QValueListIterator(3qt) QValueListIterator(3qt)
NAME
QValueListIterator - Iterator for QValueList
SYNOPSIS
All the functions in this class are reentrant when Qt is built with thread support.</p>
#include <qvaluelist.h>
Public Members
typedef T value_type
typedef T * pointer
typedef T & reference
QValueListIterator ()
QValueListIterator ( const QValueListIterator<T> & it )
bool operator== ( const QValueListIterator<T> & it ) const
bool operator!= ( const QValueListIterator<T> & it ) const
const T & operator* () const
T & operator* ()
QValueListIterator<T> & operator++ ()
QValueListIterator<T> operator++ ( int )
QValueListIterator<T> & operator-- ()
QValueListIterator<T> operator-- ( int )
QValueListIterator<T> & operator+= ( int j )
QValueListIterator<T> & operator-= ( int j )
DESCRIPTION
The QValueListIterator class provides an iterator for QValueList.
An iterator is a class for accessing the items of a container class: a generalization of the index in an array. A pointer into a "const
char *" and an index into an "int[]" are both iterators, and the general idea is to provide that functionality for any data structure.
The QValueListIterator class is an iterator for QValueList instantiations. You can create the appropriate iterator type by using the
iterator typedef provided by QValueList.
The only way to access the items in a QValueList is to use an iterator.
Example (see QValueList for the complete code):
EmployeeList::iterator it;
for ( it = list.begin(); it != list.end(); ++it )
cout << (*it).surname().latin1() << ", " <<
(*it).forename().latin1() << " earns " <<
(*it).salary() << endl;
// Output:
// Doe, John earns 50000
// Williams, Jane earns 80000
// Hawthorne, Mary earns 90000
// Jones, Tom earns 60000
QValueList is highly optimized for performance and memory usage. This means that you must be careful: QValueList does not know about all
its iterators and the iterators don't know to which list they belong. This makes things very fast, but if you're not careful, you can get
spectacular bugs. Always make sure iterators are valid before dereferencing them or using them as parameters to generic algorithms in the
STL or the QTL.
Using an invalid iterator is undefined (your application will probably crash). Many Qt functions return const value lists; to iterate over
these you should make a copy and iterate over the copy.
For every Iterator there is a ConstIterator. When accessing a QValueList in a const environment or if the reference or pointer to the list
is itself const, then you must use the ConstIterator. Its semantics are the same as the Iterator, but it only returns const references.
See also QValueList, QValueListConstIterator, Qt Template Library Classes, and Non-GUI Classes.
Member Type Documentation
QValueListIterator::pointer
Pointer to value_type.
QValueListIterator::reference
Reference to value_type.
QValueListIterator::value_type
The type of value, T.
MEMBER FUNCTION DOCUMENTATION
QValueListIterator::QValueListIterator ()
Creates un uninitialized iterator.
QValueListIterator::QValueListIterator ( const QValueListIterator<T> & it )
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
Constructs a copy of the iterator it.
bool QValueListIterator::operator!= ( const QValueListIterator<T> & it ) const
Compares this iterator and it and returns TRUE if they point to different items; otherwise returns FALSE.
T &; QValueListIterator::operator* ()
Asterisk operator. Returns a reference to the current iterator item.
const T &; QValueListIterator::operator* () const
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
Asterisk operator. Returns a reference to the current iterator item.
QValueListIterator<;T> & QValueListIterator::operator++ ()
Prefix ++ makes the succeeding item current and returns an iterator pointing to the new current item. The iterator cannot check whether it
reached the end of the list. Incrementing the iterator returned by end() causes undefined results.
QValueListIterator<;T> QValueListIterator::operator++ ( int )
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
Postfix ++ makes the succeeding item current and returns an iterator pointing to the new current item. The iterator cannot check whether it
reached the end of the list. Incrementing the iterator returned by end() causes undefined results.
QValueListIterator<;T> & QValueListIterator::operator+= ( int j )
Postfix -- jumps j steps forward in the list. The iterator cannot check whether it reached the end of the list. Jumping past the end()
causes undefined results.
QValueListIterator<;T> & QValueListIterator::operator-- ()
Prefix -- makes the previous item current and returns an iterator pointing to the new current item. The iterator cannot check whether it
reached the beginning of the list. Decrementing the iterator returned by begin() causes undefined results.
QValueListIterator<;T> QValueListIterator::operator-- ( int )
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
Postfix -- makes the previous item current and returns an iterator pointing to the new current item. The iterator cannot check whether it
reached the beginning of the list. Decrementing the iterator returned by begin() causes undefined results.
QValueListIterator<;T> & QValueListIterator::operator-= ( int j )
Postfix -- jumps j steps backward in the list. The iterator cannot check whether it reached the beginning of the list. Jumping past begin()
causes undefined results.
bool QValueListIterator::operator== ( const QValueListIterator<T> & it ) const
Compares this iterator and it and returns TRUE if they point to the same item; otherwise returns FALSE.
SEE ALSO
http://doc.trolltech.com/qvaluelistiterator.html http://www.trolltech.com/faq/tech.html
COPYRIGHT
Copyright 1992-2001 Trolltech AS, http://www.trolltech.com. See the license file included in the distribution for a complete license
statement.
AUTHOR
Generated automatically from the source code.
BUGS
If you find a bug in Qt, please report it as described in http://doc.trolltech.com/bughowto.html. Good bug reports help us to help you.
Thank you.
The definitive Qt documentation is provided in HTML format; it is located at $QTDIR/doc/html and can be read using Qt Assistant or with a
web browser. This man page is provided as a convenience for those users who prefer man pages, although this format is not officially
supported by Trolltech.
If you find errors in this manual page, please report them to qt-bugs@trolltech.com. Please include the name of the manual page
(qvaluelistiterator.3qt) and the Qt version (3.1.1).
Trolltech AS 9 December 2002 QValueListIterator(3qt)