Date: Wed, 8 Jul 2020 13:41:49 +0200 From: Marko Turk <markoml@markoturk.info> To: rahul deshmukh <rahul.dshmkh1@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: strange output in c program Message-ID: <20200708114149.GA73229@vps.markoturk.info> In-Reply-To: <CAFa7P3fnvqCWfPJU-moJEyx0Wx=bL0sRjhMKLkyiBvN9k6ReSg@mail.gmail.com> References: <CAFa7P3fnvqCWfPJU-moJEyx0Wx=bL0sRjhMKLkyiBvN9k6ReSg@mail.gmail.com>
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On Wed, Jul 08, 2020 at 05:04:26PM +0530, rahul deshmukh wrote:
> Hi Team,
> i was learning c programming and came across a very strange output. kindly
> someone please guide me if i am missing anything.
>=20
> rdx@FreeBSD:~/Projects/Clang/chapter3 % uname -a
> FreeBSD FreeBSD 12.1-RELEASE FreeBSD 12.1-RELEASE r354233 GENERIC amd64
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> rdx@FreeBSD:~/Projects/Clang/chapter3 % cat example6.c
> #include <stdio.h>
> int main()
> {
> int a =3D 300, b, c;
> if(a >=3D 400)
> {
> printf("shouldn't print\n");
> b =3D 300;
> }
> c=3D200;
> printf("%d %d\n", b, c);
> return 0;
> }
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D
> rdx@FreeBSD:~/Projects/Clang/chapter3 % make example6
> `example6' is up to date.
> rdx@FreeBSD:~/Projects/Clang/chapter3 % ./example6
> 300 200=3D=3D> should be garbage value instead of 300?
The behaviour is undefined so anything can happen. Even different
optimization flags can change the value printed.
BR/Marko
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