Re: Linking problem: IsWindowVisible

Re: Linking problem: IsWindowVisible

[Øystein O Johansen]

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Well, thanks to Jeff, my program works now. Thanks for the help and thanks
for the interesting discussion.

Thanks all,
Øystein



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Re: Linking problem: IsWindowVisible

[Axel Riese]

> > Anyway, adding -mwindows or -luser32
> > should solve the problem.
> 
> IIRC the undefined symbol was 'IsWindowVisible', which is a symptom of a
> different problem.  That symbol isn't defined in any Win32 library...
> 'IsWindowVisible@4' is.

Oops, I correct the above: Anyway, adding -mwindows or -luser32 to the
flags and #include <windows.h> to the code should solve the problem.

- Axel

=======================================================================
Axel Riese
Research Institute for Symbolic Computation
J. Kepler University Linz                     Tel: +43 (0)732 2468 9939
Altenbergerstrasse 69                         Fax: +43 (0)732 2468 9930
A-4040 Linz                      e-Mail: Axel.Riese@risc.uni-linz.ac.at
Austria              http://www.risc.uni-linz.ac.at/people/ariese/home/
=======================================================================

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Re: Linking problem: IsWindowVisible

[Jeff Sturm]

Axel Riese wrote:
> Yes, clear. But I have my doubts that one can get an undefined reference
> due to a missing declaration.

Sure you can, because the __stdcall modifier alters the linkage name of
the symbol.

> Anyway, adding -mwindows or -luser32
> should solve the problem.

IIRC the undefined symbol was 'IsWindowVisible', which is a symptom of a
different problem.  That symbol isn't defined in any Win32 library...
'IsWindowVisible@4' is.

-- 
Jeff Sturm
jsturm@sigma6.com

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Re: Linking problem: IsWindowVisible

[Chris Faylor]

On Wed, Mar 15, 2000 at 03:57:56PM +0100, Axel Riese wrote:
>> > Hm, in this case you should have problems at compile time, not at
>> > link time, shouldn't you ?
>> 
>> Not necessarily.  In the absence of a declaration, C will guess "int
>> IsWindowVisible()", which in this case is wrong.
>> 
>> BTW you can catch such problems by compiling with -Wall:
>
>Yes, clear. But I have my doubts that one can get an undefined reference
>due to a missing declaration. Anyway, adding -mwindows or -luser32
>should solve the problem.

Your doubts are wrong.  If you haven't declared the function correctly
this is exactly what you'll get.

cgf

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Re: Linking problem: IsWindowVisible

[Axel Riese]

> > Hm, in this case you should have problems at compile time, not at
> > link time, shouldn't you ?
> 
> Not necessarily.  In the absence of a declaration, C will guess "int
> IsWindowVisible()", which in this case is wrong.
> 
> BTW you can catch such problems by compiling with -Wall:

Yes, clear. But I have my doubts that one can get an undefined reference
due to a missing declaration. Anyway, adding -mwindows or -luser32
should solve the problem.

- Axel

=======================================================================
Axel Riese
Research Institute for Symbolic Computation
J. Kepler University Linz                     Tel: +43 (0)732 2468 9939
Altenbergerstrasse 69                         Fax: +43 (0)732 2468 9930
A-4040 Linz                      e-Mail: Axel.Riese@risc.uni-linz.ac.at
Austria              http://www.risc.uni-linz.ac.at/people/ariese/home/
=======================================================================

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Re: Linking problem: IsWindowVisible

[Jeff Sturm]

Axel Riese wrote:
> > > Yes, I worked that out by self. But I still get undefined
> > > reference to 'IsWindowVisible' ?
> >
> > You may be missing a declaration for IsWindowVisible.  Does the source
> > file have #include <windows.h> anywhere?
>
> Hm, in this case you should have problems at compile time, not at
> link time, shouldn't you ?

Not necessarily.  In the absence of a declaration, C will guess "int
IsWindowVisible()", which in this case is wrong.

BTW you can catch such problems by compiling with -Wall:

jcs.c:4: warning: implicit declaration of function `IsWindowVisible'

-- 
Jeff Sturm
jsturm@sigma6.com

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Re: Linking problem: IsWindowVisible

[Axel Riese]

> > Yes, I worked that out by self. But I still get undefined
> > reference to 'IsWindowVisible' ?
> 
> You may be missing a declaration for IsWindowVisible.  Does the source
> file have #include <windows.h> anywhere?

Hm, in this case you should have problems at compile time, not at
link time, shouldn't you ?

