Static function prototype

[Why Tea]

I seem to remember that in ANSI C, all static functions should have
their function prototypes listed at the beginning of the file for
better consistency (or something like that). I googled and didn't find
any good explanation about it. Could the experts please give me an
explanation or point me to some link? Thanks!

/Why Tea

[danmath06@gmail.com]

Re: Static function prototype

On Oct 3, 2:08 pm, Why Tea <ytl...@gmail.c omwrote:

I seem to remember that in ANSI C, all static functions should have
their function prototypes listed at the beginning of the file for
better consistency (or something like that). I googled and didn't find
any good explanation about it. Could the experts please give me an
explanation or point me to some link? Thanks!
>
/Why Tea

In a file each function can only see the ones declared above it.
That's why it's good practice to have all the prototypes at the top of
the file. The functions that have not been declared before you invoke
them will be asumed to return int and as far as I know the arguments
will not be checked because there is no definition to check them
against to. This applies to all functions static or not.

[Eric Sosman]

Re: Static function prototype

Why Tea wrote:

I seem to remember that in ANSI C, all static functions should have
their function prototypes listed at the beginning of the file for
better consistency (or something like that). I googled and didn't find
any good explanation about it. Could the experts please give me an
explanation or point me to some link? Thanks!

Stepping back a little, it's always been good practice to
declare functions, static or otherwise, before using them. (C99
makes this not just good practice, but a requirement.) And ever
since ANSI C appeared, it's been good practice to use prototypes
in function declarations and definitions. So the advice about
declaring functions applies to all functions, not just to static
functions.

Now to matters of layout, which is what your question really
boils down to. Non-static functions in "serious" programs should
usually be declared by including the associated headers, so all
you see in the .c source file is usually a few #include directives.
Static functions should almost never be declared in headers: You
made them static because you wanted their names to be visible only
inside one module, so why would you export those names to other
modules? Thus, static functions are usually declared differently
from external functions -- the declarations themselves look the
same, apart from `static', but their placement is different.

Two principal styles of arranging functions within a module
are commonly seen. One puts the top-level functions -- main(),
for example -- early in the file, with subordinate functions later
and low-level "leaf" functions last of all. In this style the
function's definition usually appears after at least one of its
calls, perhaps after all of them, so good practice (or C99's
mandate) calls for putting a separate declaration somewhere prior
to the first use. The top of the file is a pretty good location.

Some people (I'm one of them) dislike telling the compiler the
same thing twice; it irks us to declare that foo() takes two int
arguments and returns a double, and then turn right around and
write the actual definition of foo() with two int arguments and a
double result. When we get irked enough, we sometimes take advantage
of the fact that a function's definition can also serve as its
declaration: If the definition appears before the function's first
use, no separate declaration is needed. So we write the module
"upside-down" or "Pascal-style:" low-level "leaf" functions at the
top, followed by intermediate-level functions, and the Big Kahuna
last of all, each function declared by its own definition.

If you've got two or more mutually recursive functions -- f()
calls g() *and* g() calls f() -- you won't be able to use the
definitions-are-declarations strategy for all of them. If f()
appears first, its call to g() appears before the definition of g()
and you'll need to insert a separate declaration of g() somewhere
before f() in the file.

--
Eric.Sosman@sun .com

[Why Tea]

Re: Static function prototype

On Oct 3, 11:59 am, Eric Sosman <Eric.Sos...@su n.comwrote:

Why Tea wrote:

I seem to remember that in ANSI C, all static functions should have
their function prototypes listed at the beginning of the file for
better consistency (or something like that). I googled and didn't find
any good explanation about it. Could the experts please give me an
explanation or point me to some link? Thanks!

