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Re: Missing warning about uninitialized variable.
- From: "J.C. Pizarro" <jcpiza at gmail dot com>
- To: "Mikael Vidstedt" <mikael dot vidstedt at bea dot com>, gcc-help at gcc dot gnu dot org
- Date: Thu, 29 Nov 2007 16:48:49 +0100
- Subject: Re: Missing warning about uninitialized variable.
On 2007/11/29, Mikael Vidstedt <mikael.vidstedt@bea.com> wrote:
> The following program may make use of an uninitialized variable (gurka):
>
> int
> main(int argc, char* argv[])
> {
> int gurka;
>
> if(argc == 10) {
> gurka = 3;
> }
>
> // gurka isn't necessarily initialized here...
> printf("%d\n", gurka);
>
> return 0;
> }
>
> GCC 4.0 will give a warning when this program is compiled with "-O
> -Wall". GCC 4.1 and 4.2 do not give that warning. I haven't had the
> possibility to try GCC 4.3.
>
> What say ye?
>
> Thanks,
> Mikael
It prints stochasticly random data too.
gcc version 4.2.3 20071031 (prerelease)
$ gcc -Wall -o foo foo.c
foo.c: In function 'main':
foo.c:11: warning: implicit declaration of function 'printf'
foo.c:11: warning: incompatible implicit declaration of built-in
function 'printf'
$ for i in $(seq 1 5); do ./foo $(seq 1 10) ; done
-1209020420
-1208291332
-1208422404
-1208803332
-1208823812
$
J.C.Pizarro