Date: Thu, 04 Mar 2004 03:45:44 +1030 From: Wayne Sierke <ws+freebsd-questions@au.dyndns.ws> To: Dan Nelson <dnelson@allantgroup.com> Cc: freebsd-questions@freebsd.org Subject: Re: Size of variables in awk Message-ID: <1078334144.666.179.camel@ovirt.dyndns.ws> In-Reply-To: <20040303161840.GD79860@dan.emsphone.com> References: <1078286126.666.11.camel@ovirt.dyndns.ws> <20040303080359.GB79860@dan.emsphone.com> <1078304560.666.157.camel@ovirt.dyndns.ws> <20040303161840.GD79860@dan.emsphone.com>
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On Thu, 2004-03-04 at 02:48, Dan Nelson wrote:
> In the last episode (Mar 03), Wayne Sierke said:
> > On Wed, 2004-03-03 at 18:34, Dan Nelson wrote:
> > > In the last episode (Mar 03), Wayne Sierke said:
> > > > It seems I've run into the 32-bit signed number wall in awk
> > > > (5.2-RELEASE).
> > > >
> > > > My totals are maxing out at 2147483648.
> > > >
> > > > Would anyone happen to know whether that's really the case (that awk is
> > > > only implemented with 32-bit number capability - unfortunately I don't
> > > > have any other awks nearby to verify nor can I find any reference info
> > > > that indicates) and/or can suggest a way around it?
> > >
> > > Seems to works fine on -current:
> > >
> > > $ jot 8 30 | awk '{ print 2^$1 }'
> >
> > Ah, ok. Same for me on 5.2-RELEASE. More info:
> >
> > I'm using the printf function in awk but something ain't right:
> >
> > # jot 4 30 | awk '{ printf("%u\n", 2^$1-1) }'
> > 2147483648
> >
> > # jot 4 30 | awk '{ printf("%lu\n", 2^$1-1) }'
> > 2147483648
> >
> > # jot 4 30 | awk '{ printf("%llu\n", 2^$1-1) }'
> > 35186519572480
>
> I see nothing wrong here. %u is an unsigned int, and on x86 systems,
> an int is 32 bits. %llu is a long long unsigned int, and they are 64
> bits. Since there is no way for C to print a number larger than 64
> bits, you won't be able to use the numeric specifiers to print large
> numbers. You can use %s though. See
> /usr/src/contrib/one-true-awk/run.c, the format() function.
When you say "they are 64 bits" you're referring to a long
(signed/unsigned) int (not long long unsigned int)?
In which case aren't there two problems with the results shown?
1 - %u should print values up to 2^32-1
2 - %lu should print values up to 2^64-1
whereas they're both hitting a limit at 2^31.
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