so I am wanting to interface the mosquitto mqtt library into qt creator (c ), to create a graphical program for using mqtt. I am trying to figure out how to add the -lmosquitto compiler option, I have seen similar posts about adding c compiler options by using line shown below inside the .pro file

QMAKE_CXXFLAGS  = compiler option here 

I tried to add the -lmosquitto compiler option in the same way shown below

QMAKE_CXXFLAGS  = -lmosquitto

but I still get errors saying undefined reference to 'function names'

Does anyone know how to add compiler options for libraries into qt

FYI: I am using ubuntu, in qt creator I am creating widget application, and I am sure the -lmosquitto is the correct option as I can compile code wrote in text editor from command line using it.

Any help with this would be great,

Thanks in advance, Dean

CodePudding user response：

As a general advice I would give you is, to use CMake with QT. QT supports CMake since QT5 IIRC, and since QT6 it is the standard build tool if I'm not mistaken. The benefit of using CMake is that you will find more answers to your questions.

That being said, if you still wish to use qmake instead of CMake then last I checked, you will need to add a line like this to your .pro file:

LIBS  = -L/path/to/your/mosquitto_library -lmosquitto 

Notice the -L flag where you specify the library path. This is essentially what is missing from your CXX flags.