how to fix " Missing argument to '-L' " error ?

[Ahti]

@Eddy lol it still gives those 3 errors :(

[Eddy]

Good to see it's funny to you ;-)

Can you edit the link to you image or just copy the text here? We cannot see the image in your previous post.
You can use an image provider to show it to us by following this topic
There is still a problem with the uploading of image in the Qt forum. The admins are working on it though.

Edit : did you check the hint from @koahnig ?

[Ahti]

@Eddy see i edited the post

changing from && to $$ ? yes i did that but now i am gettings those errors

note the problem is with those Dll files i know it because when i delete them and run my project it works.

[Eddy]

why do you have those 2 lines?

win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Dll/ -ldxva2
win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Library/ -ldxva2

Is one of them not enough?
The Dll path seems redundant since you don't use it further on

[Ahti]

@Eddy

Okay removed everything except :

win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Dll/ -ldxva2

but still getting those 3 errors

I use that Dll file for getting some windows functions that i need in my project.
functions like :
GetDesktopWindow();
MonitorFromWIndow();
GetCurrentBrightness();
etc

[Eddy]

what is in your $$PWD/Dll/ folder?

[koahnig]

@Ahti said in how to fix " Missing argument to '-L' " error ?:

@Eddy

Okay removed everything except :

win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Dll/ -ldxva2

but still getting those 3 errors

I use that Dll file for getting some windows functions that i need in my project.
functions like :
GetDesktopWindow();
MonitorFromWIndow();
GetCurrentBrightness();
etc

The problem ist that this is only working for release. Therefore, you need to be sure that you are in release mode.
Also sometimes it is good to rerun qmake and possibly rebuild your libraries.

[Ahti]

@Eddy

3 windows dll files

dxva2.dll, dxva264.dll and user32.dll

[koahnig]

@Ahti said in how to fix " Missing argument to '-L' " error ?:

@Eddy

3 windows dll files

dxva2.dll, dxva264.dll and user32.dll

no libs with those file names?
The dlls are used during run time, but while linking you need to have the libs created together with the dlls there.

[Ahti]

@koahnig

now i got the libs but still getting that error :(

[koahnig]

@Ahti said in how to fix " Missing argument to '-L' " error ?:

@koahnig

now i got the libs but still getting that error :(

What is the actual error message with your current configuration?
Probably it would be good also to post the current .pro file.

[Ahti]

@koahnig

those three errors that i already mentioned.

my new pro file:

#-------------------------------------------------
#
# Project created by Ahtisham 2016-08-16T13:18:59
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = testMyProject
TEMPLATE = app


SOURCES += main.cpp\
        eyecare.cpp \
    others.cpp

HEADERS  += eyecare.h \
    others.h

FORMS    += eyecare.ui

RESOURCES += \
    images.qrc


win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Dll/ -ldxva2
win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Library/ -ldxva2
else:win32:CONFIG(debug,debug|release): LIBS += -L$$PWD/Library/ -ldxva2
else:unix: LIBS += -L$$PWD/Library/ -ldxva2

INCLUDEPATH += $$PWD/Library
DEPENDPATH += $$PWD/Library

win32:CONFIG(release, debug|release): LIBS += -L$$PWD/Library/ -luser32
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/Library/ -luser32
else:unix: LIBS += -L$$PWD/Library/ -luser32

INCLUDEPATH += $$PWD/Library
DEPENDPATH += $$PWD/Library

DISTFILES +=

[koahnig]

@Ahti

Which means that the stubs in the lib-file are missing?
Do you have the import and export keyword handled correctly?

The dll and the stub-lib are generâted with the same tool chain?

[Ahti]

@koahnig what do you mean by "stubs in the lib-file" what is that ? i don't know anything about that. I just copied all the required dll and lib files from the system32 to Dll and Library folders of my project respectively. And what is import and export keyword ?

I am creating this app just to let user change screen brightness and for that i need to use windows API and that is why i need those dll and lib files.

have a look:

https://msdn.microsoft.com/en-us/library/windows/desktop/dd692939(v=vs.85).aspx

goto the link and see at the end in "Requirements" heading it clearly mentions which library and dll files you need to include in order to use that specific windows api function.

[koahnig]

@Ahti

When creating a dll you will also create a library (it may have .lib as extension or .a depending on compiler). You need to link the library to your application which is using your dll. The library contains basically a reduced, short part (stub as the rest of tree when you have cut it down) .

dllimport and dllexport it is called for MS compilers. An inpedendent way is with Q_DECL_IMPORT and Q_DECL_EXPORT

What compiler are you using for creating your application?

[Ahti]

@koahnig

there you go:

https://ibb.co/bDcoXk

[koahnig]

@Ahti

From where did you get the include file HighLevelMonitorConfigurationAPI.h ?

[Ahti]

@koahnig I didn't get it from anywhere i just included it and qt responded on its own by mentioning it in the suggestion list. write this in your qt creator and it will give you a header file with this suggestion:

#include <highlevelmonitorconfigurationapi.h>

[koahnig]

@Ahti

I got it. Never used it.

You are using a MinGW-C++ Gnu-compiler together with a MS library and dll.
I think in general this should be possible as long as the keywords are set properly which I would assume for this header file which is apparently part of MinGW.

Once again, please post the error output as to be found in your output pane. They may hold a clue of the problem.

BTW MS compilers are typically not compatible between its different version and certainly not with MinGW in general.

[Ahti]

@koahnig

Here is the error output: