#ifndef OF /* function prototypes */
# ifdef STDC
# define OF(args) args
# else
# define OF(args) ()
# endif
#endif

void func OF( args );

I saw some C programs written like this. Why?

StdNewer wrote:
> #ifndef OF /* function prototypes */
> # ifdef STDC
> # define OF(args) args

Are you sure that wasn't define OF(args) (args)?

> # else
> # define OF(args) ()
> # endif
> #endif
>
> void func OF( args );
>
> I saw some C programs written like this. Why?

Very old (before 1989) compilers didn't have function prototypes.
Expand the macros and see what you get with and without STDC defined.

--
Ian Collins.

On 2ÔÂ2ÈÕ, ÏÂÎç2ʱ42·Ö, Ian Collins <ian-n...@hotmail.com> wrote:
> StdNewer wrote:
> > #ifndef OF /* function prototypes */
> > # ifdef STDC
> > # define OF(args) args
>
> Are you sure that wasn't define OF(args) (args)?

I see,thanks very much.
I wrote wrong in "void func OF(args)"; it should be: void func
OF((args));
But if "#define OF(args) ()",this function is vod fun(()).
two parentheses,right?
why didn't he define "OF" as you do,and declare function as
func OF(),not func OF(())?

Ian Collins <ian-news@hotmail.com> writes:

> StdNewer wrote:
>> #ifndef OF /* function prototypes */
>> # ifdef STDC
>> # define OF(args) args
>
> Are you sure that wasn't define OF(args) (args)?

Probably not: then it would only work with 0- or 1-parameter
functions, because a 1-argument macro cannot be invoked with
multiple comma-separated arguments.
--
char a[]="\n .CJacehknorstu";int putchar(int);int main(void){unsigned long b[]
={0x67dffdff,0x9aa9aa6a,0xa77ffda9,0x7da6aa6a,0xa6 7f6aaa,0xaa9aa9f6,0x11f6},*p
=b,i=24;for(+=!*p;*p/=4)switch(0[p]&3)case 0:{return 0;for(p--;i--;i--)case+
2:{i++;if(i)break;else default:continue;if(0)case 1:putchar(a[i&15]);break;}}}

StdNewer wrote:
> On 2ÔÂ2ÈÕ, ÏÂÎç2ʱ42·Ö, Ian Collins <ian-n...@hotmail.com> wrote:
>> StdNewer wrote:
>>> #ifndef OF /* function prototypes */
>>> # ifdef STDC
>>> # define OF(args) args
>> Are you sure that wasn't define OF(args) (args)?
>
> I see,thanks very much.
> I wrote wrong in "void func OF(args)"; it should be: void func
> OF((args));
> But if "#define OF(args) ()",this function is vod fun(()).
> two parentheses,right?
> why didn't he define "OF" as you do,and declare function as
> func OF(),not func OF(())?
>
See Ben's reply.

--
Ian Collins.