«

On Sep 25, 2:09 pm, Richard Heathfield <r...@see.sig.invalid> wrote:
> user923005 said:
>
> <snip>
>
> > The main() function cannot be called from a user defined library.
>
> C&V please.
>
> > The main() function is special. It defines the entry point for
> > program startup.
>
> Agreed. Er, so? What stops you putting it in a library? Surely it's all one
> as far as the linker is concerned?
>
> --
> Richard Heathfield <http://www.cpax.org.uk>
> Email: -http://www. +rjh@
> Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
> "Usenet is a strange place" - dmr 29 July 1999

I can write a main function in another file and compile it as a
library link it to another program where there is no main , but some
sub functions which are called by main. and it works well.

On Sep 25, 2:17 pm, ravi <gototh...@gmail.com> wrote:
> On Sep 25, 2:09 pm, Richard Heathfield <r...@see.sig.invalid> wrote:
>
>
>
>
>
> > user923005 said:
>
> > <snip>
>
> > > The main() function cannot be called from a user defined library.
>
> > C&V please.
>
> > > The main() function is special. It defines the entry point for
> > > program startup.
>
> > Agreed. Er, so? What stops you putting it in a library? Surely it's all one
> > as far as the linker is concerned?
>
> > --
> > Richard Heathfield <http://www.cpax.org.uk>
> > Email: -http://www. +rjh@
> > Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
> > "Usenet is a strange place" - dmr 29 July 1999
>
> I can write a main function in another file and compile it as a
> library link it to another program where there is no main , but some
> sub functions which are called by main. and it works well.- Hide quoted text -
>
> - Show quoted text -

How is this possible ?

Thx,
Karthik Balaguru

On 25 sep, 07:03, ravi <gototh...@gmail.com> wrote:
> Hello everybody,
>
> I am writing a small application which does some work before the user
> main function starts execution.
>
> I am trying to #define the main function.
>
> But the problem is that,
>
> the main () function by user may be of different types
> 1. main()

not conformant -> int main(void)

> 2.main(int argc)

not conformant

> 3. main(int argc, char *argv[])


// prelude, already posted here many times
#define COS_PP_CAT(a,b) COS_PP_CAT_(a,b)
#define COS_PP_CAT_(a,b) a ## b
#define COS_PP_NARG_(...) COS_PP_NARG_N_(__VA_ARGS__)
#define COS_PP_NARG_N_( \
_1, _2, _3, _4, _5, _6, _7, _8, _9,_10, \
_11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \
_21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \
_31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \
_41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \
_51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \
_61,_62,_63,N,...) N
#define COS_PP_CAT_NARG(a,...) COS_PP_CAT(a,COS_PP_NARG(__VA_ARGS__))

// your problem
#define main(...) \
COS_PP_CAT_NARG(MAIN_,__VA_ARGS__)(__VA_ARGS__)

#define MAIN_1() \
main(void) { \
int user_main(void); \
your_main(0,0); \
user_main(); \
} \
int user_main(void)

#define MAIN_2(ARGC,ARGV) \
main(int argc, char *argv[]) { \
int user_main(ARGC,ARGV); \
your_main(argc,argv); \
user_main(argc,argv); \
}
int user_main(ARGC,ARGV)

int main(int my_argc, char *my_argc[])
{
// code using my_argc and my_argv after your_main() has been called.
}

I just wrote this code on the fly, so it is untested and assumes the
availability of c99 variadic macros.

I use very often this kind of macro dispatch based on its number of
argument in COS (macros with optional arguments). PP_NARG has been
left as posted here in the past, but you could reduce the maximum
number of argument for you case.

a+, ld.

On Sep 25, 3:27 pm, karthikbalaguru <karthikbalagur...@gmail.com>
wrote:
> On Sep 25, 2:17 pm, ravi <gototh...@gmail.com> wrote:
>
>
>
> > On Sep 25, 2:09 pm, Richard Heathfield <r...@see.sig.invalid> wrote:
>
> > > user923005 said:
>
> > > <snip>
>
> > > > The main() function cannot be called from a user defined library.
>
> > > C&V please.
>
> > > > The main() function is special. It defines the entry point for
> > > > program startup.
>
> > > Agreed. Er, so? What stops you putting it in a library? Surely it's all one
> > > as far as the linker is concerned?
>
> > > --
> > > Richard Heathfield <http://www.cpax.org.uk>
> > > Email: -http://www. +rjh@
> > > Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
> > > "Usenet is a strange place" - dmr 29 July 1999
>
> > I can write a main function in another file and compile it as a
> > library link it to another program where there is no main , but some
> > sub functions which are called by main. and it works well.- Hide quoted text -
>
> > - Show quoted text -
>
> How is this possible ?
>
> Thx,
> Karthik Balaguru

give a trial.
Write a file with main() function calling a function foo().
main.c :
int main()
{
printf("MAIN\n");
foo();
return 0;
}

