which container (Qvector or QList) is good to use for insert, delete, and access the last element.

Yash001

I am adding data point at last position of container, and only accessing the last element of container. So which is better container?

I am curious to know what is time complexity of QList::last(), O(n) or O(1)?
If I am not wrong then doubly link list: O(1) and singly link list has O(n).

guerinoni

@Yash001 QVector is better, in Qt6 QList is merged into QVector

fcarney

QLinkedList?

JonB

@Yash001 said in which container (Qvector or QList) is good to use for insert, delete, and access the last element.:

I am curious to know what is time complexity of QList::last(), O(n) or O(1)?

I think you'll find it's O(1). By inspection of https://code.woboq.org/qt5/qtbase/src/corelib/tools/qlist.h.html. For example

    inline void **end() const noexcept { return d->array + d->end; }
    T& last() { Q_ASSERT(!isEmpty()); return *(--end()); }

QVector will surely be O(1), and if @guerinoni suggests that's the way to go for the future he probably knows what he is talking about :)

mpergand

@Yash001 said in which container (Qvector or QList) is good to use for insert, delete, and access the last element.:

I am adding data point at last position of container, and only accessing the last element of container. So which is better container?

It's what we call Last In First Out ( LIFO) queue.
So QStack seems an obvious candidate.

QStack inherits from QVector.