dev-cpp-users Mailing List for Dev-C++

One note.

Since globally declared static variables are only accessible in a single
compilation unit, they are normally not declared in any include file. If
they are declared in an include file, every C or C++ file that included
the file would get it's own copy of a static variable.

/Per W

On Sun, 12 Oct 2003, xRxIxPx wrote:

> In general, you should only have const, static and extern variable
> declarations in your header files, and in ONE .cpp file the definition for
> your extern variables.
>

At 08:15 AM 10/12/2003 -0400, Matthews wrote:
>Guard statements are lines like these in your header files:
>
>#ifndef FOOHEADER_H
>#define FOOHEADER_H
>
>int foo;
>char *foostring;
>//...

That should not happen! If you include this header in two different compile 
units (means .cpp files), your global objects will be defined in 2 object 
files making the linker bailing out errornously.
In general, you should only have const, static and extern variable 
declarations in your header files, and in ONE .cpp file the definition for 
your extern variables.


>#endif
>
>Then if two files include foo.h, it won't be recompiled because FOOHEADER_H
>has already been defined.



Only true for one compile unit.

Better have:
#ifndef FOOHEADER_H
#define FOOHEADER_H

extern int foo;
extern char *foostring;
//...
#endif

foo1.cpp
#include "fooheader.h"

foo2.cpp
#include "fooheader1.h"

int foo=631;
char* foostring=0;


Cheers.

Hello all,


Does anyone have compiled a libsigC++ 1.0.x package for DevCpp
(a devpak) or has makefile adapted to DevCpp, it is a bit a hell to 
compile from the standard tazr.gz archive

Thanks in advance 

Matthews <dem...@uw...> wrote:

> Guard statements are lines like these in your header files:
>=20
> #ifndef FOOHEADER_H
> #define FOOHEADER_H
>=20
> int foo;
> char *foostring;
> //...
>=20
> #endif
>=20
> Then if two files include foo.h, it won't be recompiled because FOOHEAD=
ER_H
> has already been defined.

I think this answer is confusing to all the newbees out there...

First point:
Of course the header file will be compiled-in with each .cpp/.c that incl=
udes=20
it. If you check the makefile, each .cpp is compiled by it self and there=
 is=20
no way for the compiler to know if the header has already been included a=
nd=20
thus compiled...

Second point:
The guard statements mentioned prevent the same header from being include=
d=20
more than once during the compilation of _one_ .cpp=B4. Consider the foll=
owing:

file1.h

#include "file2.h"

....

file2.h

#include "file1.h"

...


Without the guard stetements file1.h would include file2.h whitch include=
s=20
file1.h...=20

Third point:
The example .h-file above contains definitions of variables. If you inclu=
de=20
this file the variables foo and foostring would be instanciated as local =
(file-
scope) in each .cpp where the .h is included. Not very useful?! To make g=
lobal=20
variables declare as _external_ in header fil and move the instansiation =
to=20
the .cpp file.

Regards, Paul.

Chris Sroka wrote:

>I want to draw a bitmap (from a file on disk) into a part of the dialog 
>box. I have trawled the msdn.microsoft.com pages and haven't found a way 
>to do this successfully.
>
>Any suggestions?
>
>Thanks
>Chris S

Normally, you would draw a bitmap in response to the WM_PAINT or 
WM_ERASEBKGND messages, which pass a handle to the Device Context of the 
window (HDC).

Use the DC functions to draw the bitmap (BitBlt, etc.) .

If you don't have it already, download the Windows Developers' Reference 
(SDK help) from Microsoft. It is essential for Windows programming.

Kev.

> I found DEV to be excellent for learning C++, but if you then move to visual 
> studio and microsoft's version of C++ (I am exaggerating) then it can be a 
> little confusing with templates.

Not so much with MSVC7.1. So far, there hasn't been found so much
problems in it (including in the templates issues).

But, under any circumstances, I don't recommend using any of M$
products.

> But do not worry, you will not go wrong. And post your questions to the 
> mailing list - I need to get better at C++ also!!! (too much cross-language 
> work!).

So do I (after neerly a decade of C++ programming).

Regards,
--Hossein
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I have a dialog box defined manually in a resource script file:=20

............
ID_DIALOG_2 DIALOG 0, 0, 250, 90
STYLE WS_VISIBLE | WS_SYSMENU | WS_MINIMIZEBOX | WS_MAXIMIZEBOX | =
WS_POPUP | WS_CAPTION | DS_MODALFRAME
CAPTION "About"
FONT 8,"Helv"
BEGIN
    DEFPUSHBUTTON   "OK",ID_OK,180,10,50,14,WS_GROUP
END
.............


I want to draw a bitmap (from a file on disk) into a part of the dialog =
box. I have trawled the msdn.microsoft.com pages and haven't found a way =
to do this successfully.=20

Any suggestions?=20

Thanks=20
Chris S

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