Compile it and make it a library like this:
> gcc -c main.c -o main.o
> ar -rc libmain.a main.o

Now write a file foo.c with foo() function.
foo.c:
void foo()
{
printf("FOOOOOOOOO\n");
}
Now compile like this:
> gcc foo.c -lmain
it works and u can try running.

--
Ravi.T

On Sep 25, 3:45 pm, ravi <gototh...@gmail.com> wrote:
> On Sep 25, 3:27 pm, karthikbalaguru <karthikbalagur...@gmail.com>
> wrote:
>
>
>
>
>
> > On Sep 25, 2:17 pm, ravi <gototh...@gmail.com> wrote:
>
> > > On Sep 25, 2:09 pm, Richard Heathfield <r...@see.sig.invalid> wrote:
>
> > > > user923005 said:
>
> > > > <snip>
>
> > > > > The main() function cannot be called from a user defined library.
>
> > > > C&V please.
>
> > > > > The main() function is special. It defines the entry point for
> > > > > program startup.
>
> > > > Agreed. Er, so? What stops you putting it in a library? Surely it's all one
> > > > as far as the linker is concerned?
>
> > > > --
> > > > Richard Heathfield <http://www.cpax.org.uk>
> > > > Email: -http://www. +rjh@
> > > > Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
> > > > "Usenet is a strange place" - dmr 29 July 1999
>
> > > I can write a main function in another file and compile it as a
> > > library link it to another program where there is no main , but some
> > > sub functions which are called by main. and it works well.- Hide quoted text -
>
> > > - Show quoted text -
>
> > How is this possible ?
>
> > Thx,
> > Karthik Balaguru
>
> give a trial.
> Write a file with main() function calling a function foo().
> main.c :
> int main()
> {
> printf("MAIN\n");
> foo();
> return 0;
> }
>
> Compile it and make it a library like this:
> > gcc -c main.c -o main.o
> > ar -rc libmain.a main.o
>
> Now write a file foo.c with foo() function.
> foo.c:
> void foo()
> {
> printf("FOOOOOOOOO\n");
> }
> Now compile like this:
> > gcc foo.c -lmain
> it works and u can try running.
>
> --
> Ravi.T- Hide quoted text -
>
> - Show quoted text -

How do u say that it works ?
What did u get on the console ?

Karthik Balaguru

karthikbalaguru <> writes:

> On Sep 25, 2:17 pm, ravi <gototh...@gmail.com> wrote:
>> On Sep 25, 2:09 pm, Richard Heathfield <r...@see.sig.invalid> wrote:
>>
>>
>>
>>
>>
>> > user923005 said:
>>
>> > <snip>
>>
>> > > The main() function cannot be called from a user defined library.
>>
>> > C&V please.
>>
>> > > The main() function is special. It defines the entry point for
>> > > program startup.
>>
>> > Agreed. Er, so? What stops you putting it in a library? Surely it's all one
>> > as far as the linker is concerned?
>>
>> > --
>> > Richard Heathfield <http://www.cpax.org.uk>
>> > Email: -http://www. +rjh@
>> > Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
>> > "Usenet is a strange place" - dmr 29 July 1999
>>
>> I can write a main function in another file and compile it as a
>> library link it to another program where there is no main , but some
>> sub functions which are called by main. and it works well.- Hide quoted text -
>>
>> - Show quoted text -
>
> How is this possible ?

You should ask "why would it NOT be possible"?

If main calls 3 functions - a(),b() and c() what's to stop you linking in
different versions of these functions for the same main() for different purposes?

Thanks Deniau.

