QDictIterator Class

Qt 3.0.5

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QDictIterator Class Reference

The QDictIterator class provides an iterator for QDict collections. More...

#include <qdict.h>

List of all member functions.

Public Members

QDictIterator ( const QDict<type> & dict )
~QDictIterator ()
uint count () const
bool isEmpty () const
type * toFirst ()
operator type * () const
type * current () const
QString currentKey () const
type * operator() ()
type * operator++ ()

Detailed Description

The QDictIterator class provides an iterator for QDict collections.

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

The traversal order is arbitrary; when we speak of the "first", "last" and "next" item we are talking in terms of this arbitrary order.

Multiple iterators may independently traverse the same dictionary. A QDict knows about all iterators that are operating on the dictionary. When an item is removed from the dictionary, QDict update all iterators that are referring to the removed item to point to the next item in the traversal order.

Example:

    QDict<QLineEdit> fields;
    fields.insert( "forename", new QLineEdit( this ) );
    fields.insert( "surname", new QLineEdit( this ) );
    fields.insert( "age", new QLineEdit( this ) );

    fields["forename"]->setText( "Homer" );
    fields["surname"]->setText( "Simpson" );
    fields["age"]->setText( "45" );

    QDictIterator<QLineEdit> it( fields );
    for( ; it.current(); ++it )
        cout << it.currentKey() << ": " << it.current()->text() << endl;
    cout << endl;

    // Output (random order):
    //  age: 45
    //  surname: Simpson
    //  forename: Homer

In the example we insert some pointers to line edits into a dictionary, then iterate over the dictionary printing the strings associated with the line edits.

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

Member Function Documentation

QDictIterator::QDictIterator ( const QDict<type> & dict )

Constructs an iterator for dict. The current iterator item is set to point to the first item in the dictionary, dict. First in this context means first in the arbitrary traversal order.

QDictIterator::~QDictIterator ()

Destroys the iterator.

uint QDictIterator::count () const

Returns the number of items in the dictionary over which the iterator is operating.

type * QDictIterator::current () const

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

QString QDictIterator::currentKey () const

Returns the current iterator item's key.

bool QDictIterator::isEmpty () const

Returns TRUE if the dictionary is empty, i.e. count() == 0; otherwise returns FALSE.

QDictIterator::operator type * () const

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

type * QDictIterator::operator() ()

Makes the next 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 * QDictIterator::operator++ ()

Prefix ++ makes the next 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 * QDictIterator::toFirst ()

Resets the iterator, making the first item the first current item. First in this context means first in the arbitrary traversal order. Returns a pointer to this item.

If the dictionary is empty it sets the current item to 0 and returns 0.

Trademarks

Qt version 3.0.5

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