const_iterator Class

The https:// class provides an STL-style const iterator for https://.

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Publié le 27 décembre 2024 - Mis à jour le 27 décembre 2024

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const_iterator Class▲

Header: const_iterator
qmake: QT += core

Detailed Description▲

https:// features both https:// and https://. 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.

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

The default https:// constructor creates an uninitialized iterator. You must initialize it using a function like QLinkedList::constBegin(), QLinkedList::constEnd(), or QLinkedList::insert() before you can start iterating. Here's a typical loop that prints all the items stored in a list:

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QLinkedList&lt;QString&gt; list;
list.append("January");
list.append("February");
...
list.append("December");

QLinkedList&lt;QString&gt;::const_iterator i;
for (i = list.constBegin(); i != list.constEnd(); ++i)
    cout &lt;&lt; *i &lt;&lt; endl;

STL-style iterators can be used as arguments to https://. For example, here's how to find an item in the list using the qFind() algorithm:

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QLinkedList&lt;QString&gt; list;
...
QLinkedList&lt;QString&gt;::iterator it = qFind(list.constBegin(),
                                          list.constEnd(), "Joel");
if (it != list.constEnd())
    cout &lt;&lt; "Found Joel" &lt;&lt; endl;

Multiple iterators can be used on the same list. If you add items to the list, existing iterators will remain valid. If you remove items from the list, iterators that point to the removed items will become dangling iterators.

Iterators on implicitly shared containers do not work exactly like STL-iterators. You should avoid copying a container while iterators are active on that container. For more information, read https://.

Member Function Documentation▲

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.

const_iterator::const_iterator(iterator other)▲

Constructs a copy of other.

const_iterator::const_iterator(const const_iterator &other)▲