dev-cpp-users

Re: [Dev-C++] Error using void main (void)

[Alfred P. R. <al...@ya...>]

Warnings are mostly ignorable, or nice if you like to write clean portable code.  main should always return an int as that's the exit value that the executable gives to DOS/Win/Linux upon completion.  Source should compile and run with a void main.  However, main's exit value will then always be 0 and therefore useless to test for a certain execution completion status.

Alexsandro Meireles <mei...@gm...> wrote:
Hi, all!
 
I tried to use the following expression in Dev-C++
 
void main (void)
 
The compiler give a warning message "output of main is not int". Something like that. Although it gives this warning it compilies well. Why this happens? Main should always have a return type?
 
Tks in advance!

-- 
Alexsandro Meireles 





Alfred P. Reaud
 

Re: [Dev-C++] Error using void main (void)

[Ray K. <kul...@wr...>]

Another thing to consider is that, as far as I know, while the return
*type* of a function defaults to int, the return *value* doesn't default
to anything in particular. If so, it might just return whatever value
happens to live in memory at a certain point, and if the value is
anything other than 0, the operating system will interpret that to mean
that the program terminated with an error.  (It's good form to
include the type specification and return statement, regardless.)

Per Westermark <pw...@ia...> wrote:
> Note that
>   main()
> is ONLY allowed for C programs, where a symbol without a declared data
> type defaults to int, i.e.
>   main()
> in reality means:
>   int main()
> in a C program.
> For C++ programs, you MUST actually use
>   int main()
> since the ISO C++ standard requires it. Yes, I know that g++ do accept  
> the
> lazy form and only emits "warning: ISO C++ forbids declaration of  
> `main=B4
> with no type" if warnings are enabled. However, don't assume something
> about how other compilers look at ISO compliance requirements!
> /Per W
> On Thu, 21 Apr 2005, Austin Scholze wrote:
>
>> also, I have found in dev-C++ that you may just use
>>
>> main()
>>
>> without actually initializing it and that it will exit at the end of  
>> the function.
>>   ----- Original Message -----
>>   From: Verne H. Bohlender
>>   To: Dev C++ ; Alfred P. Reaud
>>   Sent: Wednesday, April 20, 2005 9:48 PM
>>   Subject: Re: [Dev-C++] Error using void main (void)
>>
>>
>>   That's what it should say as it really should be
>>
>>   int main() or with all the other goodies inside the brackets.  If you  
>> read across it says"int main void for the two ( )'s for the void here!
>>
>>   Verne
>>       The GRIN Genius who knows nothing!
>>
>>     Warnings are mostly ignorable, or nice if you like to write clean  
>> portable code.  main should always return an int as that's the exit  
>> value that the executable gives to DOS/Win/Linux upon completion.   
>> Source should  compile and run with a void main.  However, main's exit  
>> value will then always be 0 and therefore useless to test for a certain  
>> execution completion status.
>>
>>     Alexsandro Meireles <mei...@gm...> wrote:
>>       Hi, all!
>>
>>       I tried to use the following expression in Dev-C++
>>
>>       void main (void)
>>
>>       The compiler give a warning message "output of main is not int".  
>> Something like that. Although it gives this warning it compilies well.  
>> Why this happens? Main should always have a return type?
>>
>>       Tks in advance!
>>
>>       --
>>       Alexsandro Meireles
>>
>>
>>
>>     Alfred P. Reaud

Re: [Dev-C++] Error using void main (void)

[Robert A. <ral...@gm...>]

Actually,

I believe that the ANSI standard allows main to just end without any
return code which isn't allowed for any other function declared to
return an int.  And as a special consideration for main it will return
'0' (zero) for you.

Actually.. a few web searches indicate that is C++ standard not C.  So
it looks like for C you are correct... what ever garbage happens to be
in the return register.

-Robert

On 4/21/05, Ray Kulhanek <kul...@wr...> wrote:
> Another thing to consider is that, as far as I know, while the return
> *type* of a function defaults to int, the return *value* doesn't default
> to anything in particular. If so, it might just return whatever value
> happens to live in memory at a certain point, and if the value is
> anything other than 0, the operating system will interpret that to mean
> that the program terminated with an error.  (It's good form to
> include the type specification and return statement, regardless.)
>=20
> Per Westermark <pw...@ia...> wrote:
> > Note that
> >   main()
> > is ONLY allowed for C programs, where a symbol without a declared data
> > type defaults to int, i.e.
> >   main()
> > in reality means:
> >   int main()
> > in a C program.
> > For C++ programs, you MUST actually use
> >   int main()
> > since the ISO C++ standard requires it. Yes, I know that g++ do accept
> > the
> > lazy form and only emits "warning: ISO C++ forbids declaration of
> > `main=3DB4
> > with no type" if warnings are enabled. However, don't assume something
> > about how other compilers look at ISO compliance requirements!
> > /Per W
> > On Thu, 21 Apr 2005, Austin Scholze wrote:
> >
> >> also, I have found in dev-C++ that you may just use
> >>
> >> main()
> >>
> >> without actually initializing it and that it will exit at the end of
> >> the function.
> >>   ----- Original Message -----
> >>   From: Verne H. Bohlender
> >>   To: Dev C++ ; Alfred P. Reaud
> >>   Sent: Wednesday, April 20, 2005 9:48 PM
> >>   Subject: Re: [Dev-C++] Error using void main (void)
> >>
> >>
> >>   That's what it should say as it really should be
> >>
> >>   int main() or with all the other goodies inside the brackets.  If yo=
u
> >> read across it says"int main void for the two ( )'s for the void here!
> >>
> >>   Verne
> >>       The GRIN Genius who knows nothing!
> >>
> >>     Warnings are mostly ignorable, or nice if you like to write clean
> >> portable code.  main should always return an int as that's the exit
> >> value that the executable gives to DOS/Win/Linux upon completion.
> >> Source should  compile and run with a void main.  However, main's exit
> >> value will then always be 0 and therefore useless to test for a certai=
n
> >> execution completion status.
> >>
> >>     Alexsandro Meireles <mei...@gm...> wrote:
> >>       Hi, all!
> >>
> >>       I tried to use the following expression in Dev-C++
> >>
> >>       void main (void)
> >>
> >>       The compiler give a warning message "output of main is not int".
> >> Something like that. Although it gives this warning it compilies well.
> >> Why this happens? Main should always have a return type?
> >>
> >>       Tks in advance!
> >>
> >>       --
> >>       Alexsandro Meireles
> >>
> >>
> >>
> >>     Alfred P. Reaud
>=20
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Re: [Dev-C++] Error using void main (void)

