Re: variable length function

[Steve Graegert <graegerts@gmail.com>]

On 6/15/05, Ankit Jain <ankitjain1580@yahoo.com> wrote:
> Hi
> 
> thanks for help

You're welcome.

> Well then i am just trying to clear my concept again.
> 
> main()
> {
>         printf("This is main");
> }
> 
> now this simple function main according to this
> discussion will return a int value.......Am i
> right....but is it true with any compiler?

This is true for most cases, although warnings may be issued.  In
practice, specifying a return type is a __very__ good idea.
 
> another thing........... if it returns a int value and
> we have not returned any value explicitly.........then
> what is the value returned ....as far as i know its a
> non-zero value. but then what will that mean.....?

It __may__ return a non-zero value.  If not, one can not predict the
actual value, it's random.  Under normal circumstances a non-zero
return value indicates a program error and can be used to specify its
types.

> --- Steve Graegert <graegerts@gmail.com> wrote:
> 
> > On 6/15/05, Glynn Clements
> > <glynn@gclements.plus.com> wrote:
> > >
> > > Steve Graegert wrote:
> > >
> > > > > also, if what is the default return type and
> > value of
> > > > > main function in C in gcc, ansi C and turbo C?
> > >
> > > > Question 4:
> > > > ISO C99 suggests the return type of main() to be
> > of type int.  There
> > > > is a never ending debate among some
> > professionals whether void is
> > > > equally legal.  Some compilers behave like ANSI
> > C that allows
> > > > declaration of type void but return int
> > implicitly.  In other words:
> > > > stick to int.
> > >
> > > The value returned from main is used as the
> > process' exit code. If you
> > > declare main() as returning void, and return from
> > it, the process is
> > > likely to have a random exit code (e.g. whatever
> > happens to be in the
> > > EAX register upon return from main()).
> >
> > Yes, another important issue.  The most reliable way
> > to return a valid
> > and correct value I am aware of is returning a value
> > explicitly.
> > You're right. just declaring int does not imply the
> > return code to be
> > the expected one, though being valid.  It is __not__
> > guaranteed that
> > the return type is not some random integer value
> > unless it is returned
> > explicitly.
> >
> > Another point that comes to mind are compilers with
> > distinct calling
> > conventions for int and void functions and job
> > control for example.
> > This can cause headaches when main() does not push a
> > return value on
> > the stack, as being the case with void, and the
> > caller tries to pop an
> > int which obviously is not found.  It __may__ lead
> > to subtle crashes
> > later on.
> >
> >
> > Kind Regards
> >
> >     \Steve
> >
> > --
> >
> > Steve Graegert <graegerts@gmail.com> ||
> > <http://www.technologies.de/~sg/>
> > Independent Software Consultant {C/C++ && Java &&
> > .NET}
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> 
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