# How to link libraries like qxt or qwt?

• Hi folks,

I'm wondering how do Qxt and Qwt build their libraries so we can include later on like this
@CONFIG += qxt
QXT = core gui@

I'm looking at the sources but I'm getting lost! Thanks.

Edit: I'm diving into it and found about .prf files and the QtDir/mkspecs/features folder. What should I do when compiling my lib to place the .prf file so a user compiling my lib can use it in CONFIG?

• Hi,

the prf files is the secret you are searching. Look in e.g. /usr/local/qwt-6.1.0-svn/features

• Hi SGaist, thanks for the reply (funny, I've edited my answer just before you post).

I'll dive more now I know about prf files. Thanks.

• You're welcome !

You can find some information in qmake's documentation under "qmake Advance Usage" chapter "Adding New Configuration Features"

• I've finally got it working, but I think I've found a bug:
when I compile using Qt Creator, the make instruction doesn't include the headers and libs I've declared in my prf file.

When I do inside the terminal (qmake & make) I can see the include headers and libs, and effectively builds fine.

Should I report a bug?

• Did you update an environment variable on the console ? If so, the environment in QtCreator might be outdated so it doesn't reflect what you did

• The problem is that the qmake I was using through terminal belongs to another Qt version. I didn't even know I had Qt5.0.2 along with Qt5.1.1, funny!

• Naughty phantom Qt install... :-D