Is there a real need to use keyword static with functions?

[lcdgoncalves@gmail.com]

Hi everyone

Is there a real need to use keyword static with functions, if we
simply don't declare their prototypes in .h file?

Many textbooks avoid to discuss this matter and/or discuss only the
usage of static functions. I've been programming for years and I never
felt a real need for the "static approach for functions".

I don't know if this is a trivial matter since the reserved word
exists. :)
Or it exists for some other purpose I can't figure out.

What did I have missed? :)

Thanks in advance for answers

[Ian Collins]

Re: Is there a real need to use keyword static with functions?

lcdgoncalves@gm ail.com wrote:

Hi everyone
>
Is there a real need to use keyword static with functions, if we
simply don't declare their prototypes in .h file?
>

Yes, otherwise the functions have global scope and pollute the global
namespace. You may not want to export those symbols and you, or the
user of you code, will run into link problems if the same name is used
in more than one source file.

--
Ian Collins.

[christian.bau]

Re: Is there a real need to use keyword static with functions?

On Mar 5, 9:10 pm, lcdgoncal...@gm ail.com wrote:

Many textbooks avoid to discuss this matter and/or discuss only the
usage of static functions. I've been programming for years and I never
felt a real need for the "static approach for functions".

That's sad.

Do you have a database of all functions in your programs to make sure
that you don't use the same function name twice?

[Ben Pfaff]

Re: Is there a real need to use keyword static with functions?

lcdgoncalves@gm ail.com writes:

Is there a real need to use keyword static with functions, if we
simply don't declare their prototypes in .h file?

Yes. If two functions are defined without static, but with the
same name, in different translation units, then the result is
undefined behavior. Using static avoids this undefined behavior.
--
"C has its problems, but a language designed from scratch would have some too,
and we know C's problems."
--Bjarne Stroustrup

[Kenny McCormack]

Re: Is there a real need to use keyword static with functions?

In article <87649fl71z.fsf @blp.benpfaff.o rg>,
Ben Pfaff <blp@cs.stanfor d.eduwrote:

>lcdgoncalves@g mail.com writes:
>

>Is there a real need to use keyword static with functions, if we
>simply don't declare their prototypes in .h file?

>
>Yes. If two functions are defined without static, but with the
>same name, in different translation units, then the result is
>undefined behavior. Using static avoids this undefined behavior.

Again, you guys are "talking around the problem". What you should be
reacting to is the implication (i.e., the OP's delusion) that neglecting
to declare a prototype in a header file somehow "hides" global symbols
found in translation units. I.e., makes it as if they had been declared
(gasp!) static.

Well, to the OP, 'taint so.

[user923005]

Re: Is there a real need to use keyword static with functions?

On Mar 5, 1:10 pm, lcdgoncal...@gm ail.com wrote:

Hi everyone
>
Is there a real need to use keyword static with functions, if we
simply don't declare their prototypes in .h file?
>
Many textbooks avoid to discuss this matter and/or discuss only the
usage of static functions. I've been programming for years and I never
felt a real need for the "static approach for functions".
>
I don't know if this is a trivial matter since the reserved word
exists. :)
Or it exists for some other purpose I can't figure out.
>
What did I have missed? :)
>
Thanks in advance for answers

Functions should always be made static if they are not intended as end-
user available routines.
Imagine some function called :
void HelperInitializ er(struct goombah * foo);
and it is only supposed to be called by *you* the programmer. It is
to be called only once and if it were to be called again, it would
reset the state of some of your objects in a way not intended. It is
essential to define this function as static or it *will* be available
to the end-user of the library whether you like it or not.

There are lots of other sensible reasons for static (some of which are
mentioned else-thread).

The author of that book wouldn't have been Herbert Schildt, would it?

[Richard Tobin]

Re: Is there a real need to use keyword static with functions?

In article <1173129046.926 414.36190@c51g2 000cwc.googlegr oups.com>,
<lcdgoncalves@g mail.comwrote:

>Is there a real need to use keyword static with functions, if we
>simply don't declare their prototypes in .h file?

Bear in mind that there's nothing magic about .h files. They're just
some C code - usually, but not necessarily declarations - that can be
handily included in other files. So the fact that a function isn't
declared in a .h file doesn't stop some other part of the program from
using it, or from inadvertently using the same name for something else
(which may be detected when you link the program, or may just cause
some peculiar failure later on).

