The QLinkedList::iterator class provides an STL-style non-const iterator for QLinkedList. More...

#include <qlinkedlist.h>

Public Types
typedef qptrdiff	difference_type

typedef std::bidirectional_iterator_tag	iterator_category

typedef T *	pointer

typedef T &	reference

typedef T	value_type

Public Functions
	iterator ()
	Constructs an uninitialized iterator. More...

	iterator (Node *n)

	iterator (const iterator &o)
	Constructs a copy of other. More...

bool	operator!= (const iterator &o) const
	Returns true if other points to a different item than this iterator; otherwise returns false. More...

bool	operator!= (const const_iterator &o) const

T &	operator* () const
	Returns a modifiable reference to the current item. More...

iterator	operator+ (int j) const
	Returns an iterator to the item at j positions forward from this iterator. More...

iterator &	operator++ ()
	The prefix ++ operator (`++it`) advances the iterator to the next item in the list and returns an iterator to the new current item. More...

iterator	operator++ (int)
	The postfix ++ operator (`it++`) advances the iterator to the next item in the list and returns an iterator to the previously current item. More...

iterator &	operator+= (int j)
	Advances the iterator by j items. More...

iterator	operator- (int j) const
	Returns an iterator to the item at j positions backward from this iterator. More...

iterator &	operator-- ()
	The prefix – operator (`–it`) makes the preceding item current and returns an iterator to the new current item. More...

iterator	operator-- (int)
	The postfix – operator (`it–`) makes the preceding item current and returns an iterator to the previously current item. More...

iterator &	operator-= (int j)
	Makes the iterator go back by j items. More...

T *	operator-> () const
	Returns a pointer to the current item. More...

iterator &	operator= (const iterator &o)
	Assigns other to this iterator. More...

bool	operator== (const iterator &o) const
	Returns true if other points to the same item as this iterator; otherwise returns false. More...

bool	operator== (const const_iterator &o) const

Public Variables
Node *	i

Detailed Description

template<class T>
class QLinkedList< T >::iterator

The QLinkedList::iterator class provides an STL-style non-const iterator for QLinkedList.

QLinkedList 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.

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

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

QLinkedList<QString> list;
list.append("January");
list.append("February");
...
list.append("December");
QLinkedList<QString>::iterator i;
for (i = list.begin(); i != list.end(); ++i)
    cout << *i << endl;

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

QLinkedList<QString> list;
...
QLinkedList<QString>::iterator it = qFind(list.begin(),
                                          list.end(), "Joel");
if (it != list.end())
    cout << "Found Joel" << endl;

Let's see a few examples of things we can do with a QLinkedList::iterator that we cannot do with a QLinkedList::const_iterator. Here's an example that increments every value stored in a QLinkedList<int> by 2:

QLinkedList<int>::iterator i;
for (i = list.begin(); i != list.end(); ++i)
    *i += 2;

Here's an example that removes all the items that start with an underscore character in a QLinkedList<QString>:

QLinkedList<QString> list;
...
QLinkedList<QString>::iterator i = list.begin();
while (i != list.end()) {
    if ((*i).startsWith("_"))
        i = list.erase(i);
    else
        ++i;
}

The call to QLinkedList::erase() removes the item pointed to by the iterator from the list, and returns an iterator to the next item. Here's another way of removing an item while iterating:

QLinkedList<QString>::iterator i = list.begin();
while (i != list.end()) {
    QLinkedList<QString>::iterator previous = i;
    ++i;
    if ((*previous).startsWith("_"))
        list.erase(previous);
}

It might be tempting to write code like this:

// WRONG
while (i != list.end()) {
    if ((*i).startsWith("_"))
        list.erase(i);
    ++i;
}

However, this will potentially crash in ++i, because i is a dangling iterator after the call to erase().

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. However, because of how implicit sharing works, you must not take a copy of a container while iterators are active on that container.

See also: QLinkedList::const_iterator, QMutableLinkedListIterator

Definition at line 118 of file qlinkedlist.h.

Typedefs

◆ difference_type

template<class T>

QLinkedList< T >::iterator::difference_type

Warning: This function is not part of the public interface.

Definition at line 122 of file qlinkedlist.h.

◆ iterator_category

template<class T>

QLinkedList< T >::iterator::iterator_category

Warning: This function is not part of the public interface.

Definition at line 121 of file qlinkedlist.h.

◆ pointer

template<class T>

QLinkedList< T >::iterator::pointer

Warning: This function is not part of the public interface.

Definition at line 124 of file qlinkedlist.h.

◆ reference

template<class T>

QLinkedList< T >::iterator::reference

Warning: This function is not part of the public interface.

Definition at line 125 of file qlinkedlist.h.

◆ value_type

template<class T>

QLinkedList< T >::iterator::value_type

Warning: This function is not part of the public interface.

Definition at line 123 of file qlinkedlist.h.

Constructors and Destructors

◆ iterator() [1/3]

template<class T>

QLinkedList< T >::iterator::iterator ( )

inline

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: QLinkedList::begin() QLinkedList::end()

Definition at line 127 of file qlinkedlist.h.

127 : i(0) {}

Public Types

Public Functions

Public Variables

Detailed Description

template<class T> class QLinkedList< T >::iterator

Typedefs

◆ difference_type

◆ iterator_category

◆ pointer

◆ reference

◆ value_type

Constructors and Destructors

◆ iterator() [1/3]

◆ iterator() [2/3]

◆ iterator() [3/3]

Functions

◆ operator!=() [1/2]

◆ operator!=() [2/2]

◆ operator*()

◆ operator+()

◆ operator++() [1/2]

◆ operator++() [2/2]

◆ operator+=()

◆ operator-()

◆ operator--() [1/2]

◆ operator--() [2/2]

◆ operator-=()

◆ operator->()

◆ operator=()

◆ operator==() [1/2]

◆ operator==() [2/2]

Properties

◆ i

template<class T>
class QLinkedList< T >::iterator