Can not create/use DLL

SGaist

In the qmake manual

JacobNovitsky

Libtest.pro
QT = core

CONFIG += c++17 cmdline

You can make your code fail to compile if it uses deprecated APIs.

In order to do so, uncomment the following line.

#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0

SOURCES +=
main.cpp

Default rules for deployment.

qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

LIBS +=/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
INCLUDEPATH +=/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
DEPENDPATH +=/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
PRE_TARGETDEPS +=/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug

MyLib.pro

QT -= gui

TEMPLATE = lib
DEFINES += MYLIB_LIBRARY

CONFIG += c++17

You can make your code fail to compile if it uses deprecated APIs.

In order to do so, uncomment the following line.

#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0

SOURCES +=
mylib.cpp

HEADERS +=
MyLib_global.h
mylib.h

Default rules for deployment.

unix {
target.path = /usr/lib
}
!isEmpty(target.path): INSTALLS += target

:-1: error: cannot find /home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug: file format not recognized

How to fix error above? There is still no DLL, if I comply with syntax, shall I get dll?

jsulm

@JacobNovitsky You should really read the link @SGaist gave you.
In LIBS you need to also specify the lib you want to link.

JacobNovitsky

@jsulm if I use in the LIBS line something with prefix -lmylib it does not work :)
what should I exactly insert to LIBS line?

JacobNovitsky

changed to

    LIBS += -L/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug -lMyLib
    INCLUDEPATH += /home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
    DEPENDPATH += /home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
    PRE_TARGETDEPS += /home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug

it builds, but how to gett .dll file?

JacobNovitsky

If I just link header which includes other project headers, it means my program auto include all headers which increase building and execution time?
same going to happen if I use dll, I'm I correct?

SGaist

@JacobNovitsky said in Can not create/use DLL:

changed to

    LIBS += -L/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug -lMyLib
    INCLUDEPATH += /home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
    DEPENDPATH += /home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
    PRE_TARGETDEPS += /home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug

it builds, but how to gett .dll file?

If after building, you don't have any dll then it means you are not exporting anything from your code.

SGaist

@JacobNovitsky said in Can not create/use DLL:

If I just link header which includes other project headers, it means my program auto include all headers which increase building and execution time?
same going to happen if I use dll, I'm I correct?

Build time, yes hence only include what you use in your headers and for the rest use forward declarations. As for execution time, no, it's not directly related.

What do you mean by "if I use dll".

JacobNovitsky

@SGaist It feels like I'm close to solve this, what am I missing? What I need to do in order to get dll?

SGaist

@JacobNovitsky as I wrote: check that you are properly exporting stuff from your library code.