UNIX for Advanced & Expert Users

the version is
(cc -V)

cpp.ansi: HP92453-01 B.11.11.20 HP C Preprocessor (ANSI)
ccom: HP92453-01 B.11.11.20 HP C Compiler

HPUx...

(uname -r)
B.11.23

which means it should be HP-UX 11i v2

the output being displayed is

./test

0

(as it is extern variable)

"extern" means "don't allocate any memory for this variable -- assume it already exists". Except it doesn't -- you've never actually defined it anywhere -- so the assumption ends up being wrong. When the linker looks for it, it can't find it.

HP's linker really ought to complain, too. A linker's not supposed to just invent nonexistent variables for you. I can imagine that causing really weird bugs someday.

Here's how it's supposed to work:

Code:

$ cat myextern.c

#include "myextern.h"

// This actually defines the contents of the variable.
// This is what actually makes the variable exist.
int myextern=3;

$ cat myextern.h

#ifndef __MYEXTERN_H__
#define __MYEXTERN_H__

extern int myextern;

#endif/*__MYEXTERN_H__*/

$ cat uses-extern.c

#include <stdio.h>
#include "myextern.h"

int main(void)
{
        printf("myextern = %d\n", myextern);
        return(0);
}

$

I totally agree that what I am trying to do in the code in HPUx is completely illogical.
That's why I was expecting the error during the executable formation in HPUx also.

But I was surprised by what actually happened over there.
So I was just wondering if there is any difference in the handling for symbols in both linkers or possibly just a loose checking (/bug) on HPUx side.

Actually, according to Niklas Wirth, it isn't: "routine" is a collective term for "procedures" and "functions". "Function" being a routine with exactly one return value, whereas "procedure" is a routine with no return value at all.

C blurs this difference by treating everything as a function, but PASCAL and similar languages don't. The closest analogon to a "procedure" in C would be a function defined to return "void".

bakunin

You are right bakunin i got confused between routine and subroutine...

---------- Post updated at 01:24 PM ---------- Previous update was at 01:21 PM ----------

I think that the version of your C compiler is very old so you should get a new one or install gcc which is free of cost...
Can you post the output of "uname -a" on your hpux system...

here is what uname -a gives


HP-UX srv_name B.11.23 U 9000/800 srv_name unlimited-user license