I would like to build a graphic user interface for an application written in C++ and running on a AMD Turion64 using linux mandriva 64 or fedora 4 64. I will really appreciate if you can tell me the step to follow. It seems that linux 64 is very poor in library in comparison with linux 32.

Thank you for your help

There is more than one way to do it.
Which language are you planning to use to write the GUI? You can use C++ (same as the application itself), or another, like perl, python and what have you.
You need a GUI library like tk or better gtk2 or Qt (Qt is not free though). The libraries can be compiled in 64 bit, although I doubt the GUI will gain anything from 64 bit.

Qt *is* free - it's released under the GPL.

You only have to pay for it if you want to keep your code proprietary.

Thank you for your answer.

I am planning on using C++ to write the interface. The GUI is too show dynamic data in real time. I do not know if gtk2 can do that and can be used on a linux 64 platform.

Sorry, my bad.
Qt is indeed free.

Get gtk2 x86_64 dev rpm from some rpm finder on the internet or compile it yourself.
gtk2 looks like gnome (but can be used anywhere else) and Qt looks like KDE.
Both are free and both can display real time dynamic data with no problem. Both can be compiled or found pre-compiled in 64 bit rpms.

Of course GTK and Qt can be used on a 64bit platform, if you are using a GUI on either Mandriva or Fedora 64 then chances are you will be using GTK and Qt apps unless you stripped down the install majorly.

Please don't post incorrect information as you could mislead people who are researching linux on 64bit and considering a swap.

There is wxWidgets. Audacity and Video Lan Client uses wxWidgets. I suggest using a distribution that uses gcc version 3.2 through 3.5. Fedora 4 uses gcc version 4 which has problems compiling programs. Gentoo and Slackware are good distributions to write programs.

I agree, GUI does not get any benefits when compiled for 64-bit. Multimedia programs like ffmpeg, mplayer, xine-lib, and transcode gets increase performance with 64-bit instructions.

For a real-time application it is better to create a backend than creating GUI program to do operations in real-time. GUI is not real-time.