library does on a give platform, or:
> >
> > 3. It issues an error or warning message, and possibly takes either
> > of the above actions as well.
> >
> > I just experimented with a test script using "%lf" and perl didn't
> > complain, even with the -w option.  So the third possibility above
> > appears not to be happening.
> >
> > In any case, it seems like there's no good reason to use "%lf" in
> > Perl, any more than in C.
> >
> > Disclaimer: my knowledge of Perl doesn't extend much beyond how to
> > spell it.
> >
> > Scott McKellar
> > http://home.swbell.net/mck9/aargh/
> >
> >
> > --- Joe Atzberger <atzberger at MECDC.ORG> wrote:
> >
> >> Perl accepts "%lf" as an accepted format for printf and sprintf.  It
> >> would only be particularly meaningful on a system
> >> where the default size of a floating point number was not long double
> >> (i.e., double or quad).
> >>
> >>  From perldoc:
> >>      http://perldoc.perl.org/functions/sprintf.html
> >>    "For floating point conversions (e f g E F G), numbers are usually
> >> assumed to be the default floating point size on
> >> your platform (double or long double), but you can force 'long
> >> double' with q, L , or ll if your platform supports them."
> >>
> >> Interestingly, this may conflict with the fact that perl's sprintf
> >> actually invokes the C version for floating point
> >> numbers:
> >>    "Perl does its own sprintf formatting--it emulates the C function
> >> sprintf, but it doesn't use it (*except for
> >> floating-point numbers*, and even then only the standard modifiers
> >> are allowed)."
> >>
> >> So based on that, I'm more confused than anything.  It seems like it
> >> should only be a question of what the C version
> >> supports for floats, even if perl doesn't report a warning/error.
> >>
> >> --Joe Atzberger
> >> INFOhio Technical Specialist
> >> Metropolitan Educational Council
> >> (614) 473-8300 x22
> >> atzberger at mecdc.org
> >
> > <snip>
>
>


-- 
Mike Rylander