Qt 4.3: Q3DictIterator Class Reference

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# Q3DictIterator Class Reference
[Qt3Support module]

The Q3DictIterator class provides an iterator for Q3Dict collections. More...

     #include <Q3DictIterator>

This class is part of the Qt 3 support library. It is provided to keep old source code working. We strongly advise against using it in new code. See Porting to Qt 4 for more information.

- List of all members, including inherited members

### Public Functions

- Q3DictIterator ( const Q3Dict<type> & dict )
- ~Q3DictIterator ()
- uint count () const
- type * current () const
- QString currentKey () const
- bool isEmpty () const
- type * toFirst ()
- operator type * () const
- type * operator() ()
- type * operator++ ()

## Detailed Description

The Q3DictIterator class provides an iterator for Q3Dict collections.

Q3DictIterator is implemented as a template class. Define a template instance Q3DictIterator<X> to create a dictionary iterator that operates on Q3Dict<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 Q3Dict knows about all the iterators that are operating on the dictionary. When an item is removed from the dictionary, Q3Dict updates all iterators that are referring to the removed item to point to the next item in the (arbitrary) traversal order.

Example:

     Q3Dict<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" );

     Q3DictIterator<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 Q3Dict.

## Member Function Documentation

### Q3DictIterator::Q3DictIterator ( const Q3Dict<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.

### Q3DictIterator::~Q3DictIterator ()

Destroys the iterator.

### uint Q3DictIterator::count () const

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

See also isEmpty().

### type * Q3DictIterator::current () const

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

### QString Q3DictIterator::currentKey () const

Returns the current iterator item's key.

### bool Q3DictIterator::isEmpty () const

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

See also count().

### type * Q3DictIterator::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.

### Q3DictIterator::operator type * () const

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

### type * Q3DictIterator::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 * Q3DictIterator::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.