Date: 29 Nov 2005 08:33:25 -0500 From: Lowell Gilbert <freebsd-questions-local@be-well.ilk.org> To: Mamta BANSAL <mamta.bansal@st.com> Cc: freebsd-questions@freebsd.org Subject: Re: questions about gcc options Message-ID: <441x0zlgt6.fsf@be-well.ilk.org> In-Reply-To: <438AAD0F.90205@st.com> References: <438AAD0F.90205@st.com>
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Mamta BANSAL <mamta.bansal@st.com> writes:
> Hello
> for a c code i am using gcc compiler.
> i have doubt using -c option.
> for a c code the code compiles (without error ) with -c option even if
> i don't provide prior declaration of function.
> i mean i have try.c
> //*******************
>
> void my_func( ){
> call_to_undeclared_func( );
> }
> //********************
> i do : gcc -c try.c , it works.
> is it the correct behaviour , i mean should it not ask for atleast
> declearation of call_to_undeclared_func( );
>
> like if my make the same as try.cpp then usen use the same command it
> gives the foll. error.:
>
> try.cpp: In function `void my_func()':
> try.cpp:2: implicit declaration of function `int
> call_to_undeclared_func(...)'
> which i feel is expected behaviour.
That doesn't require a diagnostic in C, but it does in C++.
If you want the diagnostics anyway, use the
-Wimplicit-function-declaration flag to the compiler. Or -Wall, which
adds a pretty extensive set of non-required warnings. See the gcc
manual if you want more information.
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