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I have following code .
#include<stdio.h>
int i;
int i;
int i;

int main()
{
printf("%d",i);
return 0;
}

It compiles fine .

now i modify above code to

#include<stdio.h>
int i = 0;
int i;
int i;

int main()
{
printf("%d",i);
return 0;
}

again it compiles fine.

now i introduce more change to above code

#include<stdio.h>
int i = 0;
int i = 0;
int i;

int main()
{
printf("%d",i);
return 0;
}

It gives me redefination Error.

Ok it means that statement 'int i;' is just a declaration. I guess, it
is not just a declaration since our very first code(code with all 'int
i;') compiled with no error. There exists atleast one defination of
'i'. what should we say to statement 'int i;' ?

shaanxxx said:

> I have following code .
> #include<stdio.h>
> int i;

Tentative definition.

> int i;

Tentative definition.

> int i;

Tentative definition.

Why three?

> It compiles fine .

Yes, - but... why?

> now i modify above code to
>
> #include<stdio.h>
> int i = 0;

Definition and initialisation.

> int i;

Tentative definition.

> int i;

Tentative definition.

But... *why*?

>
> int main()
> {
> printf("%d",i);
> return 0;
> }
>
> again it compiles fine.
>
> now i introduce more change to above code
>
> #include<stdio.h>
> int i = 0;

Definition and initialisation.

> int i = 0;

Definition and initialisation. That's two for-sure definitions with the same
name, which is a for-sure error. And it has to be asked... WHY?

> int i;

Tentative definition.

> int main()
> {
> printf("%d",i);
> return 0;
> }
>
> It gives me redefination Error.
>
> Ok it means that statement 'int i;' is just a declaration. I guess, it
> is not just a declaration since our very first code(code with all 'int
> i;') compiled with no error. There exists atleast one defination of
> 'i'. what should we say to statement 'int i;' ?

"Don't do it" is the obvious answer, surely?

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at above domain (but drop the www, obviously)

"shaanxxx" <> wrote in message
news: oups.com...
>I have following code .
> #include<stdio.h>
> int i;
> int i;


My compilers all say:
error: redeclaration of 'i'

> int i;
>
> int main()
> {
> printf("%d",i);
> return 0;
> }
>
> It compiles fine .
><snip>

Get a new compiler
--
Fred L. Kleinschmidt
Boeing Associate Technical Fellow
Technical Architect, Software Reuse Project

Fred Kleinschmidt wrote:
> "shaanxxx" <> wrote in message
> news: oups.com...
> >I have following code .
> > #include<stdio.h>
> > int i;
> > int i;
>
> My compilers all say:
> error: redeclaration of 'i'

Your compilers are all non-conforming, then.

Fred Kleinschmidt schrieb:
> "shaanxxx" <> wrote
>
>>I have following code .
>>#include<stdio.h>
>>int i;
>>int i;
>
> My compilers all say:
> error: redeclaration of 'i'

Then all your compilers are wrong.

>>int i;
>>
>>int main()
>>{
>>printf("%d",i);
>>return 0;
>>}
>>
>>It compiles fine .
>><snip>
>
> Get a new compiler

Maybe you got confused with the difference between declarations
with file scope and linkage and with block scope and no linkage:
,---
#include<stdio.h>
int i;
int i;

int main (void)
{
extern int j;
int j = 10;
int k;
int k = 10;
printf("%d\n",i);
printf("%d\n",j);
printf("%d\n",k);
return 0;
}

`---
$ gcc -std=c89 -pedantic -Wall -O tentative.c -c
tentative.c: In function `main':
tentative.c:10: error: redeclaration of 'k' with no linkage
tentative.c:9: error: previous declaration of 'k' was here
tentative.c:9: warning: unused variable `k'


Cheers
Michael
--
E-Mail: Mine is an /at/ gmx /dot/ de address.

Fred Kleinschmidt wrote:
> "shaanxxx" <> wrote in message
> news: oups.com...
>> I have following code .
>> #include<stdio.h>
>> int i;
>> int i;
>
>
> My compilers all say:
> error: redeclaration of 'i'

You are posting to <news:comp.lang.c>. You are using compilers for a
different language, probably C++, which has a newsgroup of its own,
<news:comp.lang.c++>. Perhaps you should learn to use "My compilers all."

