From: Segher Boessenkool <segher@koffie.nl>
To: Nicholas Strauss <nicks@carriage.chesco.com>
Cc: gcc-help@gcc.gnu.org, Nicholas Strauss <ncs@alum.mit.edu>
Subject: Re: unsigned long long int with os-x
Date: Sun, 13 Oct 2002 17:06:00 -0000 [thread overview]
Message-ID: <3DAA0A1A.CAEECF78@koffie.nl> (raw)
In-Reply-To: <9E647882-DEBB-11D6-BFB0-000393AC01F6@carriage.chesco.com>
Nicholas Strauss wrote:
>
> Hi,
>
> I'm trying to use gcc in darwin os-x. I've written the following piece of code:
>
> int main(int argc, char *argv[])
> {
> unsigned long long int u;
>
> u = 1<<63;
This is the int 1 shifted by 63 bits to the left; that's "undefined behaviour"
by the C standard (and will probably result in 0).
Write
u = 1LL << 63;
instead.
> printf("u: %ld uu: %ld\n", u, u-1);
> printf("maxint %ld\n", INT64_MAX);
> }
>
> What compiler/linker options should I use with gcc?
No special options are needed. But try out -Wall and -W.
> What format should I use with printf?
"%lld" if I remember correctly.
Have fun,
Segher
next prev parent reply other threads:[~2002-10-14 0:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-13 7:59 Nicholas Strauss
2002-10-13 17:06 ` Segher Boessenkool [this message]
2002-10-13 17:11 ` Nicholas Strauss
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