const_iterator Class

class QJsonObject::const_iterator

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

This class was introduced in Qt 5.0.

• List of all members, including inherited members

Public Types

iterator_category

Public Functions

	const_iterator(const iterator &other)
	const_iterator()
QString	key() const
QJsonValueRef	value() const
bool	operator!=(const const_iterator &other) const
bool	operator!=(const iterator &other) const
const QJsonValueRef	operator*() const
const_iterator	operator+(qsizetype j) const
const_iterator &	operator++()
const_iterator	operator++(int)
const_iterator &	operator+=(qsizetype j)
const_iterator	operator-(qsizetype j) const
qsizetype	operator-(const_iterator other) const
const_iterator &	operator--()
const_iterator	operator--(int)
const_iterator &	operator-=(qsizetype j)
const QJsonValueRef *	operator->() const
bool	operator<(const const_iterator &other) const
bool	operator<=(const const_iterator &other) const
bool	operator==(const const_iterator &other) const
bool	operator==(const iterator &other) const
bool	operator>(const const_iterator &other) const
bool	operator>=(const const_iterator &other) const
const QJsonValueRef	operator[](qsizetype j)

Detailed Description

QJsonObject::const_iterator allows you to iterate over a QJsonObject. If you want to modify the QJsonObject as you iterate over it, you must use QJsonObject::iterator instead. It is generally good practice to use QJsonObject::const_iterator on a non-const QJsonObject as well, unless you need to change the QJsonObject through the iterator. Const iterators are slightly faster and improve code readability.

The default QJsonObject::const_iterator constructor creates an uninitialized iterator. You must initialize it using a QJsonObject function like QJsonObject::constBegin(), QJsonObject::constEnd(), or QJsonObject::find() before you can start iterating.

Multiple iterators can be used on the same object. Existing iterators will however become dangling if the object gets modified.

See also QJsonObject::iterator, JSON Support in Qt, and JSON Save Game Example.

Member Type Documentation

const_iterator::iterator_category

A synonym for std::random_access_iterator_tag indicating this iterator is a random-access iterator.

Note: In Qt versions before 5.6, this was set by mistake to std::bidirectional_iterator_tag.

Member Function Documentation

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

See also operator==().

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

See also operator!=().

const_iterator::const_iterator(const iterator &other)

Constructs a copy of other.

const_iterator::const_iterator()

Constructs an uninitialized iterator.

Functions like key(), value(), and operator++() must not be called on an uninitialized iterator. Use operator=() to assign a value to it before using it.

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

QString const_iterator::key() const

Returns the current item's key.

See also value().

QJsonValueRef const_iterator::value() const

Returns the current item's value.

See also key() and operator*().

const QJsonValueRef const_iterator::operator*() const

Returns the current item's value.

Same as value().

See also key().

const_iterator const_iterator::operator+(qsizetype j) const

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

This operation can be slow for large j values.

See also operator-().

const_iterator &const_iterator::operator++()

The prefix ++ operator, ++i, advances the iterator to the next item in the object and returns an iterator to the new current item.

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

See also operator--().

const_iterator const_iterator::operator++(int)

This is an overloaded function.

The postfix ++ operator, i++, advances the iterator to the next item in the object and returns an iterator to the previously current item.

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

Advances the iterator by j items. If j is negative, the iterator goes backward.

This operation can be slow for large j values.

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

const_iterator const_iterator::operator-(qsizetype j) const

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

This operation can be slow for large j values.

See also operator+().

qsizetype const_iterator::operator-(const_iterator other) const

Returns the number of items between the item pointed to by other and the item pointed to by this iterator.

const_iterator &const_iterator::operator--()

The prefix -- operator, --i, makes the preceding item current and returns an iterator pointing to the new current item.

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

See also operator++().

const_iterator const_iterator::operator--(int)

This is an overloaded function.

The postfix -- operator, i--, makes the preceding item current and returns an iterator pointing to the previously current item.

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

Makes the iterator go back by j items. If j is negative, the iterator goes forward.

This operation can be slow for large j values.

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

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

Returns a pointer to the current item.

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

Returns true if the item pointed to by this iterator is less than the item pointed to by the other iterator.

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

Returns true if the item pointed to by this iterator is less than or equal to the item pointed to by the other iterator.

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

Returns true if the item pointed to by this iterator is greater than the item pointed to by the other iterator.

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

Returns true if the item pointed to by this iterator is greater than or equal to the item pointed to by the other iterator.

const QJsonValueRef const_iterator::operator[](qsizetype j)

Returns the item at offset j from the item pointed to by this iterator (the item at position *this + j).

This function is provided to make QJsonObject iterators behave like C++ pointers.

See also operator+().