const_iterator Class Reference(QSet::const_iterator)The QSet::const_iterator class provides an STL-style const iterator for QSet. Далее... #include <QSet> Класс был добавлен в Qt 4.2. Открытые типы
Открытые функции
Подробное описаниеThe QSet::const_iterator class provides an STL-style const iterator for QSet. QSet features both STL-style iterators and Java-style iterators. The STL-style iterators are more low-level and more cumbersome to use; on the other hand, they are slightly faster and, for developers who already know STL, have the advantage of familiarity. QSet<Key, T>::const_iterator allows you to iterate over a QSet. If you want to modify the QSet as you iterate over it, you must use QSet::iterator instead. It is generally good practice to use QSet::const_iterator on a non-const QSet as well, unless you need to change the QSet through the iterator. Const iterators are slightly faster, and can improve code readability. The default QSet::const_iterator constructor creates an uninitialized iterator. You must initialize it using a function like QSet::begin(), QSet::end(), or QSet::insert() before you can start iterating. Here's a typical loop that prints all the items stored in a set: QSet<QString> set; set << "January" << "February" << ... << "December"; QSet<QString>::const_iterator i; for (i = set.begin(); i != set.end(); ++i) qDebug() << *i; STL-style iterators can be used as arguments to generic algorithms. For example, here's how to find an item in the set using the qFind() algorithm: QSet<QString> set; ... QSet<QString>::iterator it = qFind(set.begin(), set.end(), "Jeanette"); if (it != set.constEnd()) cout << "Found Jeanette" << endl; Multiple iterators can be used on the same set. However, you may not attempt to modify the container while iterating on it. See also QSet::iterator and QSetIterator. Описание типов-членовtypedef const_iterator::iterator_categorySynonyms for std::bidirectional_iterator_tag indicating these iterators are bidirectional iterators. Описание функций-членовconst_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. See also QSet::begin() and QSet::end(). const_iterator::const_iterator ( const const_iterator & other )Создаёт копию other. const_iterator::const_iterator ( const iterator & other )Это перегруженная функция. Создаёт копию other. Эта функция была введена в Qt 4.2. bool const_iterator::operator!= ( const const_iterator & other ) constReturns true if other points to a different item than this iterator; otherwise returns false. Смотрите также operator==(). const T & const_iterator::operator* () constReturns a reference to the current item. See also operator->(). const_iterator const_iterator::operator+ ( int j ) constReturns 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 (++it) advances the iterator to the next item in the set and returns an iterator to the new current item. Calling this function on QSet::constEnd() leads to undefined results. See also operator--(). const_iterator const_iterator::operator++ ( int )Это перегруженная функция. The postfix ++ operator (it++) advances the iterator to the next item in the set and returns an iterator to the previously current item. const_iterator & const_iterator::operator+= ( int 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- ( int j ) constReturns 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+(). 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 QSet::begin() leads to undefined results. See also operator++(). const_iterator const_iterator::operator-- ( int )Это перегруженная функция. The postfix -- operator (it--) makes the preceding item current and returns an iterator to the previously current item. const_iterator & const_iterator::operator-= ( int 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 T * const_iterator::operator-> () constReturns a pointer to the current item. See also operator*(). const_iterator & const_iterator::operator= ( const const_iterator & other )Assigns other to this iterator. bool const_iterator::operator== ( const const_iterator & other ) constReturns true if other points to the same item as this iterator; otherwise returns false. Смотрите также operator!=(). |
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