On Sep 25, 3:42 pm, Laurent Deniau <Laurent.Den...@gmail.com> wrote:
> On 25 sep, 07:03, ravi <gototh...@gmail.com> wrote:
>
> > Hello everybody,
>
> > I am writing a small application which does some work before the user
> > main function starts execution.
>
> > I am trying to #define the main function.
>
> > But the problem is that,
>
> > the main () function by user may be of different types
> > 1. main()
>
> not conformant -> int main(void)
>
> > 2.main(int argc)
>
> not conformant
>
> > 3. main(int argc, char *argv[])
>
> // prelude, already posted here many times
> #define COS_PP_CAT(a,b) COS_PP_CAT_(a,b)
> #define COS_PP_CAT_(a,b) a ## b
> #define COS_PP_NARG_(...) COS_PP_NARG_N_(__VA_ARGS__)
> #define COS_PP_NARG_N_( \
> _1, _2, _3, _4, _5, _6, _7, _8, _9,_10, \
> _11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \
> _21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \
> _31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \
> _41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \
> _51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \
> _61,_62,_63,N,...) N


Where r u calling this macro COS_PP_NARG_N_(__VA_ARGS__).
How does it replace _1/_2/_3......... how it detects the count of
arguments?
please clarify me.


> #define COS_PP_CAT_NARG(a,...) COS_PP_CAT(a,COS_PP_NARG(__VA_ARGS__))
>
> // your problem
> #define main(...) \
> COS_PP_CAT_NARG(MAIN_,__VA_ARGS__)(__VA_ARGS__)
>
> #define MAIN_1() \
> main(void) { \
> int user_main(void); \
> your_main(0,0); \
> user_main(); \
> } \
> int user_main(void)
>
> #define MAIN_2(ARGC,ARGV) \
> main(int argc, char *argv[]) { \
> int user_main(ARGC,ARGV); \
> your_main(argc,argv); \
> user_main(argc,argv); \
> }
> int user_main(ARGC,ARGV)
>
> int main(int my_argc, char *my_argc[])
> {
> // code using my_argc and my_argv after your_main() has been called.
>
> }
>
> I just wrote this code on the fly, so it is untested and assumes the
> availability of c99 variadic macros.
>
> I use very often this kind of macro dispatch based on its number of
> argument in COS (macros with optional arguments). PP_NARG has been
> left as posted here in the past, but you could reduce the maximum
> number of argument for you case.
>
> a+, ld.

Thanks Deniau.

On Sep 25, 3:42 pm, Laurent Deniau <Laurent.Den...@gmail.com> wrote:
> On 25 sep, 07:03, ravi <gototh...@gmail.com> wrote:
>
> > Hello everybody,
>
> > I am writing a small application which does some work before the user
> > main function starts execution.
>
> > I am trying to #define the main function.
>
> > But the problem is that,
>
> > the main () function by user may be of different types
> > 1. main()
>
> not conformant -> int main(void)
>
> > 2.main(int argc)
>
> not conformant
>
> > 3. main(int argc, char *argv[])
>
> // prelude, already posted here many times
> #define COS_PP_CAT(a,b) COS_PP_CAT_(a,b)
> #define COS_PP_CAT_(a,b) a ## b
> #define COS_PP_NARG_(...) COS_PP_NARG_N_(__VA_ARGS__)
> #define COS_PP_NARG_N_( \
> _1, _2, _3, _4, _5, _6, _7, _8, _9,_10, \
> _11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \
> _21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \
> _31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \
> _41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \
> _51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \
> _61,_62,_63,N,...) N


Where r u calling this macro COS_PP_NARG_N_(__VA_ARGS__).
How does it replace _1/_2/_3......... how it detects the count of
arguments?
please clarify me.


> #define COS_PP_CAT_NARG(a,...) COS_PP_CAT(a,COS_PP_NARG(__VA_ARGS__))
>
> // your problem
> #define main(...) \
> COS_PP_CAT_NARG(MAIN_,__VA_ARGS__)(__VA_ARGS__)
>
> #define MAIN_1() \
> main(void) { \
> int user_main(void); \
> your_main(0,0); \
> user_main(); \
> } \
> int user_main(void)
>
> #define MAIN_2(ARGC,ARGV) \
> main(int argc, char *argv[]) { \
> int user_main(ARGC,ARGV); \
> your_main(argc,argv); \
> user_main(argc,argv); \
> }
> int user_main(ARGC,ARGV)
>
> int main(int my_argc, char *my_argc[])
> {
> // code using my_argc and my_argv after your_main() has been called.
>
> }
>
> I just wrote this code on the fly, so it is untested and assumes the
> availability of c99 variadic macros.
>
> I use very often this kind of macro dispatch based on its number of
> argument in COS (macros with optional arguments). PP_NARG has been
> left as posted here in the past, but you could reduce the maximum
> number of argument for you case.
>
> a+, ld.

