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  2. Qt 6.8.5
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  4. C++ 类
  5. 迭代器

Iterator 类

class QCborMap ::Iterator

The QCborMap::Iterator 类提供 STL 样式非常量迭代器为 QCborMap . 更多...

此类 强烈可比较 .

此类 强烈可比较 with ConstIterator .

公共类型

iterator_category

公共函数

Iterator ()
Iterator (const QCborMap::Iterator & other )
QCborValue key () const
QCborValueRef value () const
QCborMap::Iterator::value_type operator* () const
QCborMap::Iterator operator+ (qsizetype j ) const
QCborMap::Iterator & operator++ ()
QCborMap::Iterator operator++ (int)
QCborMap::Iterator & operator+= (qsizetype j )
qsizetype operator- (QCborMap::Iterator j ) const
QCborMap::Iterator operator- (qsizetype j ) const
QCborMap::Iterator & operator-- ()
QCborMap::Iterator operator-- (int)
QCborMap::Iterator & operator-= (qsizetype j )
const QCborValueConstRef * operator-> () const
QCborMap::Iterator & operator= (const QCborMap::Iterator & other )
bool operator!= (const QCborMap::Iterator & lhs , const QCborMap::ConstIterator & rhs )
bool operator!= (const QCborMap::Iterator & lhs , const QCborMap::Iterator & rhs )
bool operator< (const QCborMap::Iterator & lhs , const QCborMap::ConstIterator & rhs )
bool operator< (const QCborMap::Iterator & lhs , const QCborMap::Iterator & rhs )
bool operator<= (const QCborMap::Iterator & lhs , const QCborMap::ConstIterator & rhs )
bool operator<= (const QCborMap::Iterator & lhs , const QCborMap::Iterator & rhs )
bool operator== (const QCborMap::Iterator & lhs , const QCborMap::ConstIterator & rhs )
bool operator== (const QCborMap::Iterator & lhs , const QCborMap::Iterator & rhs )
bool operator> (const QCborMap::Iterator & lhs , const QCborMap::ConstIterator & rhs )
bool operator> (const QCborMap::Iterator & lhs , const QCborMap::Iterator & rhs )
bool operator>= (const QCborMap::Iterator & lhs , const QCborMap::ConstIterator & rhs )
bool operator>= (const QCborMap::Iterator & lhs , const QCborMap::Iterator & rhs )

详细描述

QCborMap::Iterator allows you to iterate over a QCborMap and to modify the value (but not the key) stored under a particular key. If you want to iterate over a const QCborMap , you should use QCborMap::ConstIterator . It is generally good practice to use QCborMap::ConstIterator on a non-const QCborMap as well, unless you need to change the QCborMap through the iterator. Const iterators are slightly faster, and improve code readability.

You must initialize the iterator using a QCborMap function like QCborMap::begin (), QCborMap::end ()，或 QCborMap::find () before you can start iterating..

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

另请参阅 QCborMap::ConstIterator .

成员类型文档编制

Iterator:: iterator_category

同义词 std::random_access_iterator_tag indicating this iterator is a random-access iterator.

成员函数文档编制

[constexpr noexcept] Iterator:: 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.

另请参阅 QCborMap::begin () 和 QCborMap::end ().

[constexpr noexcept] Iterator:: Iterator (const QCborMap::Iterator & other )

Constructs an iterator as a copy of other .

QCborValue Iterator:: key () const

Returns the current item's key.

There is no direct way of changing an item's key through an iterator, although it can be done by calling QCborMap::erase () followed by QCborMap::insert ().

另请参阅 value ().

QCborValueRef Iterator:: value () const

Returns a modifiable reference to the current item's value.

You can change the value for a key by using value() on the left side of an assignment.

The return value is of type QCborValueRef, a helper class for QCborArray and QCborMap . When you get an object of type QCborValueRef, you can use it as if it were a reference to a QCborValue . If you assign to it, the assignment will apply to the element in the QCborArray or QCborMap from which you got the reference.

另请参阅 key () 和 operator* ().

QCborMap::Iterator::value_type Iterator:: operator* () const

Returns a pair containing the current item's key and a modifiable reference to the current item's value.

