In article <5bauu7$b55@mulga.cs.mu.OZ.AU>
           fjh@mundook.cs.mu.OZ.AU "Fergus Henderson" writes:

>"David R. Tribble" <david.tribble@central.beasys.com> writes:
>
>>(BTW, this brings up a few questions about POSIX data types.
>>Specifically, how big are uid_t, gid_t, pid_t, off_t, et al?  If I have
>>to print them, do I use "%d" or "%ld"?  This is not a problem on 32-bit
>>systems, but it can be on 64-bit CPUs.  Personally, I always cast them to
>>long and use "%ld".)
>
>That used to be the correct way to do it in C -- but changes to the C
>standard, specifically the introduction of a "long long" data type --
>mean that this long-standing idiom may break.

Yes, it may but only when the values being printed exceed the range of
a long. I suspect that it won't break the vast majority of code. I'm
not suggesting that it isn't a problem however.

> Instead, the best way to
>do it in C is probably to cast to cast to type `longest', defined by
>
>        #ifdef HAVE_LONG_LONG
>        typedef long long longest;
>        #else
>        typedef long longest;
>        #endif
>
>where HAVE_LONG_LONG must be determined using autoconf or similar
>techniques.

The code also has to select a suitable printf conversion specifier. That's
possible bit makes printf code messy.

>Of course the way to do it in C++ is much simpler: just use
>`cout << x;'.

--
-----------------------------------------
Lawrence Kirby | fred@genesis.demon.co.uk
Wilts, England | 70734.126@compuserve.com
-----------------------------------------



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"David R. Tribble" <david.tribble@central.beasys.com> writes:

>(BTW, this brings up a few questions about POSIX data types.
>Specifically, how big are uid_t, gid_t, pid_t, off_t, et al?  If I have
>to print them, do I use "%d" or "%ld"?  This is not a problem on 32-bit
>systems, but it can be on 64-bit CPUs.  Personally, I always cast them to
>long and use "%ld".)

That used to be the correct way to do it in C -- but changes to the C
standard, specifically the introduction of a "long long" data type --
mean that this long-standing idiom may break.  Instead, the best way to
do it in C is probably to cast to cast to type `longest', defined by

 #ifdef HAVE_LONG_LONG
 typedef long long longest;
 #else
 typedef long longest;
 #endif

where HAVE_LONG_LONG must be determined using autoconf or similar
techniques.

Of course the way to do it in C++ is much simpler: just use
`cout << x;'.

(This article is crossposted, so please be careful with follow-ups.)

--
Fergus Henderson <fjh@cs.mu.oz.au>   |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>   |  of excellence is a lethal habit"
PGP: finger fjh@128.250.37.3         |     -- the last words of T. S. Garp.
---
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