Viadeo Twitter Google Bookmarks ! Facebook Digg del.icio.us MySpace Yahoo MyWeb Blinklist Netvouz Reddit Simpy StumbleUpon Bookmarks Windows Live Favorites 
Logo Documentation Qt ·  Page d'accueil  ·  Toutes les classes  ·  Classes principales  ·  Annotées  ·  Classes groupées  ·  Modules  ·  Fonctions  · 

QMutableLinkedListIterator Class Reference
[QtCore module]

The QMutableLinkedListIterator class provides a Java-style non-const iterator for QLinkedList. More...

#include <QMutableLinkedListIterator>

Public Functions


Detailed Description

The QMutableLinkedListIterator class provides a Java-style non-const iterator for QLinkedList.

QLinkedList has both Java-style iterators and STL-style iterators. The Java-style iterators are more high-level and easier to use than the STL-style iterators; on the other hand, they are slightly less efficient.

QMutableLinkedListIterator<T> allows you to iterate over a QLinkedList<T> and modify the list. If you don't want to modify the list (or have a const QLinkedList), use the slightly faster QLinkedListIterator<T> instead.

The QMutableLinkedListIterator constructor takes a QLinkedList as argument. After construction, the iterator is located at the very beginning of the list (before the first item). Here's how to iterate over all the elements sequentially:

    QLinkedList<float> list;
    ...
    QMutableLinkedListIterator<float> i(list);
    while (i.hasNext())
        qDebug() << i.next();

The next() function returns the next item in the list and advances the iterator. Unlike STL-style iterators, Java-style iterators point between items rather than directly at items. The first call to next() advances the iterator to the position between the first and second item, and returns the first item; the second call to next() advances the iterator to the position between the second and third item, returning the second item; and so on.

Here's how to iterate over the elements in reverse order:

    QMutableLinkedListIterator<float> i(list);
    i.toBack();
    while (i.hasPrevious())
        qDebug() << i.previous();

If you want to find all occurrences of a particular value, use findNext() or findPrevious() in a loop.

If you want to remove items as you iterate over the list, use remove(). If you want to modify the value of an item, use setValue(). If you want to insert a new item in the list, use insert().

Example:

    QMutableLinkedListIterator<int> i(list);
    while (i.hasNext()) {
        int val = i.next();
        if (val < 0) {
            i.setValue(-val);
        } else if (val == 0) {
            i.remove();
        }
    }

The example traverses a list, replacing negative numbers with their absolute values, and eliminating zeroes.

Only one mutable iterator can be active on a given list at any time. Furthermore, no changes should be done directly to the list while the iterator is active (as opposed to through the iterator), since this could invalidate the iterator and lead to undefined behavior.

See also QLinkedListIterator and QLinkedList::iterator.


Member Function Documentation

QMutableLinkedListIterator::QMutableLinkedListIterator ( QLinkedList<T> & list )

Constructs an iterator for traversing list. The iterator is set to be at the front of the list (before the first item).

See also operator=().

QMutableLinkedListIterator::~QMutableLinkedListIterator ()

Destroys the iterator.

See also operator=().

bool QMutableLinkedListIterator::findNext ( const T & value )

Searches for value starting from the current iterator position forward. Returns true if value is found; otherwise returns false.

After the call, if value was found, the iterator is positioned just after the matching item; otherwise, the iterator is positioned at the back of the container.

See also findPrevious().

bool QMutableLinkedListIterator::findPrevious ( const T & value )

Searches for value starting from the current iterator position backward. Returns true if value is found; otherwise returns false.

After the call, if value was found, the iterator is positioned just before the matching item; otherwise, the iterator is positioned at the front of the container.

See also findNext().

bool QMutableLinkedListIterator::hasNext () const

Returns true if there is at least one item ahead of the iterator, i.e. the iterator is not at the back of the container; otherwise returns false.

See also hasPrevious() and next().

bool QMutableLinkedListIterator::hasPrevious () const

Returns true if there is at least one item behind the iterator, i.e. the iterator is not at the front of the container; otherwise returns false.

See also hasNext() and previous().

void QMutableLinkedListIterator::insert ( const T & value )

Inserts value at the current iterator position. After the call, the iterator is located just after the inserted item.

See also remove() and setValue().

T & QMutableLinkedListIterator::next ()

Returns a reference to the next item, and advances the iterator by one position.

Calling this function on an iterator located at the back of the container leads to undefined results.

See also hasNext(), peekNext(), and previous().

T & QMutableLinkedListIterator::peekNext () const

Returns a reference to the next item, without moving the iterator.

Calling this function on an iterator located at the back of the container leads to undefined results.

See also hasNext(), next(), and peekPrevious().

T & QMutableLinkedListIterator::peekPrevious () const

Returns a reference to the previous item, without moving the iterator.

