就业培训     下载中心     Wiki     联络
登录   注册
  1. 首页
  2. Qt 6.8.5
  3. Qt Core
  4. C++ 类
  5. const_iterator

const_iterator 类

class QJsonArray ::const_iterator

The QJsonArray::const_iterator 类提供 STL 样式 const 迭代器为 QJsonArray . 更多...

此类 强烈可比较 .

此类 强烈可比较 with QJsonArray::iterator .

公共类型

iterator_category

公共函数

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

详细描述

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

默认 QJsonArray::const_iterator constructor creates an uninitialized iterator. You must initialize it using a QJsonArray function like QJsonArray::constBegin (), QJsonArray::constEnd ()，或 QJsonArray::insert () before you can start iterating.

Most QJsonArray functions accept an integer index rather than an iterator. For that reason, iterators are rarely useful in connection with QJsonArray . One place where STL-style iterators do make sense is as arguments to 一般算法 .

Multiple iterators can be used on the same array. However, be aware that any non-const function call performed on the QJsonArray will render all existing iterators undefined.

另请参阅 QJsonArray::iterator .

成员类型文档编制

const_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

const_iterator:: const_iterator ()

Constructs an uninitialized iterator.

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

另请参阅 QJsonArray::constBegin () 和 QJsonArray::constEnd ().

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

构造副本为 other .

const QJsonValueConstRef const_iterator:: operator* () const

返回当前项。

QJsonArray::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.

另请参阅 operator- () 和 operator+= ().

QJsonArray::const_iterator &const_iterator:: operator++ ()

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

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

另请参阅 operator-- ().

QJsonArray::const_iterator const_iterator:: operator++ ( int )

这是重载函数。

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

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

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

另请参阅 operator-= () 和 operator+ ().

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

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

QJsonArray::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.

另请参阅 operator+ () 和 operator-= ().

QJsonArray::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 QJsonArray::begin () leads to undefined results.

另请参阅 operator++ ().

QJsonArray::const_iterator const_iterator:: operator-- ( int )

这是重载函数。

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

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

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

另请参阅 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 QJsonArray iterators behave like C++ pointers.

另请参阅 operator+ ().

相关非成员

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

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

另请参阅 operator== ().

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

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

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

返回 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 QJsonArray::const_iterator & lhs , const QJsonArray::const_iterator & rhs )

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

另请参阅 operator!= ().

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

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

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

返回 true if the item pointed to by lhs iterator is greater than or equal to the item 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