🚀 go-pugleaf

On Tue, 04 Apr 2000 18:01:47 -0600, Jeff Shipman <shippy@cs.nmt.edu> wrote:
>Sorry if this is not the correct newsgroup to post to. I
>wasn't sure which one would be right. My problem is that
>I'm compiling my program with the -pedantic and -ansi
>flags and I get the following warning:
>
>cb.c:348: warning: implicit declaration of function `gethostname'
>
>I am including unistd.h and it compiles just fine if I
>leave out those two flags. Is it because gethostname()
>is not ANSI C?

Not quite.  It's true that this function is not ANSI C, but then again, neither
is the <unistd.h> header. What is happening is that you are getting only the
minimal set of identifiers out of this POSIX header; you need to add a feature
selection macro something like _XOPEN_SOURCE to enable addtional things that
are not in POSIX.  

In other words, in additon to supressing extensions in ANSI C headers and
ensuring that the compiler accepts all ANSI C programs, the -ansi option
also suppresses extensions in other headers, allowing you to use feature
selection macros to enable specific interface standards.

-- 
#exclude <windows.h>

Jeff Shipman wrote:
> 
> Sorry if this is not the correct newsgroup to post to. I
> wasn't sure which one would be right. My problem is that
> I'm compiling my program with the -pedantic and -ansi
> flags and I get the following warning:
> 
> cb.c:348: warning: implicit declaration of function `gethostname'
> 
> I am including unistd.h and it compiles just fine if I
> leave out those two flags. Is it because gethostname()
> is not ANSI C? If so, I'm also using a lot of GTK code
> in there, it's not ANSI C, and the compiler doesn't
> seem to mind...is there something I'm not getting? Thanks
> in advance.

$ uname -a
SunOS saltlake 5.6 Generic_105181-13 sun4u sparc
$ man gethostbyname | grep '#include'
Reformatting page.  Wait... done
     #include <netdb.h>

gethostbyname() is prototyped in netdb.h, not unistd.h, on Solaris (if
I were at home I would tell you that Linux, FreeBSD, NetBSD, OpenBSD
and SunOS 4.1.4 as well...but for now all I can say is I'm 99% sure
about those). The warning gcc prints means that you are calling
a function (gethostbyname()) without a prototype first, which means the
return and argument types must be inferred (hence 'implicit decl').

Include <netdb.h> in your cb.c, and you should be good to go.

> --
> +-----------------------------------------------------+
> | Jeff "Shippy" Shipman     E-Mail: shippy@cs.nmt.edu |
> | Computer Science Major    ICQ: 1786493              |
> | New Mexico Institute of Mining and Technology       |
> | Homepage: http://www.nmt.edu/~shippy                |
> +-----------------------------------------------------+


-- 
Nathan Dorfman <nathan@rtfm.net>                [http://www.rtfm.net]
"The light at the end of the tunnel is the headlight of an approaching
train." --/usr/games/fortune