«

i have done a test like this with gcc3.4.2:
int main(){

for(int i =0;i<3;i++);

return 0;
}
if i complile my code without using -std=c99,it shows a message :'for'
loop initial declaration used outside C99 mode .
i wonder that if not use -std=c99,which std it compile with?how can i
find that out?
(if i use -std=c99,it's ok)

"" <> writes:
> i wonder that if not use -std=c99, which std it compile with? how
> can i find that out?

GNU C, which can be more or less accurately described as C89 with
extensions.

The problem with declarations in the initialization part of a for loop
is that GCC had a similar feature with slightly different semantics
before it was standardized. Code that relies on those semantics will
either not compile or produce different results with -std=c99, so the
GCC maintainers have decided to deprecate the old extension.

DES
--
Dag-Erling Smørgrav -

Dag-Erling Smørgrav wrote:
> "" <> writes:
>
>>i wonder that if not use -std=c99, which std it compile with? how
>>can i find that out?
>
>
> GNU C, which can be more or less accurately described as C89 with
> extensions.
>
The full story can be found in the GCC manual:
http://gcc.gnu.org/onlinedocs/gcc-3....ialect-Options

S.

"" <> writes:
> i have done a test like this with gcc3.4.2:
> int main(){
>
> for(int i =0;i<3;i++);
>
> return 0;
> }
> if i complile my code without using -std=c99,it shows a message :'for'
> loop initial declaration used outside C99 mode .
> i wonder that if not use -std=c99,which std it compile with?how can i
> find that out?
> (if i use -std=c99,it's ok)

That's a question about gcc, not about the C language. You'll find
the answer in the extensive documentation that's provided with gcc.

--
Keith Thompson (The_Other_Keith) kst- <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.