>
     Stepping back a little, it's always been good practice to
declare functions, static or otherwise, before using them.  (C99
makes this not just good practice, but a requirement.)  And ever
since ANSI C appeared, it's been good practice to use prototypes
in function declarations and definitions.  So the advice about
declaring functions applies to all functions, not just to static
functions.
>
     Now to matters of layout, which is what your question really
boils down to.  Non-static functions in "serious" programs should
usually be declared by including the associated headers, so all
you see in the .c source file is usually a few #include directives.
Static functions should almost never be declared in headers: You
made them static because you wanted their names to be visible only
inside one module, so why would you export those names to other
modules?  Thus, static functions are usually declared differently
from external functions -- the declarations themselves look the
same, apart from `static', but their placement is different.
>
     Two principal styles of arranging functions within a module
are commonly seen.  One puts the top-level functions -- main(),
for example -- early in the file, with subordinate functions later
and low-level "leaf" functions last of all.  In this style the
function's definition usually appears after at least one of its
calls, perhaps after all of them, so good practice (or C99's
mandate) calls for putting a separate declaration somewhere prior
to the first use.  The top of the file is a pretty good location.
>
     Some people (I'm one of them) dislike telling the compiler the
same thing twice; it irks us to declare that foo() takes two int
arguments and returns a double, and then turn right around and
write the actual definition of foo() with two int arguments and a
double result.  When we get irked enough, we sometimes take advantage
of the fact that a function's definition can also serve as its
declaration: If the definition appears before the function's first
use, no separate declaration is needed.  So we write the module
"upside-down" or "Pascal-style:" low-level "leaf" functions at the
top, followed by intermediate-level functions, and the Big Kahuna
last of all, each function declared by its own definition.
>
     If you've got two or more mutually recursive functions -- f()
calls g() *and* g() calls f() -- you won't be able to use the
definitions-are-declarations strategy for all of them.  If f()
appears first, its call to g() appears before the definition of g()
and you'll need to insert a separate declaration of g() somewhere
before f() in the file.
>
--
Eric.Sos...@sun .com

Thanks Eric for such a clear explanation. While I get your attention,
can we take a look at "extern" as well? :) If we have all exported
functions and global variables included in a header file, does
it mean that there is really no need to use extern (in the module
that needs to access those functions and global variables) as we
can simply #include the header file? What are the needs/advantages
of using extern?

/Why Tea

[s0suk3@gmail.com]

Re: Static function prototype

On Oct 3, 1:28 pm, Why Tea <ytlim1@gmail.c omwrote:

On Oct 3, 11:59 am, Eric Sosman <Eric.Sos...@su n.comwrote:

<snip>

Thanks Eric for such a clear explanation. While I get your attention,
can we take a look at "extern" as well? :) If we have all exported
functions and global variables included in a header file, does
it mean that there is really no need to use extern (in the module
that needs to access those functions and global variables) as we
can simply #include the header file? What are the needs/advantages
of using extern?

None. The 'extern' storage class in the declaration/definition of a
function serves no purpose whatsoever. 'extern' suggests that the
function has external linkage, but that is the default for functions
anyway. In other words, declaring/defining a function to be 'extern'
is like defining a local variable to be 'auto'.

Sebastian

[Jack Klein]

Re: Static function prototype

On Fri, 3 Oct 2008 14:17:34 -0700 (PDT), s0suk3@gmail.co m wrote in
comp.lang.c:

On Oct 3, 1:28 pm, Why Tea <ytlim1@gmail.c omwrote:

On Oct 3, 11:59 am, Eric Sosman <Eric.Sos...@su n.comwrote:

<snip>

Thanks Eric for such a clear explanation. While I get your attention,
can we take a look at "extern" as well? :) If we have all exported
functions and global variables included in a header file, does
it mean that there is really no need to use extern (in the module
that needs to access those functions and global variables) as we
can simply #include the header file? What are the needs/advantages
of using extern?

>
None. The 'extern' storage class in the declaration/definition of a
function serves no purpose whatsoever. 'extern' suggests that the
function has external linkage, but that is the default for functions
anyway. In other words, declaring/defining a function to be 'extern'
is like defining a local variable to be 'auto'.

The extern keyword in C does not specify a storage class, it specifies
a linkage type. It can only be applied to objects with static storage
duration, or to functions. But it does not in itself confer any sort
of storage duration on objects, merely requires that they already have
static storage duration.

--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
comp.lang.c http://c-faq.com/
comp.lang.c++ http://www.parashift.com/c++-faq-lite/
alt.comp.lang.l earn.c-c++

http://www.club.cc.cmu.edu/~ajo/docs/FAQ-acllc.html

[Malcolm McLean]

Re: Static function prototype

"Antoninus Twink" <nospam@nospam. invalidwrote in message

>
Have you considered using a more sophisticated editor than MS NotePad?
>

For a long time I did all my programming from the Visual Studio GUI. You get
into the way of working with it. It's a very intimate thing, a bit like
driving a car.

