Some questions about using libs in my project

[alexandernst]

I have a few questions about using libraries with my project.

First of all, I have a library project (attached here). I can build it fine, but I don't know how to make my project (my main app) use it.

I have that in my main app pro file:

INCLUDEPATH += ./libs/qtsingleapplication/
LIBS += -L./libs/qtsingleapplication/ -lqtsingleapplication

INCLUDEPATH += ./libs/qtsingleapplication/
LIBS += -L./libs/qtsingleapplication/ -lqtsingleapplication

To copy to clipboard, switch view to plain text mode 

But when I try to do a

#include <QtSingleApplication>

#include <QtSingleApplication>

To copy to clipboard, switch view to plain text mode 

I get an error saying that the file or folder can't be found.
What else should I do.

My second question is how can I make QtCreator build my library and then my main app according to debug or release. Also, should I change something in the pro file of my lib or in the pro file of my app to make them see that they should behave in a different way when debug or release is selected.

Regards!

qtsingleapplication.zip

[tbscope]

#include <QtSingleApplication>

#include <QtSingleApplication>

To copy to clipboard, switch view to plain text mode 

and

INCLUDEPATH += ./libs/qtsingleapplication/

INCLUDEPATH += ./libs/qtsingleapplication/

To copy to clipboard, switch view to plain text mode 

This means it searches for the QtSingleApplication first in the known include paths like /usr/include etc...
If it doesn't find it, it will look in the paths you defined in the pro file, in your case it will look for:

/home/youraccount/yourproject/builddir/libs/qtsingleapplication/QtSingleApplication

/home/youraccount/yourproject/builddir/libs/qtsingleapplication/QtSingleApplication

To copy to clipboard, switch view to plain text mode 

Is this the correct path for the header?

As for building the library in debug or release, you can adjust the project settings. There's a projects button on the left hand side of the Qt Creator window. If you click on that button you'll get a lot of build and run options that you can create or choose from.

[alexandernst]

But my lib has a few source files that depend on the system that it's built (qtsingleapplication_win.cpp, qtsingleapplication_mac.cpp, qtsingleapplication_x11.cpp)
And I have a pri file that makes 'make' compile only the source file that is needed.

On the other hand, if I add the INCLUDEPATH as you said, I get an "undefined reference to "QtSingleApplication::<methods_go_here>" (I guess that this is happening because of what I already said about the source files)

How can I fix that?

[alexandernst]

Ok, I figured out how to use my lib with my project. I made a pro file for building my lib. It looks like this:

TEMPLATE = lib
 
INCLUDEPATH += $$PWD
 
HEADERS += $$PWD/qtglobal.h \
           $$PWD/qtglobalshortcut.h \
           $$PWD/qtglobalshortcut_p.h
 
SOURCES += $$PWD/qtglobal.cpp \
           $$PWD/qtglobalshortcut.cpp
 
macx{
  SOURCES += $$PWD/qtglobalshortcut_mac.cpp
}
 
unix:!mac{
  SOURCES += $$PWD/qtglobalshortcut_x11.cpp
}
 
win32{
  SOURCES += $$PWD/qtglobalshortcut_win.cpp
}

TEMPLATE = lib

INCLUDEPATH += $$PWD

HEADERS += $$PWD/qtglobal.h \
           $$PWD/qtglobalshortcut.h \
           $$PWD/qtglobalshortcut_p.h

SOURCES += $$PWD/qtglobal.cpp \
           $$PWD/qtglobalshortcut.cpp

macx{
  SOURCES += $$PWD/qtglobalshortcut_mac.cpp
}

unix:!mac{
  SOURCES += $$PWD/qtglobalshortcut_x11.cpp
}

win32{
  SOURCES += $$PWD/qtglobalshortcut_win.cpp
}

To copy to clipboard, switch view to plain text mode 

Everything works fine when compiling/running my app, and I'm able to use the functions in my lib. The problem is that when I build everything, my lib goes to the same directory that my main app, while in the "source structure" my library is under myproject/libs/my_library/.

How can I make qtcreator build my library in that same folder structure but in the build directory?