usage of _PROTOTYPE ?

babbab · 09-26-2012, 09:14 PM

part of codes
....
<code>

#if 0
_PROTOTYPE(int main, (int argc, char **argv));
_PROTOTYPE(void count, (FILE *f));
_PROTOTYPE(void usage, (void));
#endif

int main (int argc, char **argv);
void count (FILE *f);
void usage (void);

int main(argc, argv)
int argc;
char *argv[];
{
int k;
char *cp;
int tflag, files;

</code>
....
more codes

and this compiled OK

I have two questions. the function prototype is ansi style and function definition is K&R style how does compiler compiles this codes OK if they do not match in style?

and How do you use _PROTOTYPE macro

Thank you for reading my post.

NevemTeve · 09-26-2012, 10:33 PM

Don't use this _PROTOTYPE macro. Actually, you can safely delete everything between #if 0 and #endif.
Don't use non-ANSI compilers either -- it's 2012 now, not 1982.
Do use [code] and [/code] tags.

PS: the old-style function-parameter-definition is still usable, but obsolete.

babbab · 09-26-2012, 11:25 PM

The code is from i think around 1985. since I'm re-writing the old code, I'm not gonna use the _PROTOTYPE macro but I still do need to understand how things work.

I'll appreciate if someone takes a time and explains this.

NevemTeve · 09-27-2012, 02:20 AM

Do you have any questions I haven't answered yet?

> I have two questions.
> The function prototype is ansi style and function definition is K&R style how does compiler compiles this codes OK if they do not match in style?

There is nothing preventing using both styles, but in new programs you shouldn't use old style.

> How do you use _PROTOTYPE macro?

You don't. You see it is between #if 0 and #endif, meaning: 'dear compiler, ignore this part'

babbab · 09-27-2012, 03:27 PM

> Do you have any questions I haven't answered yet?

No.. I thank you for answering it, appreciate it

>> How do you use _PROTOTYPE macro?

> You don't. You see it is between #if 0 and #endif, meaning: 'dear compiler, ignore this part'

.. I quoted with #if 0, #endif to see the effect. and put ansi style prototype. I was surprised to see the source was compiled without any errors.

I guess what I was expecting was more like there is this kind of macro code somewhere else then that expands above code and it has effect of resulting such such... then it compiles the above code without any errors

NevemTeve · 09-28-2012, 02:57 AM

Note: I guess this _PROTOTYPE macro might be sg like this:

Code:

#ifdef __STDC__
    #define _PROTOTYPE(begin, end) begin end
#else
    #define _PROTOTYPE(begin, end) begin ()
#endif

So it doesn't do anything non-trivial:

Code:

input:  _PROTOTYPE(void count, (FILE *f));
output: void count (FILE *f);