It is possible, you already have Qt3 installed in your system and you have recently upgraded to Qt4. In order to be able to compile your applications for Qt4, you will have to upgrade your system enviroment so it recognises the new paths. To do this execute the following commands:
export QTDIR=/usr/lib/qt4export PATH=$QTDIR/bin:$PATHexport LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$QTDIR/lib
To test the environment variables you can execute:
echo $QTDIRThis should output:
/usr/lib/qt4
Now you are ready to build your applications for the newer Qt version.