qt 4.5 vs qt 3.8 (textbook says qt 4.3)
 

Alright dig this, what if I have slack 12.2 and I remove the qt 3.8 (or 3.8.8 or whatever it was) with pkgtool and then I install qt 4.5 or something with a slackbuild. If I do that then the command "qmake" now does nothing.

I have to create a file called ".profile" in my home directory and put
PATH=/tmp/SBo/qt-x11-opensource-src-4.5.1/bin:$PATH
export PATH

in that file, then log out and log back in. Now "qmake" works. So slackbuilds don't do that stuff automatically for me? Or was I supposed to do something with ldconfig or something?

Okay now suppose I have a book that teaches QT but it says to use QT 4.3.2 or better. Can I put qt 3.8 back on my system to get konsole and konqueror and all that stuff running again and still use qt 4.5 to compile my own stuff? Or is it possible for my KDE 3 apps to use qt 4.5 instead? (I doubt that.) Can KDevelop 3.5 compile and do stuff with qt 4.5? Or should I just give up and install slackware 13 and use the beta version of kdevelop 4? (I'm not sure I want to use a beta kdevelop.)

Did you read the readme that accompanies the qt4 SlackBuild? The package is built to coexist with QT3. You should leave the QT3 stuff alone on your system (ie reinstall it if you have uninstalled it at some point) and then compile QT4 with the SlackBuild. It looks like you missed a step -- actually installing the package. Follow these instructions to use SlackBuilds properly. It should have created a package in /tmp/ (or whatever you set the OUTPUT variable to) that you can install with

I recommend using Qt Creator as your IDE.

Since you are running 12.2 which came natively with QT 3.x, you have a few choices in which will allow you to maintain a working system.

Correctly follow the instruction from the SlackBuild which was written for QT 4 and Slackware 12.2 ( http://slackbuilds.org/repository/12.2/libraries/qt4/ )

Correctly follow the instructions, and upgrade to KDE 4 and QT 4 from testing, you'll have to write info at slackware.com and express interest in obtaining this disc. Or perhaps some knows of a mirror that keeps previous testing/ directories populated.

Looks like T3slider got in before I did :)

That's what I did until the end. I just installed the package with pkgtool instead of the installpkg command. You think that's why I had to add the /bin directory to PATH manually? I guess I will test that right now.

But yeah they seem to be working side by side. I didn't even have to do "qmake-qt4" like it says I'm supposed to, it automatically used the correct qmake. (maybe because the qt4 variable is in my PATH before the qt 3 variable? but konsole and everything still find qt3 just fine.) Beats me.

Oh wait... I wonder if they were working correctly side by side since the beginning but I was typing "qmake" instead of "qmake-qt4" like I was supposed to so it was using the qt3 for the qt4 examples I typed up from my textbook and it wouldn't work. And then when I added /tmp/SBo/qt-x11-opensource-src-4.5.1/bin to my PATH variable manually then the command "qmake" found qt4 first just because it was my first string in PATH? Hold on I gotta read the readme's again and start over. It's possible I never had any problems to begin with and I just made them up.

lol, that was it. I actually had them both installed correctly on my first try. I just kept typing "qmake -project", "qmake xxx.pro", "make" instead of "qmake-qt4 -project", "qmake-qt4 xxx.pro", "make" like I was supposed to so it was using qt3.