int64_t and printf
Jilles Tjoelker
jilles at stack.nl
Sun Jun 5 19:06:45 UTC 2011
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
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