On 25 sep, 14:11, ravi <gototh...@gmail.com> wrote:
> Thanks Deniau.
>
> On Sep 25, 3:42 pm, Laurent Deniau <Laurent.Den...@gmail.com> wrote:
>
>
>
> > On 25 sep, 07:03, ravi <gototh...@gmail.com> wrote:
>
> > > Hello everybody,
>
> > > I am writing a small application which does some work before the user
> > > main function starts execution.
>
> > > I am trying to #define the main function.
>
> > > But the problem is that,
>
> > > the main () function by user may be of different types
> > > 1. main()
>
> > not conformant -> int main(void)
>
> > > 2.main(int argc)
>
> > not conformant
>
> > > 3. main(int argc, char *argv[])
>
> > // prelude, already posted here many times
> > #define COS_PP_CAT(a,b) COS_PP_CAT_(a,b)
> > #define COS_PP_CAT_(a,b) a ## b
> > #define COS_PP_NARG_(...) COS_PP_NARG_N_(__VA_ARGS__)
> > #define COS_PP_NARG_N_( \
> > _1, _2, _3, _4, _5, _6, _7, _8, _9,_10, \
> > _11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \
> > _21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \
> > _31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \
> > _41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \
> > _51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \
> > _61,_62,_63,N,...) N
>
> Where r u calling this macro COS_PP_NARG_N_(__VA_ARGS__).
> How does it replace _1/_2/_3......... how it detects the count of
> arguments?
> please clarify me.

Oops, I usual with untested code some macros are missing (googleing
this newsgroup or comp.std.c would have pointed my OP on this macro
some years ago):

#define COS_PP_NARG(...) COS_PP_NARG_(__VA_ARGS__,COS_PP_REVSEQ_N(),)
#define COS_PP_REVSEQ_N() \
63,62,61, \
60,59,58,57,56,55,54,53,52,51, \
50,49,48,47,46,45,44,43,42,41, \
40,39,38,37,36,35,34,33,32,31, \
30,29,28,27,26,25,24,23,22,21, \
20,19,18,17,16,15,14,13,12,11, \
10, 9, 8, 7, 6, 5, 4, 3, 2, 1

>
> > #define COS_PP_CAT_NARG(a,...) COS_PP_CAT(a,COS_PP_NARG(__VA_ARGS__))
>
> > // your problem
> > #define main(...) \
> > COS_PP_CAT_NARG(MAIN_,__VA_ARGS__)(__VA_ARGS__)
>
> > #define MAIN_1() \
> > main(void) { \
> > int user_main(void); \
> > your_main(0,0); \
> > user_main(); \
> > } \
> > int user_main(void)
>
> > #define MAIN_2(ARGC,ARGV) \
> > main(int argc, char *argv[]) { \
> > int user_main(ARGC,ARGV); \
> > your_main(argc,argv); \
> > user_main(argc,argv); \
> > }
> > int user_main(ARGC,ARGV)
>
> > int main(int my_argc, char *my_argc[])
> > {
> > // code using my_argc and my_argv after your_main() has been called.
>
> > }
>
> > I just wrote this code on the fly, so it is untested and assumes the
> > availability of c99 variadic macros.
>
> > I use very often this kind of macro dispatch based on its number of
> > argument in COS (macros with optional arguments). PP_NARG has been
> > left as posted here in the past, but you could reduce the maximum
> > number of argument for you case.
>
> > a+, ld.

On Mon, 24 Sep 2007 22:49:37 -0700, ravi wrote:

> Can you please try this program:
> example.c:
> int main(int argc)
> {
> printf("Hello World\n");
> return 0;
> }
> I am able to compile and run this.

Can you please try this program:
#include <time.h>
#include <stdio.h>
size_t main(struct tm argc)
{
return puts("hello, world") < 0 ? 0x17 : !mktime(&argc);
}
I am able to compile and run this.
--
Army1987 (Replace "NOSPAM" with "email")
A hamburger is better than nothing.
Nothing is better than eternal happiness.
Therefore, a hamburger is better than eternal happiness.