static or non static

[Szabolcs Nagy]

this is probably only a stylistic question

what do you think to be better in a single .c file program, declaring
functions with static qualifier or without it?

eg:
#include <stdio.c>
static int add(int a, int b) {return a+b;}
int main() {
printf("1+2=%d\ n", add(1, 2));
return 0;
}

is there any difference between the two?

static int add(..)
or
int add(..)

[jacob navia]

Re: static or non static

Szabolcs Nagy wrote:

this is probably only a stylistic question
>
what do you think to be better in a single .c file program, declaring
functions with static qualifier or without it?
>
eg:
#include <stdio.c>
static int add(int a, int b) {return a+b;}
int main() {
printf("1+2=%d\ n", add(1, 2));
return 0;
}
>
is there any difference between the two?
>
static int add(..)
or
int add(..)
>

Always use static for functions that are not referenced outside the
module in which they are defined. This helps to keep name conflicts low.

Note that function names are exported by default in C.

Besides,

If a function is not used and it is declared static, the compiler
will warn you. If it is not, the compiler can't know if it is used in
another module and you end up with many functions unused completely
taking place for nothing at all.

[Ben Pfaff]

Re: static or non static

Szabolcs Nagy <nszabolcs@gmai l.comwrites:

what do you think to be better in a single .c file program, declaring
functions with static qualifier or without it?

I would generally use static. Single-file programs tend to grow,
and it's easier if they're done "properly" from the start.
--
"To get the best out of this book, I strongly recommend that you read it."
--Richard Heathfield

[Richard]

Re: static or non static

Szabolcs Nagy <nszabolcs@gmai l.comwrites:

this is probably only a stylistic question
>
what do you think to be better in a single .c file program, declaring
functions with static qualifier or without it?
>
eg:
#include <stdio.c>
static int add(int a, int b) {return a+b;}
int main() {
printf("1+2=%d\ n", add(1, 2));
return 0;
}
>
is there any difference between the two?
>
static int add(..)
or
int add(..)

In theory I would recommend marking them all as static. In practice,
well, I tend to keep a specific "extern" header for others to include
since more functions than not are often used outside of the file they
are defined in.

[CBFalconer]

Re: static or non static

Szabolcs Nagy wrote:

>
what do you think to be better in a single .c file program,
declaring functions with static qualifier or without it?
>
eg:
#include <stdio.c>
static int add(int a, int b) {return a+b;}
int main() {
printf("1+2=%d\ n", add(1, 2));
return 0;
}
>
is there any difference between the two?
>
static int add(..)
or
int add(..)

The advantage of the 'static' is that you can later decide to
expand the system with a separate file, and not worry about the
fact that 'add' has already been defined. static makes it only
visible within the original file.

Using add() in an external C file requires all of 1. removal of the
static and 2. inclusion of a prototype in main.h, and 3. #include
"main.h" in the new file.

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>



--
Posted via a free Usenet account from http://www.teranews.com

[Eric Sosman]

Re: static or non static

Szabolcs Nagy wrote:

this is probably only a stylistic question
>
what do you think to be better in a single .c file program, declaring
functions with static qualifier or without it?
>
eg:
#include <stdio.c>

Unusual header name ...

static int add(int a, int b) {return a+b;}
int main() {
printf("1+2=%d\ n", add(1, 2));
return 0;
}
>
is there any difference between the two?
>
static int add(..)
or
int add(..)

Use `static', even in single-module programs. Even if
the program never grows beyond a single file, the fact that
the compiler can "see" all the calls to add() may allow the
compiler to optimize it more aggressively, for example, by
compiling it in-line.

--
Eric Sosman
esosman@ieee-dot-org.invalid

[Szabolcs Nagy]

Re: static or non static


Eric Sosman wrote:

Szabolcs Nagy wrote:

static int add(..)
or
int add(..)

>
Use `static', even in single-module programs. Even if
the program never grows beyond a single file, the fact that
the compiler can "see" all the calls to add() may allow the
compiler to optimize it more aggressively, for example, by
compiling it in-line.

thank you all the answers
i guess static is nicer solution then

but can it really matter with respect to the optimization?
may be the .o code contains the extern functions but what about the
executable?
i thought in situations like this (single-module program) the compiler
automatically handles every function as static in the final
executable.


as a final note:
i checked the src of traditional unix tools (which are mostly single-
modul programs) and found both conventions to be used (static and
extern functions)
also note that c-faq contains very little amount of information about
'static' (i'm not complaining i just expected more questions)

[Szabolcs Nagy]

Re: static or non static


Eric Sosman wrote:

[snip]

thanks your comment was very helpful