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Date: Sun, 5 Jun 2011 21:06:43 +0200
From: Jilles Tjoelker <jilles@stack.nl>
To: "Sean C. Farley" <scf@FreeBSD.org>
Message-ID: <20110605190643.GA62966@stack.nl>
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	<alpine.BSF.2.02.1106051426190.9196@thor.farley.org>
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Cc: hackers@FreeBSD.org, Ben Laurie <ben@links.org>
Subject: Re: int64_t and printf
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On Sun, Jun 05, 2011 at 02:31:27PM -0400, Sean C. Farley wrote:
> On Sun, 5 Jun 2011, Ben Laurie wrote:
> > So, for example int64_t has no printf modifier I am aware of. Likewise 
> > its many friends.

> > In the past I've handled this by having a define somewhere along the 
> > lines of...

> > #if <something>
> > # define INT_64_T_FMT "%ld"
> > #else
> > # define INT_64_T_FMT "%lld"
> > #endif

> > but I have no idea where to put such a thing in FreeBSD. Opinions? 
> > Also, I guess I'd really need to do a modifier rather than a format, 
> > for full generality.

> You need to include inttypes.h, which includes machine/_inttypes.h. 
> This will provide the appropriate macro which in this case is PRId64.

The macros from <inttypes.h> are certainly valid, but the style in most
of FreeBSD prefers casting to a type such as intmax_t or uintmax_t for
which a constant format string is available (%jd/%ju). In the particular
case of int64_t, it would seem that long long is better than intmax_t,
as it is possibly shorter but still guaranteed large enough by C99, but
there are objections against this that I do not understand.

Also, note the format strings for size_t, %zu, and for ptrdiff_t, %td.

-- 
Jilles Tjoelker