QList removing via iterator problem

fluca1978

Hi all,
I've got a QList of objects named "Role", and I want to remove some of them while iterating the list. The first piece of code I wrote was:

@
QList<Role>::iterator roleIterator;
for( roleIterator = roles.begin(); roleIterator != roles.end(); roleIterator++ ){
const Role& currentRole = *roleIterator;

if( ! currentRole.rootLevelRole() ){
    roleIterator = roles.erase( roleIterator );
}

}
@

but it was not working, that is it what not removing all the items. I noted that it was skipping the next-to-last-erased item, so I changed the code into

@
QList<Role>::iterator roleIterator;
for( roleIterator = roles.begin(); roleIterator != roles.end(); roleIterator++ ){
const Role& currentRole = *roleIterator;

if( ! currentRole.rootLevelRole() ){
  roles.removeOne( currentRole );
}

}
@

that worked. Now I'm confused about the usage of "erase":http://qt-project.org/doc/qt-4.8/qlist.html#erase : am I not supposed to re-assign the iterator once it has been erased?

KA51O

Have a look at "this thread":https://qt-project.org/forums/viewthread/13816/.

task_struct

Also you can read "this article":https://qt-project.org/wiki/QtIterators

fluca1978

Sorry, not sure to get it right, but the problem is the roleIterator++ which increments the iterator that has already advanced by the erase method call. Is it right? Therefore this works:

@
QList<Role>::iterator roleIterator = roles.begin();
while( roleIterator != roles.end() ){
const Role& currentRole = *roleIterator;

    if( ! currentRole.rootLevelRole() ){
        roleIterator = roles.erase( roleIterator );
    }
     else
        roleIterator++;
  }

@

Am I right?

KA51O

Correct.

Aksh

Hii friends...

I am facing problem while deleting item from QList.
is it any difference while deleting item from QList of pointer type elements and deleting item from QList of elements(non pointer)????

QList<Myclass*> MyList; ////////////this is list having 3 items

//trying to delete item having name "abc"

KA51O

the difference is that in order to avoid memory leaks you need to delete pointers and only need to remove the objects allocated on the stack.

Jeroentjehome

If I'm not mistaken, the QList takes ownership of the inserted objects, so when deleting a "pointer" from the list, it will automatic delete the allocated data (if no other references are present).
Greetz