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  5. const_iterator

const_iterator 類

class QJsonObject ::const_iterator

The QJsonObject::const_iterator 類提供 STL 樣式 const 迭代器為 QJsonObject . 更多...

此類 強烈可比較 .

此類 強烈可比較 with QJsonObject::iterator .

公共類型

iterator_category

公共函數

const_iterator ()
const_iterator (const QJsonObject::iterator & other )
QString key () const
QJsonValueConstRef value () const
const QJsonValueConstRef operator* () const
QJsonObject::const_iterator operator+ (qsizetype j ) const
QJsonObject::const_iterator & operator++ ()
QJsonObject::const_iterator operator++ (int)
QJsonObject::const_iterator & operator+= (qsizetype j )
qsizetype operator- (QJsonObject::const_iterator other ) const
QJsonObject::const_iterator operator- (qsizetype j ) const
QJsonObject::const_iterator & operator-- ()
QJsonObject::const_iterator operator-- (int)
QJsonObject::const_iterator & operator-= (qsizetype j )
const QJsonValueConstRef * operator-> () const
QJsonValueConstRef operator[] (qsizetype j ) const
bool operator!= (const QJsonObject::const_iterator & lhs , const QJsonObject::const_iterator & rhs )
bool operator< (const QJsonObject::const_iterator & lhs , const QJsonObject::const_iterator & rhs )
bool operator<= (const QJsonObject::const_iterator & lhs , const QJsonObject::const_iterator & rhs )
bool operator== (const QJsonObject::const_iterator & lhs , const QJsonObject::const_iterator & rhs )
bool operator> (const QJsonObject::const_iterator & lhs , const QJsonObject::const_iterator & rhs )
bool operator>= (const QJsonObject::const_iterator & lhs , const QJsonObject::const_iterator & rhs )

詳細描述

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.

默認 QJsonObject::const_iterator constructor creates an uninitialized iterator. You must initialize it using a QJsonObject function like QJsonObject::constBegin (), QJsonObject::constEnd ()，或 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.

另請參閱 QJsonObject::iterator , 在 Qt 中支持 JSON ，和 保存和加載遊戲 .

成員類型文檔編製

const_iterator:: iterator_category

同義詞 std::random_access_iterator_tag indicating this iterator is a random-access iterator.

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

成員函數文檔編製

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.

另請參閱 QJsonObject::constBegin () 和 QJsonObject::constEnd ().

const_iterator:: const_iterator (const QJsonObject::iterator & other )

構造副本為 other .

QString const_iterator:: key () const

Returns the current item's key.

另請參閱 value ().

QJsonValueConstRef const_iterator:: value () const

Returns the current item's value.

另請參閱 key () 和 operator* ().

const QJsonValueConstRef const_iterator:: operator* () const

Returns the current item's value.

如同 value ().

另請參閱 key ().

QJsonObject::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 值。

另請參閱 operator- ().

QJsonObject::const_iterator &const_iterator:: operator++ ()

前綴 ++ 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.

另請參閱 operator-- ().

QJsonObject::const_iterator const_iterator:: operator++ ( int )

這是重載函數。

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

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

推進迭代器 j items. If j is negative, the iterator goes backward.

This operation can be slow for large j 值。

另請參閱 operator-= () 和 operator+ ().

qsizetype const_iterator:: operator- ( QJsonObject::const_iterator other ) const

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

QJsonObject::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 值。

另請參閱 operator+ ().

QJsonObject::const_iterator &const_iterator:: operator-- ()

前綴 -- 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.

另請參閱 operator++ ().

QJsonObject::const_iterator const_iterator:: operator-- ( int )

這是重載函數。

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

QJsonObject::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 值。

另請參閱 operator+= () 和 operator- ().

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

Returns a pointer to the current item.

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

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.

另請參閱 operator+ ().

相關非成員

[noexcept] bool operator!= (const QJsonObject::const_iterator & lhs , const QJsonObject::const_iterator & rhs )

返迴 true if lhs points to a different item than rhs iterator; otherwise returns false .

另請參閱 operator== ().

[noexcept] bool operator< (const QJsonObject::const_iterator & lhs , const QJsonObject::const_iterator & rhs )

返迴 true if the item pointed to by lhs iterator is less than the item pointed to by the rhs iterator.

[noexcept] bool operator<= (const QJsonObject::const_iterator & lhs , const QJsonObject::const_iterator & rhs )

返迴 true if the item pointed to by lhs iterator is less than or equal to the item pointed to by the rhs iterator.

[noexcept] bool operator== (const QJsonObject::const_iterator & lhs , const QJsonObject::const_iterator & rhs )

返迴 true if lhs points to the same item as rhs iterator; otherwise returns false .

另請參閱 operator!= ().

[noexcept] bool operator> (const QJsonObject::const_iterator & lhs , const QJsonObject::const_iterator & rhs )

返迴 true if the item pointed to by lhs iterator is greater than the item pointed to by the rhs iterator.

[noexcept] bool operator>= (const QJsonObject::const_iterator & lhs , const QJsonObject::const_iterator & rhs )

返迴 true if the item pointed to by lhs iterator is greater than or equal to the item pointed to by the rhs iterator.

內容

  1. 公共類型

  2. 公共函數

  3. 相關非成員

  4. 詳細描述