Global variable conflict.

[Shinu George]

I have two files like given below:

/* File 1 */
#include <stdio.h>
#include <stdlib.h>

void tf(void);

int i;

int main(void)
{
i = 10;
tf();

return EXIT_SUCCESS;
}

/* End File 1 */

/* File 2 */
#include <stdio.h>

int i = 48;


void tf(void)
{
printf("%d\n", i);
}


/* End File 2 */


The observed behaviour is that the "printf" always prints the value of i as 10.

Two questions:

1 (for clc). Is the above code standards (ANSI) compliant?
2 (for cup). How do I get the linker to "see" the i with value 48 on Solaris?

Thanks and regards,
Shinu

[Emmanuel Delahaye]

In 'comp.lang.c', [email]supercool_libran@yahoo.co.uk[/email] (Shinu George) wrote:

> I have two files like given below:
>
> /* File 1 */
> #include <stdio.h>
> #include <stdlib.h>
>
> void tf(void);
>
> int i;
>
> int main(void)
> {
> i = 10;
> tf();
>
> return EXIT_SUCCESS;
> }
>
> /* End File 1 */
>
> /* File 2 */
> #include <stdio.h>
>
> int i = 48;

You can't have two global scope variables with the same name in the same
project. Your linker should warn you about that.

> void tf(void)
> {
> printf("%d\n", i);
> }
>
>
> /* End File 2 */
>
>
> The observed behaviour is that the "printf" always prints the value of i
> as 10.

Won't link at home.

> Two questions:
>
> 1 (for clc). Is the above code standards (ANSI) compliant?

No.

If you insist to have these global scope variables, you must reduce their
scope to the file with 'static'.

--
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The C-language FAQ: [url]http://www.eskimo.com/~scs/C-faq/top.html[/url]
<blank line>
FAQ de f.c.l.c : [url]http://www.isty-info.uvsq.fr/~rumeau/fclc/[/url]

[E. Robert Tisdale]

Shinu George wrote:

[snip]

> cat file2.h

#ifndef GUARD_FILE2_H
#define GUARD_FILE2_H 1
#include <stdio.h>
#include "file2.h"

extern int i;

void tf(void);

#endif//GUARD_FILE2_H

> cat file2.c

/* File 2 */
#include "file2.h"

int i = 48;

void tf(void) {
printf("%d\n", i);
}

/* End File 2 */

> cat file1.c

/* File 1 */
#include "file2.h"
#include <stdlib.h>

int main(int argc, char* argv[]) {
tf();
i = 10;
tf();

return EXIT_SUCCESS;
}

/* End File 1 */

> gcc -Wall -std=c99 -pedantic -O2 -o file file1.c file2.c
> ./file

48
10