-- Richard
--
"Considerat ion shall be given to the need for as many as 32 characters
in some alphabets" - X3.4, 1963.

[Erik de Castro Lopo]

Re: Is there a real need to use keyword static with functions?

lcdgoncalves@gm ail.com wrote:

Hi everyone
>
Is there a real need to use keyword static with functions, if we
simply don't declare their prototypes in .h file?

Not necessary, but good practice.

If you use static then you can have two C files which both have
their own definition of my_function and the compiler will accept
it and do the right thing.

If you don't use static you will get a link time error about two
definitions of my_function.

HTH,
Erik
--
+-----------------------------------------------------------+
Erik de Castro Lopo
+-----------------------------------------------------------+
Failure is not an option. It comes bundled with your Microsoft
product.

[pradeep]

Re: Is there a real need to use keyword static with functions?

Hi everyone,
Is there any real need for keyword "static inline" with
functions.

--pradeep.
On Mar 6, 3:59 am, Erik de Castro Lopo <e...@mega-nerd.comwrote:

lcdgoncal...@gm ail.com wrote:

Hi everyone

>

Is there a real need to use keyword static with functions, if we
simply don't declare their prototypes in .h file?

>
Not necessary, but good practice.
>
If you use static then you can have two C files which both have
their own definition of my_function and the compiler will accept
it and do the right thing.
>
If you don't use static you will get a link time error about two
definitions of my_function.
>
HTH,
Erik
--
+-----------------------------------------------------------+
Erik de Castro Lopo
+-----------------------------------------------------------+
Failure is not an option. It comes bundled with your Microsoft
product.

[santosh]

Re: Is there a real need to use keyword static with functions?

pradeep wrote:

Please don't top-post. Your reply should be below or interspersed with
the material you quote. Irrelevant text can be deleted, particularly
sig blocks that follow a '-- ' marker.
[fixed]

On Mar 6, 3:59 am, Erik de Castro Lopo <e...@mega-nerd.comwrote:

lcdgoncal...@gm ail.com wrote:

Hi everyone

Is there a real need to use keyword static with functions, if we
simply don't declare their prototypes in .h file?

Not necessary, but good practice.

If you use static then you can have two C files which both have
their own definition of my_function and the compiler will accept
it and do the right thing.

If you don't use static you will get a link time error about two
definitions of my_function.

Hi everyone,
Is there any real need for keyword "static inline" with
functions.

Well, static's effect has been explained in this thread. The inline
qualifier is a hint to the compiler to speed up access to the
function, if possible. Generally, it's used for very small functions
that're called in tight loops. The compiler may or may not actually
embed the function's body into each place where it's invoked. There
may be other methods of speeding up access to it.

inline is a C99 feature, unlike static.

[santosh]

Re: Is there a real need to use keyword static with functions?


pradeep wrote:

Hi everyone,
Is there any real need for keyword "static inline" with
functions.

BTW, using inline has many caveats that you need to be aware of.

>From the working draft of ISO C Standard:

6.7.4 Function specifiers
Syntax
1 function-specifier:
inline
Constraints
2 Function specifiers shall be used only in the declaration of an
identifier for a function.
3 An inline definition of a function with external linkage shall not
contain a definition of a
modifiable object with static storage duration, and shall not contain
a reference to an
identifier with internal linkage.
4 In a hosted environment, the inline function specifier shall not
appear in a declaration
of main.
Semantics
5 A function declared with an inline function specifier is an inline
function. The
function specifier may appear more than once; the behavior is the
same as if it appeared
only once. Making a function an inline function suggests that calls
to the function be as
fast as possible.118) The extent to which such suggestions are
effective is
implementation-defined.119)
6 Any function with internal linkage can be an inline function. For a
function with external
linkage, the following restrictions apply: If a function is declared
with an inline
function specifier, then it shall also be defined in the same
translation unit. If all of the
file scope declarations for a function in a translation unit include
the inline function
specifier without extern, then the definition in that translation unit
is an inline
definition. An inline definition does not provide an external
definition for the function,
and does not forbid an external definition in another translation
unit. An inline definition
provides an alternative to an external definition, which a translator
may use to implement
any call to the function in the same translation unit. It is
unspecified whether a call to the
function uses the inline definition or the external definition.120 )

[jaysome]

Re: Is there a real need to use keyword static with functions?

