QPtrDictIterator Class Reference

The QPtrDictIterator class provides an iterator for QPtrDict collections. More...

#include <qptrdict.h>

Public Members

QPtrDictIterator ( const QPtrDict<type> & dict )
~QPtrDictIterator ()
uint count () const
bool isEmpty () const
type * toFirst ()
operator type * () const
type * current () const
void * currentKey () const
type * operator() ()
type * operator++ ()
type * operator+= ( uint jump )

Detailed Description

The QPtrDictIterator class provides an iterator for QPtrDict collections.

QPtrDictIterator is implemented as a template class. Define a template instance QPtrDictIterator<X> to create a dictionary iterator that operates on QPtrDict<X> (dictionary of X*).

Example:

    QPtrDict<char> fields;

    QLineEdit *le1 = new QLineEdit( this );
    le1->setText( "Simpson" );
    QLineEdit *le2 = new QLineEdit( this );
    le2->setText( "Homer" );
    QLineEdit *le3 = new QLineEdit( this );
    le3->setText( "45" );

    fields.insert( le1, "Surname" );
    fields.insert( le2, "Forename" );
    fields.insert( le3, "Age" );

    QPtrDictIterator<char> it( fields );
    for( ; it.current(); ++it ) {
        QLineEdit *le = (QLineEdit)it.currentKey();
        cout << it.current() << ": " << le->text() << endl;
    }
    cout << endl;

    // Output (random order):
    //  Forename: Homer
    //  Age: 45
    //  Surname: Simpson

In the example we insert some line edits into a dictionary, associating a string with each. We then iterate over the dictionary printing the associated strings.

Multiple iterators may independently traverse the same dictionary. A QPtrDict knows about all the iterators that are operating on the dictionary. When an item is removed from the dictionary, QPtrDict updates all iterators that refer the removed item to point to the next item in the traversing order.

See also QPtrDict, Collection Classes, and Non-GUI Classes.

Member Function Documentation

QPtrDictIterator::QPtrDictIterator ( const QPtrDict<type> & dict )

Constructs an iterator for dict. The current iterator item is set to point on the first item in the dict.

QPtrDictIterator::~QPtrDictIterator ()

Destroys the iterator.

uint QPtrDictIterator::count () const

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

type * QPtrDictIterator::current () const

Returns a pointer to the current iterator item's value.

void * QPtrDictIterator::currentKey () const

Returns the current iterator item's key.

bool QPtrDictIterator::isEmpty () const

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

QPtrDictIterator::operator type * () const

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

type * QPtrDictIterator::operator() ()

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

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

type * QPtrDictIterator::operator++ ()

Prefix ++ makes the succeeding item current and returns the new current item.

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

type * QPtrDictIterator::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 0 and returns 0.

type * QPtrDictIterator::toFirst ()

Sets the current iterator item to point to the first item in the dictionary and returns a pointer to the item. If the dictionary is empty, it sets the current item to 0 and returns 0.

Trademarks

Qt 3.3.8