Qt 4.8
Public Types | Public Functions | Public Variables | List of all members
QList< T >::iterator Class Reference

The QList::iterator class provides an STL-style non-const iterator for QList and QQueue. More...

#include <qlist.h>

Public Types

typedef qptrdiff difference_type
 
typedef std::random_access_iterator_tag iterator_category
 A synonym for {std::random_access_iterator_tag} indicating this iterator is a random access iterator. More...
 
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...
 
iteratoroperator++ ()
 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...
 
iteratoroperator+= (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...
 
int operator- (iterator j) const
 Returns the number of items between the item pointed to by other and the item pointed to by this iterator. More...
 
iteratoroperator-- ()
 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...
 
iteratoroperator-= (int j)
 Makes the iterator go back by j items. More...
 
T * operator-> () const
 Returns a pointer to the current item. More...
 
bool operator< (const iterator &other) const
 Returns true if the item pointed to by this iterator is less than the item pointed to by the other iterator. More...
 
bool operator< (const const_iterator &other) const
 
bool operator<= (const iterator &other) const
 Returns true if the item pointed to by this iterator is less than or equal to the item pointed to by the other iterator. More...
 
bool operator<= (const const_iterator &other) const
 
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
 
bool operator> (const iterator &other) const
 Returns true if the item pointed to by this iterator is greater than the item pointed to by the other iterator. More...
 
bool operator> (const const_iterator &other) const
 
bool operator>= (const iterator &other) const
 Returns true if the item pointed to by this iterator is greater than or equal to the item pointed to by the other iterator. More...
 
bool operator>= (const const_iterator &other) const
 
T & operator[] (int j) const
 Returns a modifiable reference to the item at position *this + {j}. More...
 

Public Variables

Nodei
 

Detailed Description

template<typename T>
class QList< T >::iterator

The QList::iterator class provides an STL-style non-const iterator for QList and QQueue.

QList 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.

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

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

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

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

for (i = list.begin(); i != list.end(); ++i)
*i += 2;

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

For example, here's how to delete all the widgets stored in a QList<QWidget *>:

...
qDeleteAll(list.begin(), list.end());

Multiple iterators can be used on the same list. However, be aware that any non-const function call performed on the QList will render all existing iterators undefined. If you need to keep iterators over a long period of time, we recommend that you use QLinkedList rather than QList.

See also
QList::const_iterator, QMutableListIterator

Definition at line 181 of file qlist.h.

Typedefs

◆ difference_type

template<typename T>
QList< T >::iterator::difference_type
Warning
This function is not part of the public interface.

Definition at line 185 of file qlist.h.

◆ iterator_category

template<typename T>
QList< T >::iterator::iterator_category

A synonym for {std::random_access_iterator_tag} indicating this iterator is a random access iterator.

Definition at line 184 of file qlist.h.

◆ pointer

template<typename T>
QList< T >::iterator::pointer
Warning
This function is not part of the public interface.

Definition at line 187 of file qlist.h.

◆ reference

template<typename T>
QList< T >::iterator::reference
Warning
This function is not part of the public interface.

Definition at line 188 of file qlist.h.

◆ value_type

template<typename T>
QList< T >::iterator::value_type
Warning
This function is not part of the public interface.

Definition at line 186 of file qlist.h.

Constructors and Destructors

◆ iterator() [1/3]

template<typename T>
QList< 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
QList::begin() QList::end()

Definition at line 190 of file qlist.h.

190 : i(0) {}
Node * i
Definition: qlist.h:183

◆ iterator() [2/3]

template<typename T>
QList< T >::iterator::iterator ( Node node)
inline
Warning
This function is not part of the public interface.

Definition at line 191 of file qlist.h.

191 : i(n) {}
Node * i
Definition: qlist.h:183

◆ iterator() [3/3]

template<typename T>
QList< T >::iterator::iterator ( const iterator o)
inline

Constructs a copy of other.

Definition at line 192 of file qlist.h.

192 : i(o.i){}
Node * i
Definition: qlist.h:183

Functions

◆ operator!=() [1/2]

template<typename T>
bool QList< T >::iterator::operator!= ( const iterator o) const
inline

Returns true if other points to a different item than this iterator; otherwise returns false.

Definition at line 197 of file qlist.h.

197 { return i != o.i; }
Node * i
Definition: qlist.h:183

◆ operator!=() [2/2]

template<typename T>
bool QList< T >::iterator::operator!= ( const const_iterator other) const
inline
See also
operator==()

Definition at line 205 of file qlist.h.

206  { return i != o.i; }
Node * i
Definition: qlist.h:183

◆ operator*()

template<typename T>
T & QList< T >::iterator::operator* ( ) const
inline

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, for example:

if (*it == "Hello")
*it = "Bonjour";
See also
operator->()

Definition at line 193 of file qlist.h.

193 { return i->t(); }
Q_INLINE_TEMPLATE T & t()
Definition: qlist.h:112
Node * i
Definition: qlist.h:183

◆ operator+()

template<typename T>
QList::iterator QList< T >::iterator::operator+ ( int  j) const
inline

Returns an iterator to the item at j positions forward from this iterator.

(If j is negative, the iterator goes backward.)

See also
operator-(), operator+=()

Definition at line 222 of file qlist.h.

222 { return iterator(i+j); }
iterator()
Constructs an uninitialized iterator.
Definition: qlist.h:190
Node * i
Definition: qlist.h:183

◆ operator++() [1/2]

template<typename T>
QList::iterator & QList< T >::iterator::operator++ ( )
inline

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

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

See also
operator--()

Definition at line 216 of file qlist.h.