On 5 Mar 2007 13:10:47 -0800, lcdgoncalves@gm ail.com wrote:

>Hi everyone
>
>Is there a real need to use keyword static with functions, if we
>simply don't declare their prototypes in .h file?
>
>Many textbooks avoid to discuss this matter and/or discuss only the
>usage of static functions. I've been programming for years and I never
>felt a real need for the "static approach for functions".
>
>I don't know if this is a trivial matter since the reserved word
>exists. :)
>Or it exists for some other purpose I can't figure out.
>
>What did I have missed? :)
>
>Thanks in advance for answers

In C, functions can have one of two types of linkage: external or
internal.

A function with external linkage can be defined only once and called
by multiple translation units, while a function with internal linkage
can be defined once for each translation unit and called (directly)
only by the translation unit that defines it (separate translation
units that define the same function with internal linkage effectively
get their own copy of the function definition).

The keyword static, when used in a function prototype or definition,
implies internal linkage, while the keyword extern (or lack of both
extern and static) in a function prototype or definition, implies
external linkage

All functions should have a prototype in scope, with the exception of
main().

Function prototypes declared in a .h file should not be declared as
static; you can declare them as extern, but that's not necessary.

/* foo.h */
static void foo1(void); /* bad */
void foo2(void); /* okay */
extern foo3(void); /* okay, though use of extern is superfluous */

Function prototypes declared in a .c file should use static. The
function definition whose prototype is declared with static can also
use static (but not extern), but that's not necessary, although it's
good practice.

/* foo.c */
static void foo4(void);

#ifdef DEFS_WITH_STATI C
static void foo4(void) /* okay */
{
/* implement foo4 */
}
#else
void foo4(void) /* okay */
{
/* implement foo4 */
}
#endif

Likewise, function definitions whose prototype is not declared with
static can also use extern (but not static), but that's not necessary,
although it's considered acceptable by some and suspect by others
(PC-lint falls into the latter category).

/* foo.c */
#include "foo.h"
#ifdef DEFS_WITH_EXTER N
extern void foo2(void) /* okay */
{
/* implement foo2 */
}
#else
void foo2(void) /* okay */
{
/* implement foo2 */
}
#endif

One argument for not using extern with function definitions is that
you can "grep" a .c source file for "extern" and expect to find no
matches.

Regards
--
jay

It's here!

http://www.microsoft.com/windows/products/windowsvista/

[CBFalconer]

Re: Is there a real need to use keyword static with functions?

santosh wrote:

pradeep wrote:
>
Please don't top-post. Your reply should be below or interspersed
with the material you quote. Irrelevant text can be deleted,
particularly sig blocks that follow a '-- ' marker.
[fixed]
>

.... snip ...

IIRC he's been told this before, and ignored it. Unless there are
multiple pradeeps extant, he is due to be plonked.

--
<http://www.cs.auckland .ac.nz/~pgut001/pubs/vista_cost.txt>
<http://www.securityfoc us.com/columnists/423>

"A man who is right every time is not likely to do very much."
-- Francis Crick, co-discover of DNA
"There is nothing more amazing than stupidity in action."
-- Thomas Matthews

[Roland Pibinger]

Re: Is there a real need to use keyword static with functions?

On 5 Mar 2007 13:41:06 -0800, "user923005 " <dcorbit@connx. comwrote:

>Functions should always be made static if they are not intended as end-
>user available routines.

IOW, static functions in C serve the same purpose as 'private'
funtions are in other languages.

Best wishes,
Roland Pibinger

[santosh]

Re: Is there a real need to use keyword static with functions?


Roland Pibinger wrote:

On 5 Mar 2007 13:41:06 -0800, "user923005 " <dcorbit@connx. comwrote:

Functions should always be made static if they are not intended as end-
user available routines.

>
IOW, static functions in C serve the same purpose as 'private'
funtions are in other languages.

Maybe in some senses of private. For example, C++'s private member
functions are quite different from C's static qualified functions.