[Verne H. B. <ve...@sy...>]

That's what it should say as it really should be=20

int main() or with all the other goodies inside the brackets.  If you =
read across it says"int main void for the two ( )'s for the void here!

Verne=20
    The GRIN Genius who knows nothing!

  Warnings are mostly ignorable, or nice if you like to write clean =
portable code.  main should always return an int as that's the exit =
value that the executable gives to DOS/Win/Linux upon completion.  =
Source should compile and run with a void main.  However, main's exit =
value will then always be 0 and therefore useless to test for a certain =
execution completion status.

  Alexsandro Meireles <mei...@gm...> wrote:
    Hi, all!

    I tried to use the following expression in Dev-C++

    void main (void)

    The compiler give a warning message "output of main is not int". =
Something like that. Although it gives this warning it compilies well. =
Why this happens? Main should always have a return type?

    Tks in advance!

    --=20
    Alexsandro Meireles=20



  Alfred P. Reaud

   

Re: [Dev-C++] Error using void main (void)

[Austin S. <Aus...@co...>]

also, I have found in dev-C++ that you may just use

main()

without actually initializing it and that it will exit at the end of the =
function.
  ----- Original Message -----=20
  From: Verne H. Bohlender=20
  To: Dev C++ ; Alfred P. Reaud=20
  Sent: Wednesday, April 20, 2005 9:48 PM
  Subject: Re: [Dev-C++] Error using void main (void)


  That's what it should say as it really should be=20

  int main() or with all the other goodies inside the brackets.  If you =
read across it says"int main void for the two ( )'s for the void here!

  Verne=20
      The GRIN Genius who knows nothing!

    Warnings are mostly ignorable, or nice if you like to write clean =
portable code.  main should always return an int as that's the exit =
value that the executable gives to DOS/Win/Linux upon completion.  =
Source should compile and run with a void main.  However, main's exit =
value will then always be 0 and therefore useless to test for a certain =
execution completion status.

    Alexsandro Meireles <mei...@gm...> wrote:
      Hi, all!

      I tried to use the following expression in Dev-C++

      void main (void)

      The compiler give a warning message "output of main is not int". =
Something like that. Although it gives this warning it compilies well. =
Why this happens? Main should always have a return type?

      Tks in advance!

      --=20
      Alexsandro Meireles=20



    Alfred P. Reaud

     

Re: [Dev-C++] Error using void main (void)

[Per W. <pw...@ia...>]

Note that
  main()
is ONLY allowed for C programs, where a symbol without a declared data
type defaults to int, i.e.
  main()
in reality means:
  int main()
in a C program.

For C++ programs, you MUST actually use
  int main()
since the ISO C++ standard requires it. Yes, I know that g++ do accept the
lazy form and only emits "warning: ISO C++ forbids declaration of `main=B4
with no type" if warnings are enabled. However, don't assume something
about how other compilers look at ISO compliance requirements!

/Per W

On Thu, 21 Apr 2005, Austin Scholze wrote:

> also, I have found in dev-C++ that you may just use
>
> main()
>
> without actually initializing it and that it will exit at the end of the =
function.
>   ----- Original Message -----
>   From: Verne H. Bohlender
>   To: Dev C++ ; Alfred P. Reaud
>   Sent: Wednesday, April 20, 2005 9:48 PM
>   Subject: Re: [Dev-C++] Error using void main (void)
>
>
>   That's what it should say as it really should be
>
>   int main() or with all the other goodies inside the brackets.  If you r=
ead across it says"int main void for the two ( )'s for the void here!
>
>   Verne
>       The GRIN Genius who knows nothing!
>
>     Warnings are mostly ignorable, or nice if you like to write clean por=
table code.  main should always return an int as that's the exit value that=
 the executable gives to DOS/Win/Linux upon completion.  Source should comp=
ile and run with a void main.  However, main's exit value will then always =
be 0 and therefore useless to test for a certain execution completion statu=
s.
>
>     Alexsandro Meireles <mei...@gm...> wrote:
>       Hi, all!
>
>       I tried to use the following expression in Dev-C++
>
>       void main (void)
>
>       The compiler give a warning message "output of main is not int". So=
mething like that. Although it gives this warning it compilies well. Why th=
is happens? Main should always have a return type?
>
>       Tks in advance!
>
>       --
>       Alexsandro Meireles
>
>
>
>     Alfred P. Reaud
>
>