C99 doesn't allow local scope variables?

C99 doesn't allow local scope variables?

[tabris]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

simple C program

#include <stdlib.h>
#include <stdio.h>

int main(void)
{
    for (int i=0; i < 2; i++)
        printf("crap\n");
};

[tabris@tabriel tmp]$ gcc test.c -o test
test.c: In function `main':
test.c:6: error: `for' loop initial declaration used outside C99 mode

What does that mean, and why am I not allowed to make a local scope variable 
for a for{;;} loop?

works fine if i declare the variable outside the loop. But I swear I used to 
do this with gcc 2.95.
- --
tabris
- -
Body by Nautilus, Brain by Mattel.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.3 (GNU/Linux)

iD8DBQFAFc1J1U5ZaPMbKQcRAiJyAJ4namXjJa9zd6Y/VGbR+Y5pyHVjUwCcCy4s
dW251Zxh2o3I97eabiisOMg=
=21yl
-----END PGP SIGNATURE-----

Re: C99 doesn't allow local scope variables?

[wwp]

Hello tabris,


On Mon, 26 Jan 2004 21:30:30 -0500 tabris <tabris@tabris.net> wrote:

[snip]
> [tabris@tabriel tmp]$ gcc test.c -o test
> test.c: In function `main':
> test.c:6: error: `for' loop initial declaration used outside C99 mode
> 
> What does that mean, and why am I not allowed to make a local scope variable
> 
> for a for{;;} loop?
> 
> works fine if i declare the variable outside the loop. But I swear I used to
> 
> do this with gcc 2.95.

ANSI C89 requires int i; to be declared outside from the for(), only ANSI C99
and C++ allow this, IIRC.


Regards,

-- 
wwp

Re: C99 doesn't allow local scope variables?

[Glynn Clements]

tabris wrote:

> simple C program
> 
> #include <stdlib.h>
> #include <stdio.h>
> 
> int main(void)
> {
>     for (int i=0; i < 2; i++)
>         printf("crap\n");
> };
> 
> [tabris@tabriel tmp]$ gcc test.c -o test
> test.c: In function `main':
> test.c:6: error: `for' loop initial declaration used outside C99 mode

You are trying to use C99 syntax in a file which isn't being treated
as such.

The default C dialect is C89 plus GNU extensions (-std=gnu89). The
Info file for gcc 3.0 says that C99 plus GNU extensions (-std=gnu99)
will become the default once the C99 support is complete. Until then,
if you want to use C99, you have to explicitly ask for it with
-std=c99 or -std=gnu99.

See the "C Dialect Options" node in the gcc Info file for more
details.

> What does that mean, and why am I not allowed to make a local scope variable 
> for a for{;;} loop?
> 
> works fine if i declare the variable outside the loop. But I swear I used to 
> do this with gcc 2.95.

You may have been using a modified version of gcc, although I suppose
that it's possible that -std=gnu99 may have been the default for some
versions.

-- 
Glynn Clements <glynn.clements@virgin.net>