Calling this function on an iterator located at the front of the container leads to undefined results.

See also hasPrevious(), previous(), and peekNext().

T & QMutableLinkedListIterator::previous ()

Returns a reference to the previous item and moves the iterator back by one position.

Calling this function on an iterator located at the front of the container leads to undefined results.

See also hasPrevious(), peekPrevious(), and next().

void QMutableLinkedListIterator::remove ()

Removes the last item that was jumped over using one of the traversal functions (next(), previous(), findNext(), findPrevious()).

Example:

    QMutableLinkedListIterator<int> i(list);
    while (i.hasNext()) {
        int val = i.next();
        if (val < -32768 || val > 32767)
            i.remove();
    }

See also insert() and setValue().

void QMutableLinkedListIterator::setValue ( const T & value ) const

Replaces the value of the last item that was jumped over using one of the traversal functions with value.

The traversal functions are next(), previous(), findNext(), and findPrevious().

Example:

    QMutableLinkedListIterator<double> i(list);
    while (i.hasNext()) {
        double val = i.next();
        i.setValue(sqrt(val));
    }

See also value(), remove(), and insert().

void QMutableLinkedListIterator::toBack ()

Moves the iterator to the back of the container (after the last item).

See also toFront() and previous().

void QMutableLinkedListIterator::toFront ()

Moves the iterator to the front of the container (before the first item).

See also toBack() and next().

const T & QMutableLinkedListIterator::value () const

Returns the value of the last item that was jumped over using one of the traversal functions (next(), previous(), findNext(), findPrevious()).

After a call to next() or findNext(), value() is equivalent to peekPrevious(). After a call to previous() or findPrevious(), value() is equivalent to peekNext().

See also setValue().

T & QMutableLinkedListIterator::value ()

This is an overloaded member function, provided for convenience.

Returns a non-const reference to the value of the last item that was jumped over using one of the traversal functions.

QMutableLinkedListIterator & QMutableLinkedListIterator::operator= ( QLinkedList<T> & list )

Makes the iterator operate on list. The iterator is set to be at the front of the list (before the first item).

See also toFront() and toBack().

Publicité

Best Of

Actualités les plus lues

Semaine
Mois
Année
  1. « Quelque chose ne va vraiment pas avec les développeurs "modernes" », un développeur à "l'ancienne" critique la multiplication des bibliothèques 94
  2. Apercevoir la troisième dimension ou l'utilisation multithreadée d'OpenGL dans Qt, un article des Qt Quarterly traduit par Guillaume Belz 0
  3. Pourquoi les programmeurs sont-ils moins payés que les gestionnaires de programmes ? Manquent-ils de pouvoir de négociation ? 48
  4. Les développeurs ignorent-ils trop les failles découvertes dans leur code ? Prenez-vous en compte les remarques des autres ? 17
  5. Les développeurs détestent-ils les antivirus ? Un programmeur manifeste sa haine envers ces solutions de sécurité 13
  6. Quelles nouveautés de C++11 Visual C++ doit-il rapidement intégrer ? Donnez-nous votre avis 10
  7. Qt Commercial : Digia organise un webinar gratuit le 27 mars sur la conception d'interfaces utilisateur et d'applications avec le framework 0
Page suivante

Le Qt Developer Network au hasard

Logo

Compiler l'add-in Qt de Visual Studio

Le Qt Developer Network est un réseau de développeurs Qt anglophone, où ils peuvent partager leur expérience sur le framework. Lire l'article.

Communauté

Ressources

Liens utiles

Contact

  • Vous souhaitez rejoindre la rédaction ou proposer un tutoriel, une traduction, une question... ? Postez dans le forum Contribuez ou contactez-nous par MP ou par email (voir en bas de page).

Qt dans le magazine

Cette page est une traduction d'une page de la documentation de Qt, écrite par Nokia Corporation and/or its subsidiary(-ies). Les éventuels problèmes résultant d'une mauvaise traduction ne sont pas imputables à Nokia. Qt 4.1
Copyright © 2012 Developpez LLC. Tous droits réservés Developpez LLC. Aucune reproduction, même partielle, ne peut être faite de ce site et de l'ensemble de son contenu : textes, documents et images sans l'autorisation expresse de Developpez LLC. Sinon, vous encourez selon la loi jusqu'à 3 ans de prison et jusqu'à 300 000 E de dommages et intérêts. Cette page est déposée à la SACD.
Vous avez déniché une erreur ? Un bug ? Une redirection cassée ? Ou tout autre problème, quel qu'il soit ? Ou bien vous désirez participer à ce projet de traduction ? N'hésitez pas à nous contacter ou par MP !
 
 
 
 
Partenaires

Hébergement Web