216 { ++i; return *this; }
Node * i
Definition: qlist.h:183

◆ operator++() [2/2]

template<typename T>
QList::iterator QList< T >::iterator::operator++ ( int  )
inline

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

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 217 of file qlist.h.

217 { Node *n = i; ++i; return n; }
Node * i
Definition: qlist.h:183

◆ operator+=()

template<typename T>
QList::iterator & QList< T >::iterator::operator+= ( int  j)
inline

Advances the iterator by j items.

(If j is negative, the iterator goes backward.)

See also
operator-=(), operator+()

Definition at line 220 of file qlist.h.

220 { i+=j; return *this; }
Node * i
Definition: qlist.h:183

◆ operator-() [1/2]

template<typename T>
QList::iterator QList< T >::iterator::operator- ( int  j) const
inline

Returns an iterator to the item at j positions backward from this iterator.

(If j is negative, the iterator goes forward.)

See also
operator+(), operator-=()

Definition at line 223 of file qlist.h.

223 { return iterator(i-j); }
iterator()
Constructs an uninitialized iterator.
Definition: qlist.h:190
Node * i
Definition: qlist.h:183

◆ operator-() [2/2]

template<typename T>
int QList< T >::iterator::operator- ( iterator  j) const
inline

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

Definition at line 224 of file qlist.h.

224 { return int(i - j.i); }
Node * i
Definition: qlist.h:183

◆ operator--() [1/2]

template<typename T>
QList::iterator & QList< T >::iterator::operator-- ( )
inline

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

Calling this function on QList::begin() leads to undefined results.

See also
operator++()

Definition at line 218 of file qlist.h.

218 { i--; return *this; }
Node * i
Definition: qlist.h:183

◆ operator--() [2/2]

template<typename T>
QList::iterator QList< T >::iterator::operator-- ( int  )
inline

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

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 219 of file qlist.h.

219 { Node *n = i; i--; return n; }
Node * i
Definition: qlist.h:183

◆ operator-=()

template<typename T>
QList::iterator & QList< T >::iterator::operator-= ( int  j)
inline

Makes the iterator go back by j items.

(If j is negative, the iterator goes forward.)

See also
operator+=(), operator-()

Definition at line 221 of file qlist.h.

221 { i-=j; return *this; }
Node * i
Definition: qlist.h:183

◆ operator->()

template<typename T>
T * QList< T >::iterator::operator-> ( ) const
inline

Returns a pointer to the current item.

See also
operator*()

Definition at line 194 of file qlist.h.

194 { return &i->t(); }
Q_INLINE_TEMPLATE T & t()
Definition: qlist.h:112
Node * i
Definition: qlist.h:183

◆ operator<() [1/2]

template<typename T>
bool QList< T >::iterator::operator< ( const iterator other) const
inline

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

Definition at line 198 of file qlist.h.

198 { return i < other.i; }
Node * i
Definition: qlist.h:183

◆ operator<() [2/2]

template<typename T>
bool QList< T >::iterator::operator< ( const const_iterator other) const
inline

Definition at line 207 of file qlist.h.

208  { return i < other.i; }
Node * i
Definition: qlist.h:183

◆ operator<=() [1/2]

template<typename T>
bool QList< T >::iterator::operator<= ( const iterator other) const
inline

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

Definition at line 199 of file qlist.h.

199 { return i <= other.i; }
Node * i
Definition: qlist.h:183

◆ operator<=() [2/2]

template<typename T>
bool QList< T >::iterator::operator<= ( const const_iterator other) const
inline

Definition at line 209 of file qlist.h.

210  { return i <= other.i; }
Node * i
Definition: qlist.h:183

◆ operator==() [1/2]

template<typename T>
bool QList< T >::iterator::operator== ( const iterator o) const
inline

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

Definition at line 196 of file qlist.h.

196 { return i == o.i; }
Node * i
Definition: qlist.h:183

◆ operator==() [2/2]

template<typename T>
bool QList< T >::iterator::operator== ( const const_iterator other) const
inline
See also
operator!=()

Definition at line 203 of file qlist.h.

204  { return i == o.i; }
Node * i
Definition: qlist.h:183

◆ operator>() [1/2]

template<typename T>
bool QList< T >::iterator::operator> ( const iterator other) const
inline

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

Definition at line 200 of file qlist.h.

200 { return i > other.i; }
Node * i
Definition: qlist.h:183

◆ operator>() [2/2]

template<typename T>
bool QList< T >::iterator::operator> ( const const_iterator other) const
inline

Definition at line 211 of file qlist.h.

212  { return i > other.i; }
Node * i
Definition: qlist.h:183

◆ operator>=() [1/2]

template<typename T>
bool QList< T >::iterator::operator>= ( const iterator other) const
inline

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

Definition at line 201 of file qlist.h.

201 { return i >= other.i; }
Node * i
Definition: qlist.h:183

◆ operator>=() [2/2]

template<typename T>
bool QList< T >::iterator::operator>= ( const const_iterator other) const
inline

Definition at line 213 of file qlist.h.

214  { return i >= other.i; }
Node * i
Definition: qlist.h:183

◆ operator[]()

template<typename T>
T & QList< T >::iterator::operator[] ( int  j) const
inline

Returns a modifiable reference to the item at position *this + {j}.

This function is provided to make QList iterators behave like C++ pointers.

See also
operator+()

Definition at line 195 of file qlist.h.

195 { return i[j].t(); }
Q_INLINE_TEMPLATE T & t()
Definition: qlist.h:112
Node * i
Definition: qlist.h:183

Properties

◆ i

template<typename T>
Node* QList< T >::iterator::i

The documentation for this class was generated from the following files: