I have a problem with qmake and the make file that it generates. My program needs to be linked against two libraries. I add them in main.pro as follows.
LIBS += -L lib/somelib1/bin -lsomelib1 -L lib/somelib2/bin -lsomelib2
How ever I arrange the above line qmake tells gcc this.
g++ -o programname someobject.o -L lib/somelib1/bin lib/somelib2/bin -lsomelib1 -lsomelib2
The problem is that it should look like this.
g++ -o programname someobject.o -L lib/somelib1/bin -L lib/somelib2/bin -lsomelib1
-lsomelib2
GCC gives the following error.
lib/somelib2/bin: file not recognized: Is a directory
Thanks in advance.
You should not put spaces between the flags and the arguments:
LIBS += -Llib/somelib1/bin -lsomelib1 -Llib/somelib2/bin -lsomelib2
Or
LIBS += -L"lib/somelib1/bin" -lsomelib1 -L"lib/somelib2/bin" -lsomelib2
And why are your static/import libraries in the "bin" directory? There should be .a files in the "lib" directory.
You could try putting the library search paths under the QMAKE_LIBDIR tag. So your qmake file would have:
QMAKE_LIBDIR += lib/somelib1/bin lib/somelib2/bin
LIBS += -lsomelib1 -lsomelib2
Related
I had the problem that my Library libboost_system was not working, then I added this line in my linker, and after that it works:
LIBS += -L/usr/lib/x86_64-linux-gnu -lboost_system
So my qustion is; what does -L mean here?
and why the project won't compile without it?
thanks
I have just installed GLFW on OS X 10.9. The headers were installed to /usr/local/include and the library was installed in /usr/local/lib.
I am wondering what else I would have to do to get my C++ program to include the headers like #include "GLFW/glfw3.h" rather than specifying the whole path like #include "usr/local/include/GLFW/glfw3.h".
Same thing goes for the library because as of now I can't even link the library using -lglfw3. Thanks in advance.
You would pass -I /usr/local/include to the compiler as preprocessor flag, and -L /usr/local/lib to the compiler as linker flag. So to build a single source application small.cc compile it as
g++ -Wall -I /usr/local/include -L /usr/local/lib \
small.cc -o small -lglfw3
If building with make just have
CXXFLAGS += -I/usr/local/include
LDFLAGS += -L/usr/local/lib
in your Makefile
If using shared libraries, add once /usr/local/lib to /etc/ld.so.conf and run ldconfig (at least on Linux).
I am trying to learn Qt, I have file test.cpp that I run via the terminal using the following command:
g++ `pkg-config --cflags --libs libsbml` test.cpp -L /usr/local/lib -lsbml -lstdc++ -lm
How can I suppl the same options to Qt?
Thank you.
You could write the qmake snippet below. In short, you would need to take a look at the following qmake variables:
LIBS
INCLUDEPATH
TEMPLATE
TARGET
HEADERS
SOURCES
CONFIG
PKGCONFIG
test.pro
TEMPLATE = app
TARGET = test
INCLUDEPATH += .
LIBS += -L /usr/local/lib -lsbml -lstdc++ -lm
unix {
CONFIG += link_pkgconfig
PKGCONFIG += libsbml
}
HEADERS += test.h
SOURCES += test.cpp
In .pro file add:
LIBS += -L /usr/local/lib -lsbml -lstdc++ -lm
look at the Makefile to figure out what variables are used. The makefile is in the build folder made by Qt.
I try to build an QT project using qmake. For this I need the boost library.
LIBS += -L/usr/lib/ \
-lboost_system \
-lboost_filesystem
But after running qmake, these libraries are not added to the makefile:
LIBS = $(SUBLIBS) -L/usr/X11R6/lib64 -lQt5MultimediaWidgets
-L/build/buildd/qtmultimedia-opensource-src-5.0.1/lib -L/usr/lib/x86_64-linux-gnu
-L/usr/lib/x86_64-linux-gnu/x86_64-linux-gnu -lQt5OpenGL -lQt5Multimedia -lpulse
-lQt5Widgets -lQt5Network -lQt5Gui -lQt5Core -lGL -lpthread
As expected, the linker prints many error like
/usr/include/boost/system/error_code.hpp:214: error: undefined reference to boost::system::generic_category()
If you want to take a look to the whole .pro file, go to https://raw.github.com/francisengelmann/FabScan100/master/qtTest/qtTest.pro
I am also having a similar problem with opencv. Does anyone know how to solve this issue ?
You need to run qmake again after changing the .pro file. Just removing your build directory is not enough.
Also are you sure your qmake target is linux-g++? Does the INCLUDEPATH work?
I know that the library required can be loaded with
LIBS += -L/path/to/lib
recently I have found something like this
LIBS += -L. -L/usr/lib -lphonon -lcurl -ltag -fopenmp -lsayonara_gstreamer
What does "-L." means ?
Uppercase -L increments the libraries search path, while lowercase -l add a library. Then -L. add the build directory as possible recipe of some of the listed libraries.