The second element of the pair is of type QCborValueRef, a helper class for QCborArray and QCborMap . When you get an object of type QCborValueRef, you can use it as if it were a reference to a QCborValue . If you assign to it, the assignment will apply to the element in the QCborArray or QCborMap from which you got the reference.

另请参阅 key () 和 value ().

QCborMap::Iterator 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.

另请参阅 operator- ().

QCborMap::Iterator &Iterator:: operator++ ()

The prefix ++ operator, ++i , advances the iterator to the next item in the map and returns this iterator.

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

另请参阅 operator-- ().

QCborMap::Iterator Iterator:: operator++ ( int )

这是重载函数。

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

QCborMap::Iterator &Iterator:: operator+= ( qsizetype j )

Advances the iterator by j items. If j is negative, the iterator goes backward. Returns a reference to this iterator.

另请参阅 operator-= () 和 operator+ ().

qsizetype Iterator:: operator- ( QCborMap::Iterator j ) const

Returns the position of the item at iterator j relative to the item at this iterator. If the item at j is forward of this time, the returned value is negative.

另请参阅 operator+ ().

QCborMap::Iterator 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.

另请参阅 operator+ ().

QCborMap::Iterator &Iterator:: operator-- ()

The prefix -- operator, --i , makes the preceding item current and returns this iterator.

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

另请参阅 operator++ ().

QCborMap::Iterator Iterator:: operator-- ( int )

这是重载函数。

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

QCborMap::Iterator &Iterator:: operator-= ( qsizetype j )

Makes the iterator go back by j items. If j is negative, the iterator goes forward. Returns a reference to this iterator.

另请参阅 operator+= () 和 operator- ().

const QCborValueConstRef *Iterator:: operator-> () const

Returns a pointer to a modifiable reference to the current pair's value.

QCborMap::Iterator &Iterator:: operator= (const QCborMap::Iterator & other )

Makes this iterator a copy of other and returns a reference to this iterator.

相关非成员

[noexcept] bool operator== (const QCborMap::Iterator & lhs , const QCborMap::ConstIterator & rhs )

[noexcept] bool operator== (const QCborMap::Iterator & lhs , const QCborMap::Iterator & rhs )

返回 true if lhs points to the same entry in the map as rhs iterator; otherwise returns false .

另请参阅 operator!= ().

[noexcept] bool operator!= (const QCborMap::Iterator & lhs , const QCborMap::ConstIterator & rhs )

[noexcept] bool operator!= (const QCborMap::Iterator & lhs , const QCborMap::Iterator & rhs )

返回 true if lhs points to a different entry in the map than rhs iterator; otherwise returns false .

另请参阅 operator== ().

[noexcept] bool operator< (const QCborMap::Iterator & lhs , const QCborMap::ConstIterator & rhs )

[noexcept] bool operator< (const QCborMap::Iterator & lhs , const QCborMap::Iterator & rhs )

返回 true if the entry in the map pointed to by lhs iterator occurs before the entry pointed to by the rhs iterator.

[noexcept] bool operator<= (const QCborMap::Iterator & lhs , const QCborMap::ConstIterator & rhs )

[noexcept] bool operator<= (const QCborMap::Iterator & lhs , const QCborMap::Iterator & rhs )

返回 true if the entry in the map pointed to by lhs iterator occurs before or is the same entry as is pointed to by the rhs iterator.

[noexcept] bool operator> (const QCborMap::Iterator & lhs , const QCborMap::ConstIterator & rhs )

[noexcept] bool operator> (const QCborMap::Iterator & lhs , const QCborMap::Iterator & rhs )

返回 true if the entry in the map pointed to by lhs iterator occurs after the entry pointed to by the rhs iterator.

[noexcept] bool operator>= (const QCborMap::Iterator & lhs , const QCborMap::ConstIterator & rhs )

[noexcept] bool operator>= (const QCborMap::Iterator & lhs , const QCborMap::Iterator & rhs )

返回 true if the entry in the map pointed to by lhs iterator occurs after or is the same entry as is pointed to by the rhs iterator.

内容

  1. 公共类型

  2. 公共函数

  3. 相关非成员

  4. 详细描述