Can't link an external C dll

Florian

Hello,
I have trouble linking an external C dll into a QtCreator project.
In the library I'm using, I have a folder "include" containing some .h files, a folder "lib", containing only one .def file, and also have one .dll.

My .pro looks like that:

CONFIG+=console
CONFIG+=c++11
CONFIG-=app_bundle
CONFIG-=qt
  
DEF_FILE+="C:\MyLib\lib\MyLib.def"
  
INCLUDEPATH+=C:\MyLib\include
  
LIBS+=-LC:\MyLib\lib
  
SOURCES+=\
main.cpp
  
include(deployment.pri)
qtcAddDeployment()

However, at compilation time, I have a lot of errors : "LNK2001: unresolved external symbol ..."
These errors appear for the functions appearing in the .def file.

I don't know what else I can do... I have very few experience linking library in QtCreator.

Thanks for your help

Christopher

LIBS+=-LC:\MyLib\lib -lMyLib

You also have to tell the compiler to use the MyLiblibrary with -lMyLib argument

Florian

Thank you for your answer.

However, I don't have any .lib file. In the "lib" folder, all I have is a .def file.

If I add the line you mentioned, the compiler says: LNK1104: cannot open file 'MyLib.lib'

ad1170

Hello,

try to make the LIB from DEF File:

lib /machine:x86 /def:yourDef.def /out:yourlib.lib

(i use lib.exe from VisualStudio)

Regards

sneubert

Hi Florian,

the .def file contains the names of the exported function in the .dll.
To get a .lib for importing in you project as Christopher suggested you need the lib-Tool
from Microsoft Visual Studio.
Once you have Visual Studio you can open a "Visual Studio Command Prompt" and type

lib.exe /def:C:\MyLib\lib\MyLib.def /OUT:C:\MyLib\lib\MyLib.lib

Florian

Thank you very much to both of you, it's almost working perfectly.

Now I only have two warnings:

LNK4070: /OUT:Mylib.dll directive in .EXP differs from output filename 'debug\ProjectName.exe'; ignoring directive
And in red it's written: File not found: ProjectName.exp

I get MyLib.exp using lib.exe, that I put in the lib folder (I'm pretty sure it's not useful there), but it seems I also need a ProjectName.exp ?

The second warning is even more weird to me:
LNK4086: entrypoint '_mainCRTStartup' is not __stdcall with 12 bytes of arguments; image may not run

Any idea of what could be the problem?

EDIT: It seems to be okay now. I just remove the line "DEF_FILE+="C:\MyLib\lib\MyLib.def"" from my .pro, and everything seems to be working now :)

Thank you again,
Florian