accessing my own class-instances

hi all,
i have filled a QListWidget with instances of my own class cMassnahme which inherits from QListWidgetItem.
Now i want to find all selected items and put their IDs (those are QStrings, i am not talking about their place within the QListWidget) into a QStringList called filterMassnahmen.
The function QListWidget::selectedItems() returns QListWidgetItems, so if i don't use it differently i won't be able to access my method getID() as this is not a method of QListWidgetItem. Therefore i tried

Code:

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QList<cMassnahme *> items = listMassnahmen->selectedItems ();
for (int i = 0; i < items.size(); ++i) {
    filterMassnahmen << items.at(i)->getID();
}

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which gives me the message:

Code:

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error: conversion from `QList<QListWidgetItem*>' to non-scalar type `QList<cMassnahme*>' requested

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how else could i solve that? even if i tried to reimplement selectedItems() i would have to access QListWidgetItem::selectedItems() in there and still get to the same problem.

You can use a cast:

Code:

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foreach( QListWidgetITem *item, listMassnahmen->selectedItems() ) {
    cMassnahme * nameItem = dynamic_cast< cMassnahme * >( item );
    if( nameItem != 0 ) {
        filterMassnahmen << nameItem->getID();
    }
    else {
       // error: not a cMassnahme?
    }
}

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Thank you, i have meanwhile found a similar solution (wondering that i was able to do something rather similar i went through the code there). Now i do:

Code:

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filterMassnahmen.clear();
    QList<QListWidgetItem *> items = listMassnahmen->selectedItems();
    for (int i = 0; i < items.size(); ++i) {
        cMassnahme* anl = (cMassnahme*) items.at(i);
        filterMassnahmen << anl->getID();
    }

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so seems i can easily convert a single item to cMassnahme but not the complete QList. But i have to acknowledge i still don't understand this typecasting thingy... can you tell me where i can read about it?

Quote:

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Originally Posted by mikro

can you tell me where i can read about it?

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http://www.qtcentre.org/forum/f-c-pr...-books-29.html

My personal favorite is "C++ Primer" by Stanley B. Lippman and Josee Lajoie.
There is also a book available on-line: http://mindview.net/Books/TICPP/ThinkingInCPP2e.html