Very Computer

Hi, wonder if anyone can advice. I've got a C program with two (yes two!)
main() functions. During compilation I want only want part to compile
depending on what has been passed to gcc.

I've heard that I should be able to do something like

        #ifdef SECTION_1
        int main(int argc, char *argv)
        {
                /* First version of main() */
                .......
        }
        #endif

        #ifdef SECTION_2
        int main(int argc, char *argv)
        {
                /* Second version of main() */
                .......
        }
        #endif

and during compile I should be able to do something like
        gcc -DSECTION_2 progname.c -o progname
to compile SECTION_2 only but I've not been very successful. Any ideas?
Thanks.

Quote:> and during compile I should be able to do something like
>         gcc -DSECTION_2 progname.c -o progname
> to compile SECTION_2 only but I've not been very successful. Any ideas?

--- Roland.

    $ echo 'int main(void) { puts("Hello, world!"); return 0; }' > hello.c
    $ gcc -DFOO hello.c -o hello
    $ ./hello
    Hello, world!

The GNU getopt routines don't by default impose any requirements on the
order of option and non-option arguments.

--

 ** Please send on-topic followups by Usenet, not email **

The article I was responding to claimed, essentially, that

    gcc foo.c -o foo

would not work, while

    gcc -o foo foo.c

would.  The only difference between these two is the relative order of
option arguments (`-o foo') and non-option arguments (`foo.c'); and indeed,
traditional getopt() implementations require all option arguments to appear
before all non-option arguments.  (getopt() is the standard (POSIX, Single
Unix, etc.) function to parse command-line arguments in C programs.)
However, the GNU implementation of getopt() does not have this restriction
by default.  You can set the environment variable POSIXLY_CORRECT to enable
this restriction for GNU getopt(); but gcc itself doesn't use getopt() and
ignores this environment variable.

--

 ** Please send on-topic followups by Usenet, not email **

Quote:

>Hi, wonder if anyone can advice. I've got a C program with two (yes two!)
>main() functions. During compilation I want only want part to compile
>depending on what has been passed to gcc.

>I've heard that I should be able to do something like

>    #ifdef SECTION_1
>    int main(int argc, char *argv)
>    {
>            /* First version of main() */
>            .......
>    }
>    #endif

>    #ifdef SECTION_2
>    int main(int argc, char *argv)
>    {
>            /* Second version of main() */
>            .......
>    }
>    #endif

>and during compile I should be able to do something like
>    gcc -DSECTION_2 progname.c -o progname
>to compile SECTION_2 only but I've not been very successful. Any ideas?
>Thanks.

int
main( int argc, char** argv )
{
#ifdef SECTION_1
...
#endif
#ifdef SECTION_2
...
#endif

Quote:}

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