The QIntDict class is a template class that provides a dictionary based on long keys.
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Detailed Description
The QIntDict class is a template class that provides a dictionary based on long keys.
QMap is an STL-compatible alternative to this class.
QIntDict is implemented as a template class. Define a template
instance QIntDict<X> to create a dictionary that operates on
pointers to X (X*).
A dictionary is a collection of key-value pairs. The key is an long used for insertion, removal and lookup. The value is a
pointer. Dictionaries provide very fast insertion and lookup.
Example:
QIntDict<QLineEdit> fields; // long int keys, QLineEdit* values
for ( int i = 0; i < 3; i++ )
fields.insert( i, new QLineEdit( this ) );
fields[0]->setText( "Homer" );
fields[1]->setText( "Simpson" );
fields[2]->setText( "45" );
QIntDictIterator<QLineEdit> it( fields );
for ( ; it.current(); ++it )
cout << it.currentKey() << ": " << it.current()->text() << endl;
for ( int i = 0; i < 3; i++ )
cout << fields[i]->text() << " "; // Prints "Homer Simpson 45"
cout << endl;
fields.remove( 1 ); // Does not delete the line edit
for ( int i = 0; i < 3; i++ )
if ( fields[i] )
cout << fields[i]->text() << " "; // Prints "Homer 45"
See QDict for full details, including the choice of dictionary
size, and how deletions are handled.
See also QIntDictIterator, QDict, QAsciiDict, QPtrDict, Collection Classes, Collection Classes and Non-GUI Classes.
Member Function Documentation
QIntDict::QIntDict ( int size = 17 )
Constructs a dictionary using an internal hash array of size size.
Setting size to a suitably large prime number (equal to or
greater than the expected number of entries) makes the hash
distribution better which leads to faster lookup.
QIntDict::QIntDict ( const QIntDict<type> & dict )
Constructs a copy of dict.
Each item in dict is inserted into this dictionary. Only the
pointers are copied (shallow copy).
QIntDict::~QIntDict ()
Removes all items from the dictionary and destroys it.
All iterators that access this dictionary will be reset.
See also setAutoDelete().
bool QPtrCollection::autoDelete () const
Returns the setting of the auto-delete option. The default is FALSE.
See also setAutoDelete().
void QIntDict::clear () [virtual]
Removes all items from the dictionary.
The removed items are deleted if auto-deletion is enabled.
All dictionary iterators that access this dictionary will be reset.
See also remove(), take() and setAutoDelete().
Reimplemented from QPtrCollection.
uint QIntDict::count () const [virtual]
Returns the number of items in the dictionary.
See also isEmpty().
Reimplemented from QPtrCollection.
type * QIntDict::find ( long key ) const
Returns the item associated with key, or 0 if the key does not
exist in the dictionary.
If there are two or more items with equal keys, then the most
recently inserted item will be found.
Equivalent to operator[].
Warning: Your application will crash if you call find() on an
empty dictionary; you can check with isEmpty() or count(). We
don't perform this check for efficiency reasons.
See also operator[]().
Example: table/bigtable/main.cpp.
void QIntDict::insert ( long key, const type * item )
Insert item item into the dictionary using key key.
The key does not have to be unique. If multiple items are inserted
with the same key, only the most recent item will be accessible.
item may not be 0.
See also replace().
Example: scribble/scribble.cpp.
bool QIntDict::isEmpty () const
Returns TRUE if the dictionary is empty; otherwise returns FALSE.
See also count().
QIntDict<type> & QIntDict::operator= ( const QIntDict<type> & dict )
Assigns dict to this dictionary and returns a reference to this
dictionary.
This dictionary is first cleared and then each item in dict is
inserted into this dictionary. Only the pointers are copied
(shallow copy), unless newItem() has been reimplemented.
type * QIntDict::operator[] ( long key ) const
Returns the item associated with key, or 0 if the key does not
exist in the dictionary.
If there are two or more items with equal keys, then the most
recently inserted item will be found.
Equivalent to the find() function.
Warning: Your application will crash if you call find() on an
empty dictionary; you can check with isEmpty() or count(). We
don't perform this check for efficiency reasons.
See also find().
Reads a dictionary item from the stream s and returns a
reference to the stream.
The default implementation sets item to 0.
See also write().
bool QIntDict::remove ( long key )
Removes the item associated with key from the dictionary.
Returns TRUE if successful, i.e. if the key is in the
dictionary; otherwise returns FALSE.
If there are two or more items with equal keys, then the most
recently inserted item will be removed.
The removed item is deleted if auto-deletion is enabled.
All dictionary iterators that refer to the removed item will be
set to point to the next item in the dictionary's traversal
order.
See also take(), clear() and setAutoDelete().
Example: table/bigtable/main.cpp.
void QIntDict::replace ( long key, const type * item )
If the dictionary has key key, this key's item is replaced with
item. If the dictionary doesn't contain key key, item is
inserted into the dictionary using key key.
item may not be 0.
Equivalent to:
QIntDict<char> dict;
// ...
if ( dict.find(key) )
dict.remove( key );
dict.insert( key, item );
If there are two or more items with equal keys, then the most
recently inserted item will be replaced.
See also insert().
Example: table/bigtable/main.cpp.
void QIntDict::resize ( uint newsize )
Changes the size of the hashtable to newsize. The contents of
the dictionary are preserved, but all iterators on the dictionary
become invalid.
void QPtrCollection::setAutoDelete ( bool enable )
Sets the collection to auto-delete its contents if enable is
TRUE and to never delete them if enable is FALSE.
If auto-deleting is turned on, all the items in a collection are
deleted when the collection itself is deleted. This is convenient
if the collection has the only pointer to the items.
The default setting is FALSE, for safety. If you turn it on, be
careful about copying the collection - you might find yourself
with two collections deleting the same items.
Note that the auto-delete setting may also affect other functions
in subclasses. For example, a subclass that has a remove()
function will remove the item from its data structure, and if
auto-delete is enabled, will also delete the item.
See also autoDelete().
Examples: grapher/grapher.cpp, scribble/scribble.cpp and table/bigtable/main.cpp.
uint QIntDict::size () const
Returns the size of the internal hash array (as specified in the
constructor).
See also count().
void QIntDict::statistics () const
Debugging-only function that prints out the dictionary
distribution using qDebug().
type * QIntDict::take ( long key )
Takes the item associated with key out of the dictionary
without deleting it (even if auto-deletion is enabled).
If there are two or more items with equal keys, then the most
recently inserted item will be taken.
Returns a pointer to the item taken out, or 0 if the key does not
exist in the dictionary.
All dictionary iterators that refer to the taken item will be set
to point to the next item in the dictionary's traversing order.
See also remove(), clear() and setAutoDelete().
Writes a dictionary item to the stream s and returns a
reference to the stream.
See also read().
This file is part of the Qt toolkit.
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