QListIterator(3qt)QListIterator(3qt)NAMEQListIterator - Iterator for
#include <qlist.h>
Inherits QGListIterator.
Inherited by QStrListIterator.
Public Members
QListIterator ( const QList<type> & list )
~QListIterator ()
uint count () const
bool isEmpty () const
bool atFirst () const
bool atLast () const
type* toFirst ()
type* toLast ()
operator type* ()const
type* operator* ()
type* current () const
type* operator ()
type* operator++ ()
type* operator+= ( uint jump )
type* operator-- ()
type* operator-= ( uint jump )
QListIterator<type>& operator= ( const QListIterator<type>
& it )
DESCRIPTION
The QListIterator class provides an iterator for QList
collections.
Define a template instance QListIterator<X> to create a
list iterator that operates on QList<X> (list of X*).
Example:
#include <qlist.h>
#include <qstring.h>
#include <stdio.h>
class Employee
{
public:
Employee( const char *name, int salary ) { n=name; s=salary; }
const char *name() const { return n; }
int salary() const { return s; }
private:
QString n;
int s;
};
void main()
{
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QList<Employee> list; // list of pointers to Employee
list.setAutoDelete( TRUE ); // delete items when they are removed
list.append( new Employee("Bill", 50000) );
list.append( new Employee("Steve",80000) );
list.append( new Employee("Ron", 60000) );
QListIterator<Employee> it(list); // iterator for employee list
for ( ; it.current(); ++it ) {
Employee *emp = it.current();
printf( "%s earns %d\n", emp->name().latin1(), emp->salary() );
}
}
Program output:
Bill earns 50000
Steve earns 80000
Ron earns 60000
Although QList has member functions to traverse the doubly
linked list structure, using a list iterator is a much
more robust way of traversing the list, because multiple
list iterators can operate on the same list, independent
of each other and independent of the QList's current item.
An iterator has its own current list item and can get the
next and previous list items. It can only traverse the
list, never modify it.
A QList knows about all list iterators that are operating
on the list. When an item is removed from the list, the
list update all iterators that are pointing the removed
item to point to the new current list item.
Example:
#include <qlist.h>
#include <qstring.h>
#include <stdio.h>
class Employee
{
... // same as above
};
void main()
{
QList<Employee> list; // list of pointers to Employee
list.setAutoDelete( TRUE ); // delete items when they are removed
list.append( new Employee("Bill", 50000) );
list.append( new Employee("Steve",80000) );
list.append( new Employee("Ron", 60000) );
QListIterator<Employee> it(list);
list.at( 1 ); // current list item: "Steve"
it.toLast(); // it: "Ron"
--it; // it: "Steve"
// Now, both the list and the iterator are referring the same item
list.remove();
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printf( "%s\n", it.current()->name().latin1() );
}
Program output:
Ron
See also QList and collection classes
Examples: dirview/main.cpp
MEMBER FUNCTION DOCUMENTATIONQListIterator::QListIterator ( const QList<;type> & list )
Constructs an iterator for list. The current iterator item
is set to point on the first item in the list.
QListIterator::~QListIterator ()
Destroys the iterator.
QListIterator::operator type * () const
Cast operator. Returns a pointer to the current iterator
item. Same as current().
bool QListIterator::atFirst () const
Returns TRUE if the current iterator item is the first
list item, otherwise FALSE.
See also toFirst() and atLast().
bool QListIterator::atLast () const
Returns TRUE if the current iterator item is the last list
item, otherwise FALSE.
See also toLast() and atFirst().
uint QListIterator::count () const
Returns the number of items in the list this iterator
operates on.
See also isEmpty().
type * QListIterator::current () const
Returns a pointer to the current iterator item.
bool QListIterator::isEmpty () const
Returns TRUE if the list is empty, i.e. count() == 0,
otherwise FALSE.
See also count().
type * QListIterator::operator() ()
Makes the succeeding item current and returns the original
current item.
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If the current iterator item was the last item in the list
or if it was null, null is returned.
type * QListIterator::operator* ()
Asterix operator. Returns a pointer to the current
iterator item. Same as current().
type * QListIterator::operator++ ()
Prefix ++ makes the succeeding item current and returns
the new current item.
If the current iterator item was the last item in the list
or if it was null, null is returned.
type * QListIterator::operator+= ( uint jump )
Sets the current item to the item jump positions after the
current item, and returns a pointer to that item.
If that item is beyond the last item or if the dictionary
is empty, it sets the current item to null and returns
null.
type * QListIterator::operator-- ()
Prefix -- makes the preceding item current and returns the
new current item.
If the current iterator item was the first item in the
list or if it was null, null is returned.
type * QListIterator::operator-= ( uint jump )
Returns the item jump positions before the current item,
or null if it is beyond the first item. Makes this the
current item.
QListIterator<;type>& QListIterator::operator= ( const
QListIterator<type> & it )
Assignment. Makes a copy of the iterator it and returns a
reference to this iterator.
type * QListIterator::toFirst ()
Sets the current iterator item to point to the first list
item and returns a pointer to the item. Sets the current
item to null and returns null if the list is empty.
See also toLast() and atFirst().
type * QListIterator::toLast ()
Sets the current iterator item to point to the last list
item and returns a pointer to the item. Sets the current
item to null and returns null if the list is empty.
See also toFirst() and atLast().
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QListIterator(3qt)QListIterator(3qt)SEE ALSO
http://doc.trolltech.com/qlistiterator.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
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http://doc.trolltech.com/bughowto.html. Good bug reports
make our job much simpler. Thank you.
In case of content or formattting problems with this
manual page, please report them to qt-bugs@trolltech.com.
Please include the name of the manual page
(qlistiterator.3qt) and the Qt version (2.3.1).
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