STL or Qt containers?

c++ qt stl
Julien-L picture Julien-L · Nov 3, 2009 · Viewed 38.5k times · Source

What are the pros and cons of using Qt containers (QMap, QVector, etc.) over their STL equivalent?

I can see one reason to prefer Qt:

  • Qt containers can be passed along to other parts of Qt. For example, they can be used to populate a QVariant and then a QSettings (with some limitation though, only QList and QMap/QHash whose keys are strings are accepted).

Is there any other?

Edit: Assuming the application already relies on Qt.

Answer

Doug T. picture Doug T. · Nov 3, 2009

This is a difficult to answer question. It can really boil down to a philosophical/subjective argument.

That being said...

I recommend the rule "When in Rome... Do as the Romans Do"

Which means if you are in Qt land, code as the Qt'ians do. This is not just for readability/consistency concerns. Consider what happens if you store everything in a stl container then you have to pass all that data over to a Qt function. Do you really want to manage a bunch of code that copies things into/out-of Qt containers. Your code is already heavily dependent on Qt, so its not like you're making it any more "standard" by using stl containers. And whats the point of a container if everytime you want to use it for anything useful, you have to copy it out into the corresponding Qt container?

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