"Martin Ambuhl" <> wrote in message
news:...
> Fred Kleinschmidt wrote:
>> "shaanxxx" <> wrote in message
>> news: oups.com...
>>> I have following code .
>>> #include<stdio.h>
>>> int i;
>>> int i;
>>
>>
>> My compilers all say:
>> error: redeclaration of 'i'
>
> You are posting to <news:comp.lang.c>. You are using compilers for a
> different language, probably C++, which has a newsgroup of its own,
> <news:comp.lang.c++>. Perhaps you should learn to use "My compilers all."

I am using:
gcc on CYGWIN on a PC
/opt/ansic/bin/cc on HP 11.11
/usr/ibmcc/bin/xlc on AIX 5.3
/usr/bin/cc on IRIX 6.5
gcc on SunOS5.8
--
Fred L. Kleinschmidt

Fred Kleinschmidt wrote:
> "Martin Ambuhl" <> wrote in message
> news:...
>> Fred Kleinschmidt wrote:
>>> "shaanxxx" <> wrote in message
>>> news: oups.com...
>>>> I have following code .
>>>> #include<stdio.h>
>>>> int i;
>>>> int i;
>>>
>>> My compilers all say:
>>> error: redeclaration of 'i'
>> You are posting to <news:comp.lang.c>. You are using compilers for a
>> different language, probably C++, which has a newsgroup of its own,
>> <news:comp.lang.c++>. Perhaps you should learn to use "My compilers all."
>
> I am using:
> gcc on CYGWIN on a PC
> /opt/ansic/bin/cc on HP 11.11
> /usr/ibmcc/bin/xlc on AIX 5.3
> /usr/bin/cc on IRIX 6.5
> gcc on SunOS5.8

You are invoking it as a C++ compiler. When GCC is invoked as a C
compiler, it does not give the diagnostic you report. Please learn to
use "My compilers all" or post your C++ observations to
<news:comp.lang.c++>, not <news:comp.lang.c>.

Richard Heathfield wrote:
> shaanxxx said:
>
>> I have following code .
>> #include<stdio.h>
>> int i;
>
> Tentative definition.
>
>> int i;
>
> Tentative definition.
>
>> int i;
>
> Tentative definition.
>
> Why three?
>
>> It compiles fine .
>
> Yes, - but... why?
>
>> now i modify above code to
>>
>> #include<stdio.h>
>> int i = 0;
>
> Definition and initialisation.
>
>> int i;
>
> Tentative definition.
>
>> int i;
>
> Tentative definition.
>
> But... *why*?
>
>> int main()
>> {
>> printf("%d",i);
>> return 0;
>> }
>>
>> again it compiles fine.
>>
>> now i introduce more change to above code
>>
>> #include<stdio.h>
>> int i = 0;
>
> Definition and initialisation.
>
>> int i = 0;
>
> Definition and initialisation. That's two for-sure definitions with the same
> name, which is a for-sure error. And it has to be asked... WHY?
>
>> int i;
>
> Tentative definition.
>
>> int main()
>> {
>> printf("%d",i);
>> return 0;
>> }
>>
>> It gives me redefination Error.
>>
>> Ok it means that statement 'int i;' is just a declaration. I guess, it
>> is not just a declaration since our very first code(code with all 'int
>> i;') compiled with no error. There exists atleast one defination of
>> 'i'. what should we say to statement 'int i;' ?
>
> "Don't do it" is the obvious answer, surely?
>
The OP correctly distilled the case of his predicament to a minimum.
That's a satisfactory answer to "why".
[I am sure Mr. Heathfield does not question the general utility of
tentative definitions <OT> unfortunately removed from C++ </OT>.]
- Ark

Ark said:

<snip>

> [I am sure Mr. Heathfield does not question the general utility of
> tentative definitions

I don't? Why on earth not?

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at above domain (but drop the www, obviously)