- Axel

=======================================================================
Axel Riese
Research Institute for Symbolic Computation
J. Kepler University Linz                     Tel: +43 (0)732 2468 9939
Altenbergerstrasse 69                         Fax: +43 (0)732 2468 9930
A-4040 Linz                      e-Mail: Axel.Riese@risc.uni-linz.ac.at
Austria              http://www.risc.uni-linz.ac.at/people/ariese/home/
=======================================================================

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Re: Linking problem: IsWindowVisible

[Jeff Sturm]

Earnie Boyd wrote:
> Use the -mwindows switch.  It'll add the necessary libraries to the build.

True... although with -mwindows you lose the text console, which is not
always what you want (I always print debug messages to stderr... but
hey, I'm a Unix guy at heart).

-- 
Jeff Sturm
jsturm@sigma6.com

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Re: Linking problem: IsWindowVisible

[Jeff Sturm]

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Øystein O Johansen wrote:
> Yes, I worked that out by self. But I still get undefined
> reference to 'IsWindowVisible' ?

You may be missing a declaration for IsWindowVisible.  Does the source
file have #include <windows.h> anywhere?

(Win32 API functions must be declared with __stdcall, that's where the
@4 comes from).

-- 
Jeff Sturm
jsturm@sigma6.com

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Re: Linking problem: IsWindowVisible

[Earnie Boyd]

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--- Øystein_O_Johansen <OJOHANS@statoil.com> wrote:
> >> I got a program thet uses IsWindowVisible. I think this is a
> >> standard Win API function. But what to link it with? -lgdi32 fails.
> 
> > According to MS's online docu, it's -luser32.
> 

Use the -mwindows switch.  It'll add the necessary libraries to the build.

 

=====
---
   Earnie Boyd: < mailto:earnie_boyd@yahoo.com >
            __Cygwin: POSIX on Windows__
Cygwin Newbies: < http://www.freeyellow.com/members5/gw32/index.html >
           __Minimalist GNU for Windows__
  Mingw32 List: < http://www.egroups.com/group/mingw32/ >
    Mingw Home: < http://www.mingw.org/ >

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Re: Linking problem: IsWindowVisible

[Axel Riese]

> Yes, I worked that out by self. But I still get undefined
> reference to 'IsWindowVisible' ?
> 
> I even tried to remake the import library file (libuser32.a) from
> the user32.def file and the user32.dll. Yes, user32.def does
> include IsWindowVisible@4 in line 345, but it still doesn't link.

Sounds strange. How do you invoke gcc for compiling and linking ?

- Axel

=======================================================================
Axel Riese
Research Institute for Symbolic Computation
J. Kepler University Linz                     Tel: +43 (0)732 2468 9939
Altenbergerstrasse 69                         Fax: +43 (0)732 2468 9930
A-4040 Linz                      e-Mail: Axel.Riese@risc.uni-linz.ac.at
Austria              http://www.risc.uni-linz.ac.at/people/ariese/home/
=======================================================================

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Re: Linking problem: IsWindowVisible

[Øystein O Johansen]

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>> I got a program thet uses IsWindowVisible. I think this is a
>> standard Win API function. But what to link it with? -lgdi32 fails.

> According to MS's online docu, it's -luser32.

Yes, I worked that out by self. But I still get undefined
reference to 'IsWindowVisible' ?

I even tried to remake the import library file (libuser32.a) from
the user32.def file and the user32.dll. Yes, user32.def does
include IsWindowVisible@4 in line 345, but it still doesn't link.

???

-Øystein



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Re: Linking problem: IsWindowVisible

[Axel Riese]

> I got a program thet uses IsWindowVisible. I think this is a
> standard Win API function. But what to link it with? -lgdi32 fails.

According to MS's online docu, it's -luser32.

- Axel


=======================================================================
Axel Riese
Research Institute for Symbolic Computation
J. Kepler University Linz                     Tel: +43 (0)732 2468 9939
Altenbergerstrasse 69                         Fax: +43 (0)732 2468 9930
A-4040 Linz                      e-Mail: Axel.Riese@risc.uni-linz.ac.at
Austria              http://www.risc.uni-linz.ac.at/people/ariese/home/
=======================================================================

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Linking problem: IsWindowVisible

[Øystein O Johansen]

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Hi!
I got a program thet uses IsWindowVisible. I think this is a
standard Win API function. But what to link it with? -lgdi32 fails.

undefined reference to 'IsWindowVisible'

-Øystein



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