Then times change, a Beowulf cluster appears, and suddenly that delightful
GUI is taken away. It's actually better to get into the habit of typing
things into simple ASCII editors and using printf() as your debugger. Now I
use emacs. it is a tremendously powerful editor, but I am quite incapable of
doing anything clever with it. I close it down and use grep when I need to
search for a function.

--
Free games and programming goodies.

http://www.personal.leeds.ac.uk/~bgy1mm

[CBFalconer]

Re: Static function prototype

Malcolm McLean wrote:

"Antoninus Twink" <nospam@nospam. invalidwrote in message
>

>Have you considered using a more sophisticated editor than MS
>NotePad?

>
For a long time I did all my programming from the Visual Studio
GUI. You get into the way of working with it. It's a very
intimate thing, a bit like driving a car.
>

.... snip ...

--
+-------------------+ .:\:\:/:/:.
| PLEASE DO NOT F :.:\:\:/:/:.:
| FEED THE TROLLS | :=.' - - '.=:
| | '=(\ 9 9 /)='
| Thank you, | ( (_) )
| Management | /`-vvv-'\
+-------------------+ / \
| | @@@ / /|,,,,,|\ \
| | @@@ /_// /^\ \\_\
@x@@x@ | | |/ WW( ( ) )WW
\||||/ | | \| __\,,\ /,,/__
\||/ | | | jgs (______Y______)
/\/\/\/\/\/\/\/\//\/\\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
=============== =============== =============== =============== ==

fix (vb.): 1. to paper over, obscure, hide from public view; 2.
to work around, in a way that produces unintended consequences
that are worse than the original problem. Usage: "Windows ME
fixes many of the shortcomings of Windows 98 SE". - Hutchinson

[Giorgos Keramidas]

Re: Static function prototype

On Sat, 4 Oct 2008 16:11:29 +0100, "Malcolm McLean" <regniztar@btin ternet.comwrote :

>"Antoninus Twink" <nospam@nospam. invalidwrote in message

>Have you considered using a more sophisticated editor than MS NotePad?

>
For a long time I did all my programming from the Visual Studio
GUI. You get into the way of working with it. It's a very intimate
thing, a bit like driving a car.
>
Then times change, a Beowulf cluster appears, and suddenly that
delightful GUI is taken away. It's actually better to get into the
habit of typing things into simple ASCII editors and using printf() as
your debugger. Now I use emacs. it is a tremendously powerful editor,
but I am quite incapable of doing anything clever with it. I close it
down and use grep when I need to search for a function.

This is off-topic for comp.lang.c, so I've set the `Followup-To' header
appropriately.

Emacs is, indeed, a powerful editing application. It may be interesting
for your editing sessions to read the following pages of the Emacs Wiki:

http://www.emacswiki.org/cgi-bin/wiki/GrepMode

http://www.emacswiki.org/cgi-bin/wiki/RecursiveGrep

The Emacs manual describes various ways of launching grep-like searches
from within Emacs too. See the section ``Searching with Grep under
Emacs'' in the manual.

In recent Emacs releases (i.e. 22.1 or later) you can open this section
by typing

C-h r i grep RET

The `C-h r' keys will launch the Emacs manual in Info mode, and the rest
of the key sequence (the `i grep RET' keys) will open the grep section
by looking up the term `grep' in the index of the manual.

Please feel free to ask about other useful things you want to do with
your Emacs installations, by posting email questions to

help-gnu-emacs@gnu.org

or by posting your questions through Usenet to the `news:gnu.emacs .help'
group.

Have fun with your Emacs installations,
Giorgos

[Nick Keighley]

Re: Static function prototype

On 4 Oct, 08:06, CBFalconer <cbfalco...@yah oo.comwrote:

<snip>

I invariably foul up the usage of 'declared' versus 'defined'.  At
least I know what I mean. :-)

me too. In fact I'm half convinced that Cs usage is the opposite
of some other language I used (pascal?). This is why I the definition
of definition written on the wall. I check my wall everytime
I post about definion or declaration.

My practice is to declare everything before use, if possible.

yes. Old pascal habbit.

