Qt6 topics merged with General

Is it hard to move project from Qt3 to Qt5?

  • Hello guys,

    I have one general question. There is one middle size project developed in Qt 3.3.4. I'd like to convert it from Qt3 to Qt5. What do you think, is it going to be hard to move it to Qt5?

    A couple of days managed to move one big project from Qt4 to Qt5. Took me about 2 days. I never worked with Qt3 before, so that's why I'm asking.


  • Hi, whether it is easy or not depending on the classes or apis you used in your project.

    For a general project, it should be rather easy moving Qt4 to Qt5, but it is rather hard moving Qt3 to Qt4.

    If you never worked with Qt3, you must yourself familiar with it.

  • Lifetime Qt Champion


    You can find a good deal of information in Qt 4's porting guide to help you going.

    The savage way would be to try to build your project and see where it chokes then go through the porting to see what you need to replace.

    If you take the two step way (first to Qt 4 then Qt 5) don't use the qt3support module. You'll have to port the code anyway to Qt 5.

    Hope it helps

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