iterator 类

( QJsonArray::iterator )

The QJsonArray::iterator 类提供 STL 样式非常量迭代器为 QJsonArray . 更多...

头: #include <iterator>
qmake: QT += core

公共类型

typedef iterator_category

公共函数

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

公共变量

QJsonArray * a
int i

详细描述

The QJsonArray::iterator 类提供 STL 样式非常量迭代器为 QJsonArray .

QJsonArray::iterator allows you to iterate over a QJsonArray and to modify the array item associated with the iterator. If you want to iterate over a const QJsonArray ,使用 QJsonArray::const_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::iterator constructor creates an uninitialized iterator. You must initialize it using a QJsonArray function like QJsonArray::begin (), QJsonArray::end (),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::const_iterator .

成员类型文档编制

typedef 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

返回 true if other 指向与此迭代器不同的项;否则返回 false .

另请参阅 operator== ().

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

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

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

另请参阅 operator!= ().

iterator:: 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::begin () 和 QJsonArray::end ().

QJsonValueRef iterator:: operator* () const

Returns a modifiable reference to the current item.

You can change the value of an item by using operator*() on the left side of an assignment.

The return value is of type QJsonValueRef , a helper class for QJsonArray and QJsonObject . When you get an object of type QJsonValueRef , you can use it as if it were a reference to a QJsonValue . If you assign to it, the assignment will apply to the character in the QJsonArray of QJsonObject from which you got the reference.

iterator iterator:: operator+ ( int 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+= ().

iterator &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-- ().

iterator 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.

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

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

另请参阅 operator-= () 和 operator+ ().

iterator iterator:: operator- ( int 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-= ().

int iterator:: operator- ( iterator other ) const

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

iterator &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++ ().

iterator 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.

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

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

另请参阅 operator+= () 和 operator- ().

QJsonValueRef *iterator:: operator-> () const

Returns a pointer to a modifiable reference to the current item.

QJsonValueRef iterator:: operator[] ( int j ) const

Returns a modifiable reference to 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.

The return value is of type QJsonValueRef , a helper class for QJsonArray and QJsonObject . When you get an object of type QJsonValueRef , you can use it as if it were a reference to a QJsonValue . If you assign to it, the assignment will apply to the character in the QJsonArray of QJsonObject from which you got the reference.

另请参阅 operator+ ().