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/Qt 5.11

const_iterator Class

(QAssociativeIterable::const_iterator)

The QAssociativeIterable::const_iterator allows iteration over a container in a QVariant. More...

Header: #include <const_iterator>
qmake: QT += core
Since: Qt 5.2

Public Functions

const_iterator(const const_iterator &other)
~const_iterator()
const QVariant key() const
const QVariant value() const
bool operator!=(const const_iterator &other) const
const QVariant operator*() const
const_iterator operator+(int j) const
const_iterator & operator++()
const_iterator operator++(int)
const_iterator & operator+=(int j)
const_iterator operator-(int j) const
const_iterator & operator--()
const_iterator operator--(int)
const_iterator & operator-=(int j)
const_iterator & operator=(const const_iterator &other)
bool operator==(const const_iterator &other) const

Detailed Description

The QAssociativeIterable::const_iterator allows iteration over a container in a QVariant.

A QAssociativeIterable::const_iterator can only be created by a QAssociativeIterable instance, and can be used in a way similar to other stl-style iterators.

QHash<int, QString> mapping;
mapping.insert(7, "Seven");
mapping.insert(11, "Eleven");
mapping.insert(42, "Forty-two");

QVariant variant = QVariant::fromValue(mapping);
if (variant.canConvert<QVariantHash>()) {
    QAssociativeIterable iterable = variant.value<QAssociativeIterable>();
    // Can use foreach over the values:
    foreach (const QVariant &v, iterable) {
        qDebug() << v;
    }
    // Can use C++11 range-for over the values:
    for (const QVariant &v : iterable) {
        qDebug() << v;
    }
    // Can use iterators:
    QAssociativeIterable::const_iterator it = iterable.begin();
    const QAssociativeIterable::const_iterator end = iterable.end();
    for ( ; it != end; ++it) {
        qDebug() << *it; // The current value
        qDebug() << it.key();
        qDebug() << it.value();
    }
}

See also QAssociativeIterable.

Member Function Documentation

const_iterator::const_iterator(const const_iterator &other)

Creates a copy of other.

const_iterator::~const_iterator()

Destroys the QAssociativeIterable::const_iterator.

const QVariant const_iterator::key() const

Returns the current key, converted to a QVariant.

const QVariant const_iterator::value() const

Returns the current value, converted to a QVariant.

bool const_iterator::operator!=(const const_iterator &other) const

Returns true if other points to a different item than this iterator; otherwise returns false.

See also operator==().

const QVariant const_iterator::operator*() const

Returns the current value, converted to a QVariant.

const_iterator const_iterator::operator+(int j) const

Returns an iterator to the item at j positions forward from this iterator.

See also operator-() and operator+=().

const_iterator &const_iterator::operator++()

The prefix ++ operator (++it) advances the iterator to the next item in the container and returns an iterator to the new current item.

Calling this function on QAssociativeIterable::end() leads to undefined results.

See also operator--().

const_iterator const_iterator::operator++(int)

This is an overloaded function.

The postfix ++ operator (it++) advances the iterator to the next item in the container and returns an iterator to the previously current item.

const_iterator &const_iterator::operator+=(int j)

Advances the iterator by j items.

See also operator-=() and operator+().

const_iterator const_iterator::operator-(int j) const

Returns an iterator to the item at j positions backward from this iterator.

See also operator+() and operator-=().

const_iterator &const_iterator::operator--()

The prefix -- operator (--it) makes the preceding item current and returns an iterator to the new current item.

Calling this function on QAssociativeIterable::begin() leads to undefined results.

See also operator++().

const_iterator const_iterator::operator--(int)

This is an overloaded function.

The postfix -- operator (it--) makes the preceding item current and returns an iterator to the previously current item.

const_iterator &const_iterator::operator-=(int j)

Makes the iterator go back by j items.

See also operator+=() and operator-().

const_iterator &const_iterator::operator=(const const_iterator &other)

Assigns other to this.

bool const_iterator::operator==(const const_iterator &other) const

Returns true if other points to the same item as this iterator; otherwise returns false.

See also operator!=().

© The Qt Company Ltd
Licensed under the GNU Free Documentation License, Version 1.3.
https://doc.qt.io/qt-5/qassociativeiterable-const-iterator.html