Look in while statement....
9/14/2015 6:28 PM, Croitor Alexandru пишет:
The documentation for QList::erase says:
-- Removes the item associated with the iterator /pos/ from the list,
and returns an iterator to the next item in the list (which may be end
<file:///Users/placinta/Library/Application%20Support/Dash/DocSets/Qt_5/Qt.docset/Contents/Resources/Documents/doc.qt.io/qt-5/qlist.html#end>()).
Documentation for iterator::operator++() says:
Calling this function on QList::end
<file:///Users/placinta/Library/Application%20Support/Dash/DocSets/Qt_5/Qt.docset/Contents/Resources/Documents/doc.qt.io/qt-5/qlist.html#end>()
leads to undefined results.
You have no check in your code to see if the iterator return by erase
is QList::end(), thus calling operator++ on it might crash your
application.
On Mon, Sep 14, 2015 at 6:13 PM, Igor Mironchik
<igor.mironc...@gmail.com <mailto:igor.mironc...@gmail.com>> wrote:
Hi,
it seems that problem not in the iterating and deletion from
cantainer...
I wrote simple test app and everything is ok.
But something here crashes my app and only in release mode, so I can't
understand what is the problem...
And ideas?
9/14/2015 6:06 PM, André Somers пишет:
> Op 14-9-2015 om 16:57 schreef Igor Mironchik:
>> Hi,
>>
>> I ran into this problem...
>>
>> void
>> ImageFilesStoragePrivate::removeAllImages(
>> QList< ImageRecord > & images,
>> ImageFilesStorage::ImageType type )
>> {
>> QList< ImageRecord >::Iterator it = images.begin();
>> QList< ImageRecord >::Iterator last = images.end();
>>
>> while( it != last )
>> {
>> if( (*it).m_type == type )
>> {
>> LOG( DebugLogLevel, "Before real deletion" )
>> removeFromDatabase( it );
>> LOG( DebugLogLevel, "After real deletion" )
>>
>> // it = images.erase( it ); // LOOK AT THIS LINE !!!
If I
>> uncomment it and comment next line - crash...
>> ++it;
>>
>> LOG( DebugLogLevel, QString( "it == last : %1"
).arg( ( it
>> == last ? "true" : "false" ) ) )
>> }
>> else
>> ++it;
>> }
>> }
>>
>> What is wrong?
> A lot is wrong.
>
> First, you are not using standard algorithms to do standard
things. I'd
> say std::remove_if with std::erase would be a better way to
solve the issue.
>
> Then in general, if you delete from the container, iterators are
going
> to be invalidated. Iterate backwards if you are going to delete
items
> from the container.
>
> Last: you probably don't want to use QList but QVector.
>
> André
>
>
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