Empty Main

[Raj]

Could anyone tell me how to display "Hello World" in C++ without
writing anything inside main?i.e, main should not contain even a
single statement (no object creation or no cout or anything)

[Ivan Vecerina]

Re: Empty Main

"Raj" <raj.reshmi@gma il.com> wrote in message
news:1140593268 .885746.174340@ f14g2000cwb.goo glegroups.com.. .
: Could anyone tell me how to display "Hello World" in C++ without
: writing anything inside main?i.e, main should not contain even a
: single statement (no object creation or no cout or anything)

Have you studied the construction/destruction of global
objects yet ?


--
http://ivan.vecerina.com/contact/?subject=NG_POST <- email contact form

[Harry]

Re: Empty Main

Try the following:

#include <iostream>
using namespace std;

class t
{
public:
t(){ std::cout<<"Hel lo world!"<<std::e ndl; }
};

t _t;

int main()
{

}

This should work.

[Fred Zwarts]

Re: Empty Main

"Harry" <hapordigi@gmai l.com> wrote in message news:1140599038 .819812.7910@g1 4g2000cwa.googl egroups.com...[color=blue]
> Try the following:
>
> #include <iostream>
> using namespace std;
>
> class t
> {
> public:
> t(){ std::cout<<"Hel lo world!"<<std::e ndl; }
> };
>
> t _t;
>
> int main()
> {
>
> }
>
> This should work.[/color]

If have seen that this works on some platforms.
On other platforms, however, it failed because cout is also a static object
and the constructor of _t was called when cout had not yet been constructed.
In such cases I use printf.

Fred.Zwarts.

[Ivan Vecerina]

Re: Empty Main

"Fred Zwarts" <F.Zwarts@KVI.n l> wrote in message
news:dthkko$p74 $1@info.service .rug.nl...
:"Harry" <hapordigi@gmai l.com> wrote in message
news:1140599038 .819812.7910@g1 4g2000cwa.googl egroups.com...
:> Try the following:
:>
:> #include <iostream>
:> using namespace std;
:>
:> class t
:> {
:> public:
:> t(){ std::cout<<"Hel lo world!"<<std::e ndl; }
:> };
:>
:> t _t;
:>
:> int main()
:> {
:>
:> }
:>
:> This should work.
:
:If have seen that this works on some platforms.
:On other platforms, however, it failed because cout is also a static
object
:and the constructor of _t was called when cout had not yet been
constructed.
:In such cases I use printf.

The C++ standard requires the above to work, and most of today's
implementations will be compliant with respect to this (there is
a common/published trick for the standard library to ensure the
timely initialization of std::cout).

Ivan
--
http://ivan.vecerina.com/contact/?subject=NG_POST <- email contact form
Brainbench MVP for C++ <> http://www.brainbench.com

[Raj]

Re: Empty Main

Thanks a lot all of you..
I tried it and its working....
Thank you

[Csaba]

Re: Empty Main

"Raj" <raj.reshmi@gma il.com> wrote in news:1140593268 .885746.174340
@f14g2000cwb.go oglegroups.com:
[color=blue]
> Could anyone tell me how to display "Hello World" in C++ without
> writing anything inside main?i.e, main should not contain even a
> single statement (no object creation or no cout or anything)
>[/color]

---- begin hello.cxx ----
char *p = "Hellow, world";
---- end hello.cpp ----

Hey look, no main() at all !

Compile with one of:

g++ -E hello.cxx
g++ -S hello.cxx

( alas, g++ -c hello.cxx -o - doesn't seem to work )-:


Of course this prints some extraneous stuff, which can safely be ingnored
:-)

--
Life is complex, with real and imaginary parts.

[GB]

Re: Empty Main

Harry wrote:[color=blue]
> Try the following:
>
> #include <iostream>
> using namespace std;
>
> class t
> {
> public:
> t(){ std::cout<<"Hel lo world!"<<std::e ndl; }
> };
>
> t _t;
>
> int main()
> {
>
> }
>
> This should work.
>[/color]

A simpler approach that doesn't require defining a class is this:

#include <iostream>

std::ostream& s = std::cout << "Hello World\n";

int main()
{
}

[roberts.noah@gmail.com]

Re: Empty Main


Raj wrote:[color=blue]
> Thanks a lot all of you..
> I tried it and its working....
> Thank you[/color]

Yeah, it's great when people do your homework for you isn't it.

[Ron Natalie]

Re: Empty Main

Harry wrote:[color=blue]
> Try the following:
>
> #include <iostream>
> using namespace std;
>
> class t
> {
> public:
> t(){ std::cout<<"Hel lo world!"<<std::e ndl; }
> };
>
> t _t;
>
> int main()
> {
>
> }
>
> This should work.
>[/color]
_t is an improper symbol name. Leading underscores in
the global namespace are reserved to the implementation.

[Fred Zwarts]

Re: Empty Main

Related to this topic, consider the following program:

class t
{
public:
t() { std::cout<<"Hel lo world!"<<std::e ndl; }
~t() { std::cout<<"Goo dbye world!"<<std::e ndl; }
};

t T;

int main()
{

}

I understood from the discussion
that the C++ standard defines that the constructor of T is called after the construction of cout.
Does the C++ standard also tell that the destructor of T is called before the destruction of cout?

Regards,
Fred.Zwarts.