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/Qt 5.11

const_iterator Class

(QFuture::const_iterator)

The QFuture::const_iterator class provides an STL-style const iterator for QFuture. More...

Header: #include <const_iterator>
qmake: QT += core
Since: Qt 4.4

Note: All functions in this class are reentrant.

Public Types

typedef difference_type
typedef iterator_category
typedef pointer
typedef reference
typedef value_type

Public Functions

const_iterator()
const_iterator(const const_iterator &other)
bool operator!=(const const_iterator &other) const
const T & 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 T * operator->() const
const_iterator & operator=(const const_iterator &other)
bool operator==(const const_iterator &other) const

Detailed Description

The QFuture::const_iterator class provides an STL-style const iterator for QFuture.

QFuture provides both STL-style iterators and Java-style iterators. The STL-style iterators are more low-level and more cumbersome to use; on the other hand, they are slightly faster and, for developers who already know STL, have the advantage of familiarity.

The default QFuture::const_iterator constructor creates an uninitialized iterator. You must initialize it using a QFuture function like QFuture::constBegin() or QFuture::constEnd() before you start iterating. Here's a typical loop that prints all the results available in a future:

QFuture<QString> future = ...;

QFuture<QString>::const_iterator i;
for (i = future.constBegin(); i != future.constEnd(); ++i)
    cout << *i << endl;

See also QFutureIterator and QFuture.

Member Type Documentation

typedef const_iterator::difference_type

Typedef for ptrdiff_t. Provided for STL compatibility.

typedef const_iterator::iterator_category

Typedef for std::bidirectional_iterator_tag. Provided for STL compatibility.

typedef const_iterator::pointer

Typedef for const T *. Provided for STL compatibility.

typedef const_iterator::reference

Typedef for const T &. Provided for STL compatibility.

typedef const_iterator::value_type

Typedef for T. Provided for STL compatibility.

Member Function Documentation

const_iterator::const_iterator()

Constructs an uninitialized iterator.

Functions like operator*() and operator++() should not be called on an uninitialized iterartor. Use operator=() to assign a value to it before using it.

See also QFuture::constBegin() and QFuture::constEnd().

const_iterator::const_iterator(const const_iterator &other)

Constructs a copy of other.

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

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

See also operator==().

const T &const_iterator::operator*() const

Returns the current result.

const_iterator const_iterator::operator+(int j) const

Returns an iterator to the results at j positions forward from this iterator. (If j is negative, the iterator goes backward.)

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

const_iterator &const_iterator::operator++()

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

Calling this function on QFuture<T>::constEnd() 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 result in the future and returns an iterator to the previously current result.

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

Advances the iterator by j results. (If j is negative, the iterator goes backward.)

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

const_iterator const_iterator::operator-(int j) const

Returns an iterator to the result at j positions backward from this iterator. (If j is negative, the iterator goes forward.)

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

const_iterator &const_iterator::operator--()

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

Calling this function on QFuture<T>::constBegin() 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 result current and returns an iterator to the previously current result.

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

Makes the iterator go back by j results. (If j is negative, the iterator goes forward.)

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

const T *const_iterator::operator->() const

Returns a pointer to the current result.

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

Assigns other to this iterator.

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

Returns true if other points to the same result 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/qfuture-const-iterator.html