Qt 5.11 | Qt Core | C++ Classes | const_iterator

Qt 5.11.3 Reference Documentation

# const_iterator Class

(QSequentialIterable::const_iterator)

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

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

- List of all members, including inherited members

## Public Functions

| const_iterator(const const_iterator &other)
| ~const_iterator()
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 QSequentialIterable::const_iterator allows iteration over a container in a QVariant.

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

      QList<int> intList = {7, 11, 42};

      QVariant variant = QVariant::fromValue(intList);
      if (variant.canConvert<QVariantList>()) {
          QSequentialIterable iterable = variant.value<QSequentialIterable>();
          // Can use foreach:
          foreach (const QVariant &v, iterable) {
              qDebug() << v;
          }
          // Can use C++11 range-for:
          for (const QVariant &v : iterable) {
              qDebug() << v;
          }
          // Can use iterators:
          QSequentialIterable::const_iterator it = iterable.begin();
          const QSequentialIterable::const_iterator end = iterable.end();
          for ( ; it != end; ++it) {
              qDebug() << *it;
          }
      }

See also QSequentialIterable.

## Member Function Documentation

### const_iterator::const_iterator(const const_iterator &other)

Creates a copy of other.

### const_iterator::~const_iterator()

Destroys the QSequentialIterable::const_iterator.

### 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 item, 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 QSequentialIterable::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.

If the container in the QVariant does not support bi-directional iteration, calling this function leads to undefined results.

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

### 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 QSequentialIterable::begin() leads to undefined results.

If the container in the QVariant does not support bi-directional iteration, calling this function leads to undefined results.

See also operator++() and canReverseIterate().

### 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.

If the container in the QVariant does not support bi-directional iteration, calling this function leads to undefined results.

See also canReverseIterate().

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

Makes the iterator go back by j items.

If the container in the QVariant does not support bi-directional iteration, calling this function leads to undefined results.

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

### 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!=().