Contents

• Public Functions
• Detailed Description

Detailed Description

TheQ3PtrListIterator class provides an iterator forQ3PtrList collections.

Define a template instanceQ3PtrListIterator<X> to create a list iterator that operates onQ3PtrList<X> (list of X*).

The following example is similar to the example in theQ3PtrList class documentation, but it usesQ3PtrListIterator. The class Employee is defined there.

Q3PtrList<Employee> list;list.append(new Employee("John","Doe",50000) );list.append(new Employee("Jane","Williams",80000) );list.append(new Employee("Tom","Jones",60000) );Q3PtrListIterator<Employee> it( list );Employee*employee;while ( (employee= it.current())!=0 ) {++it;    cout<< employee->surname().latin1()<<", "<<            employee->forename().latin1()<<" earns "<<            employee->salary()<< endl;}

The output is

Doe, John earns50000Williams, Jane earns80000Jones, Tom earns60000

Using a list iterator is a more robust way of traversing the list than using theQ3PtrList member functionsfirst(),next(),current(), etc., as many iterators can traverse the same list independently.

An iterator has its own current list item and can get the next and previous list items. It doesn't modify the list in any way.

When an item is removed from the list, all iterators that point to that item are updated to point toQ3PtrList::current() instead to avoid dangling references.

Member Function Documentation

Q3PtrListIterator::Q3PtrListIterator(constQ3PtrList<type> & list)

Constructs an iterator forlist. The current iterator item is set to point on the first item in thelist.

Q3PtrListIterator::~Q3PtrListIterator()

Destroys the iterator.

bool Q3PtrListIterator::atFirst() const

Returns TRUE if the current iterator item is the first list item; otherwise returns FALSE.

See alsotoFirst() andatLast().

bool Q3PtrListIterator::atLast() const

Returns TRUE if the current iterator item is the last list item; otherwise returns FALSE.

See alsotoLast() andatFirst().

uint Q3PtrListIterator::count() const

Returns the number of items in the list this iterator operates on.

See alsoisEmpty().

type * Q3PtrListIterator::current() const

Returns a pointer to the current iterator item. If the iterator is positioned before the first item in the list or after the last item in the list, 0 is returned.

bool Q3PtrListIterator::isEmpty() const

Returns TRUE if the list is empty; otherwise returns FALSE.

See alsocount().

type * Q3PtrListIterator::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 0 and returns 0 if the list is empty.

See alsotoLast() andatFirst().

type * Q3PtrListIterator::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 0 and returns 0 if the list is empty.

See alsotoFirst() andatLast().

Q3PtrListIterator::operator type *() const

Cast operator. Returns a pointer to the current iterator item. Same ascurrent().

type * Q3PtrListIterator::operator()()

Makes the succeeding item current and returns the original current item.

If the current iterator item was the last item in the list or if it was 0, 0 is returned.

type * Q3PtrListIterator::operator*()

Asterisk operator. Returns a pointer to the current iterator item. Same ascurrent().

type * Q3PtrListIterator::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 0, 0 is returned.

type * Q3PtrListIterator::operator+=(uint jump)

Sets the current item to the itemjump positions after the current item and returns a pointer to that item.

If that item is beyond the last item or if the list is empty, it sets the current item to 0 and returns 0

type * Q3PtrListIterator::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 0, 0 is returned.

type * Q3PtrListIterator::operator-=(uint jump)

Returns the itemjump positions before the current item or 0 if it is beyond the first item. Makes this the current item.

Q3PtrListIterator<type> & Q3PtrListIterator::operator=(constQ3PtrListIterator<type> & it)

Assignment. Makes a copy of the iteratorit and returns a reference to this iterator.