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# TQDictIterator Class Reference

The TQDictIterator class provides an iterator for TQDict collections. More...

`#include <ntqdict.h>`

List of all member functions.

## Public Members

- TQDictIterator ( const TQDict<type> & dict )
- ~TQDictIterator ()
- uint count () const
- bool isEmpty () const
- type * toFirst ()
- operator type * () const
- type * current () const
- TQString currentKey () const
- type * operator() ()
- type * operator++ ()

## Detailed Description

The TQDictIterator class provides an iterator for TQDict collections.

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

Example:

        TQDict<TQLineEdit> fields;
        fields.insert( "forename", new TQLineEdit( this ) );
        fields.insert( "surname", new TQLineEdit( this ) );
        fields.insert( "age", new TQLineEdit( this ) );

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

        TQDictIterator<TQLineEdit> 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 TQDict, Collection Classes, and Non-GUI Classes.

## Member Function Documentation

### TQDictIterator::TQDictIterator ( const TQDict<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.

### TQDictIterator::~TQDictIterator ()

Destroys the iterator.

### uint TQDictIterator::count () const

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

See also isEmpty().

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

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

### TQString TQDictIterator::currentKey () const

Returns the current iterator item's key.

### bool TQDictIterator::isEmpty () const

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

See also count().

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

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

### type * TQDictIterator::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 * TQDictIterator::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 * TQDictIterator::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.

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