pragma once

[Jacob Jensen]

Hi

I have a problem creating C++ code that is multiplatform compilable. My
problem is using the "#pragma once" directive which can be used by microsoft
Visual Studio pre-compiler but which gives warnings when used by gcc for
example. I would like to use it when compiling with Visual C++ compiler, but
how can I create a smart macro or something, so that it is truly ignored
when compiler with gcc. I have tried the following which actually dose not
serve my wish:

1-
#ifdef VISUAL_STUDIO_C OMPILER
#define MY_ONCE once
#else
#define MY_ONCE
#endif

and then to use it I simply type:
#pragma MY_ONCE

But this still gives a warning when compiled with gcc with the -Wall option
given.

2-
In a pragma_once.h file I type the following
#ifdef VISUAL_STUDIO_C OMPILER
#pragma once
#endif

And then whenever i need it I include pragma_once.h. The problem with this
is that it does not work, since pragma once directive is only effective for
the file it is located in, in this case pragma_once.h

3-
I do not have any other ideas but define a macro in some way as below:
#ifdef VISUAL_STUDIO_C OMPILER
#define PRAGMA_ONCE "#pragma once"
#else
#define PRAGMA_ONCE
#endif

but this does not compile, and I found it impossible to compile it with
similar structures.

Dont use microsoft specific things

Use
-----------------
#ifndef __MY_HEADER_FIL E_H__
#define __MY_HEADER_FIL E_H__

// my code here

#endif // __MY_HEADER_FIL E_H__
-----------------
instead of
-----------------
#pragma once

// my code here
-----------------

[Jacob Jensen]

But I want to use the pragma once directive with my microsoft compiler. Is
there no other option in to your knowledge?

Thank you again in advance
Jacob

"<- Chameleon ->" <ch******@hotma il.NOSPAM.com> wrote in message
news:c4******** **@nic.grnet.gr ...

Dont use microsoft specific things

Use
-----------------
#ifndef __MY_HEADER_FIL E_H__
#define __MY_HEADER_FIL E_H__

// my code here

#endif // __MY_HEADER_FIL E_H__
-----------------
instead of
-----------------
#pragma once

// my code here
-----------------

[Jacob Jensen]

But I want to use the pragma once directive with my microsoft compiler. Is
there no other option in to your knowledge?

Thank you again in advance
Jacob

"<- Chameleon ->" <ch******@hotma il.NOSPAM.com> wrote in message
news:c4******** **@nic.grnet.gr ...

Dont use microsoft specific things

Use
-----------------
#ifndef __MY_HEADER_FIL E_H__
#define __MY_HEADER_FIL E_H__

// my code here

#endif // __MY_HEADER_FIL E_H__
-----------------
instead of
-----------------
#pragma once

// my code here
-----------------

> But I want to use the pragma once directive with my microsoft compiler. Is

there no other option in to your knowledge?

in this case try this: (_MSC_VER)
I think I saw it inside gl.h (OpenGL header)
UNTESTED

----------------- #ifdef _MSC_VER #pragma once #endif
// my code here
-----------------

> But I want to use the pragma once directive with my microsoft compiler. Is

there no other option in to your knowledge?

in this case try this: (_MSC_VER)
I think I saw it inside gl.h (OpenGL header)
UNTESTED

----------------- #ifdef _MSC_VER #pragma once #endif
// my code here
-----------------

[Heinz Ozwirk]

"Jacob Jensen" <ja************ ***********@yah oo.co.uk> schrieb im Newsbeitrag news:nC******** ******@news.get 2net.dk...
: But I want to use the pragma once directive with my microsoft compiler. Is
: there no other option in to your knowledge?

If you really want to use #pragma once, do it as Microsoft does:

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

HTH
Heinz

[Heinz Ozwirk]

"Jacob Jensen" <ja************ ***********@yah oo.co.uk> schrieb im Newsbeitrag news:nC******** ******@news.get 2net.dk...
: But I want to use the pragma once directive with my microsoft compiler. Is
: there no other option in to your knowledge?

If you really want to use #pragma once, do it as Microsoft does:

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

HTH
Heinz

[Julie]

"<- Chameleon ->" wrote:

Use
-----------------
#ifndef __MY_HEADER_FIL E_H__
#define __MY_HEADER_FIL E_H__

Double-underscore identifiers are reserved for implementation purposes. Use
something like:

#define MY_HEADER_FILE_ H

instead.

[Julie]

"<- Chameleon ->" wrote:

Use
-----------------
#ifndef __MY_HEADER_FIL E_H__
#define __MY_HEADER_FIL E_H__

Double-underscore identifiers are reserved for implementation purposes. Use
something like:

#define MY_HEADER_FILE_ H

instead.