Problems linking libraries

[yaustar]

Hiya,

Tried compiling several demos and its all fine till I reach any that needs libraries (eg OpenGL).

Errors I get are:
Main.cpp     undefined reference to 'glViewport@16'
Main.cpp     undefined reference to 'glMatrixMode@4'
etc

I have tried linking them under
Project -> Build Options -> Linker (under both release and debug and root)

Also the code has

Code

#pragma comment(lib, "opengl32.lib")
#pragma comment(lib, "glu32.lib")

So I cant see whats wrong.... can someone give me a step by step guide in case I am missing anything stupid...

Thanks

[thomas]

Those are libraries you need to link with to build basic OpenGL applications.

Either add -lopengl32 -lglu32 to "other linker options", or add opengl32 and glu32 to link libraries on the left, or link against opengl32.dll and glu32.dll which are both found inside WINDOWS\system32.

[yaustar]

Those are libraries you need to link with to build basic OpenGL applications.

Either add -lopengl32 -lglu32 to "other linker options", or add opengl32 and glu32 to link libraries on the left, or link against opengl32.dll and glu32.dll which are both found inside WINDOWS\system32.

Ooooookay.... the -lopengl32 and -lglu32 in other linker options worked.... my next question is why and what does it actually do when you do that?

[rickg22]

-l is the GCC command to link a library. For some reason adding them to the linker libraries list didn't work in your case.... (weird)

[mandrav]

-l is the GCC command to link a library. For some reason adding them to the linker libraries list didn't work in your case.... (weird)

It's not exactly "weird"...
He used #pragmas to link the libraries. These only work in MS compilers...

[yaustar]

I did link them under Linker -> Link Libraries as well but that didn't work either.. I was wondering if it would be due to importing of options and settings from a VC++ 6.0 workspace...

I am also having similar problems with another set of libraries but since it is a custom built set, it may be better to ask the author instead.

[thomas]

Probably not. Adding them to link libraries does exactly the same thing as -lopengl32 -lglu32, except that you can select an full pathname with a GUI file selector. But then, linking is a black art, so no guarantees.

[rickg22]

Ok... let's see...

1) Search for the libraries you're linking, using windows xp's Find (in start menu). It may take a while, tho.
2) Make sure the directories where these files are located, are included in the "Linker directories".
3) Make sure the libraries are included in the "Link libraries".
4) Rebuild.

[yaustar]

1) Search for the libraries you're linking, using windows xp's Find (in start menu). It may take a while, tho.
> C:\Program Files\CodeBlocks\lib

2) Make sure the directories where these files are located, are included in the "Linker directories".
> Compile -> Compiler Settings -> GNU GCC Compiler -> Linker tab ->  C:\Program Files\CodeBlocks\lib

3) Make sure the libraries are included in the "Link libraries".
> Check

4) Rebuild.
> Still the same problem

[thomas]

Out of curiosity, does it work if you add absolute paths?
e.g.:
C:\Program Files\CodeBlocks\lib\opengl32.lib
C:\Program Files\CodeBlocks\lib\glu32.lib

[yaustar]

Relative or Absolute paths didn't work either... I haven't tried a 'clean' install of codeblocks through, I just installed the latest version over an older one... .could this be a cause?

edit changed have to haven't

[squizzz]

Which compiler are you actually trying to use...?
Half of the post in this thread suggest it's VC Toolkit (you use #pragmas, *.libs) , other ones that it might be GCC. ("the -lopengl32 and -lglu32 in other linker options worked....")
It's quite confusing.

[yaustar]

Sorry, I am using the GCC compiler, it's just the source is an example tutorial. I didn't know the #pragma was VC only

[squizzz]

Sorry, I am using the GCC compiler, it's just the source is an example tutorial. I didn't know the #pragma was VC only

Okay, as I understand "-lopengl32 -lglu32" solves your problems, but you want link libraries via GUI interface?
If so, you should add libopengl32.a and libglu32.a (you can locate these in MinGW /lib subdirectory) instead of opengl32.lib & glu32.lib.
It comes to any other lib as well, if you were linking foo.lib in your VC 6.0, you will link libfoo.a while using MinGW compiler.

Hope this solves your problem.
Greetz.

[mandrav]

Sorry, I am using the GCC compiler, it's just the source is an example tutorial. I didn't know the #pragma was VC only

Okay, as I understand "-lopengl32 -lglu32" solves your problems, but you want link libraries via GUI interface?
If so, you should add libopengl32.a and libglu32.a (you can locate these in MinGW /lib subdirectory) instead of opengl32.lib & glu32.lib.
It comes to any other lib as well, if you were linking foo.lib in your VC 6.0, you will link libfoo.a while using MinGW compiler.

Or just use foo as a link library and it will be replaced by C::B depending on the used compiler, i.e. libfoo.a vs foo.lib.