Obviously mutual recursion alters this.  But that avoids ever
needing to maintain two source chunks to have the identical
meaning.

The code equivalent of Normal Form.


--
Nick Keighley

"The key, the whole key and nothing but the key,
So thank me Codd"

[CBFalconer]

Re: Static function prototype

Nick Keighley wrote:

CBFalconer <cbfalco...@yah oo.comwrote:
>

.... snip ...

>

>My practice is to declare everything before use, if possible.

>
yes. Old pascal habbit.

I maintain that ex-ISO-Pascalers write better organized code. :-)

--
[mail]: Chuck F (cbfalconer at maineline dot net)
[page]: <http://cbfalconer.home .att.net>
Try the download section.

[Ben Pfaff]

Re: Static function prototype

CBFalconer <cbfalconer@yah oo.comwrites:

Nick Keighley wrote:

>CBFalconer <cbfalco...@yah oo.comwrote:

>>My practice is to declare everything before use, if possible.

>>
>yes. Old pascal habbit.

>
I maintain that ex-ISO-Pascalers write better organized code. :-)

Like this?
while ((EOF != (ch = getchar()))} && isspace(ch)) continue;
Ugh. It even has a stray }.
--
"Some programming practices beg for errors;
this one is like calling an 800 number
and having errors delivered to your door."
--Steve McConnell

[Antoninus Twink]

Re: Static function prototype

On 6 Oct 2008 at 21:10, Ben Pfaff wrote:

CBFalconer <cbfalconer@yah oo.comwrites:

>I maintain that ex-ISO-Pascalers write better organized code. :-)

>
Like this?
while ((EOF != (ch = getchar()))} && isspace(ch)) continue;
Ugh. It even has a stray }.

Yup - CBF's train-wreck style of coding is an affront to taste and
decency.

Hopefully there won't be any impressionable newbies who follow his
example and create hard-to-read, hard-to-debug monstrosities like the
line above.

[CBFalconer]

Re: Static function prototype

Ben Pfaff wrote:

CBFalconer <cbfalconer@yah oo.comwrites:

>Nick Keighley wrote:

>>CBFalconer <cbfalco...@yah oo.comwrote:
>>>
>>>My practice is to declare everything before use, if possible.
>>>
>>yes. Old pascal habbit.

>>
>I maintain that ex-ISO-Pascalers write better organized code. :-)

>
Like this?
while ((EOF != (ch = getchar()))} && isspace(ch)) continue;
Ugh. It even has a stray }.

That's a mistyped ')'. The statement itself isn't allowed in
Pascal, because assignments can't be propagated in expressions.
Also eof is a condition, not a macro value.

--
[mail]: Chuck F (cbfalconer at maineline dot net)
[page]: <http://cbfalconer.home .att.net>
Try the download section.

[Ben Pfaff]

Re: Static function prototype

CBFalconer <cbfalconer@yah oo.comwrites:

Ben Pfaff wrote:

>CBFalconer <cbfalconer@yah oo.comwrites:

>>Nick Keighley wrote:
>>>CBFalconer <cbfalco...@yah oo.comwrote:
>>>>
>>>>My practice is to declare everything before use, if possible.
>>>>
>>>yes. Old pascal habbit.
>>>
>>I maintain that ex-ISO-Pascalers write better organized code. :-)

>>
>Like this?
> while ((EOF != (ch = getchar()))} && isspace(ch)) continue;
>Ugh. It even has a stray }.

>
That's a mistyped ')'. The statement itself isn't allowed in
Pascal, because assignments can't be propagated in expressions.
Also eof is a condition, not a macro value.

Um, that's your own code, from article <48EA7C6E.148A0 444@yahoo.com>.
--
char a[]="\n .CJacehknorstu" ;int putchar(int);in t main(void){unsi gned long b[]
={0x67dffdff,0x 9aa9aa6a,0xa77f fda9,0x7da6aa6a ,0xa67f6aaa,0xa a9aa9f6,0x11f6} ,*p
=b,i=24;for(;p+ =!*p;*p/=4)switch(0[p]&3)case 0:{return 0;for(p--;i--;i--)case+
2:{i++;if(i)bre ak;else default:continu e;if(0)case 1:putchar(a[i&15]);break;}}}