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6	<title>QDict Class</title>
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32	<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QDict Class Reference</h1>
33
34	<p>The QDict class is a template class that provides a
35	dictionary based on QString keys.
36	<a href="#details">More...</a>
37	<p><tt>#include <<a href="qdict-h.html">qdict.h</a>></tt>
38	<p>Inherits <a href="qptrcollection.html">QPtrCollection</a>.
39	<p><a href="qdict-members.html">List of all member functions.</a>
40	<h2>Public Members</h2>
41	<ul>
42	<li class=fn><a href="#QDict"><b>QDict</b></a> ( int size = 17, bool caseSensitive = TRUE )</li>
43	<li class=fn><a href="#QDict-2"><b>QDict</b></a> ( const QDict<type> & dict )</li>
44	<li class=fn><a href="#~QDict"><b>~QDict</b></a> ()</li>
45	<li class=fn>QDict<type> & <a href="#operator-eq"><b>operator=</b></a> ( const QDict<type> & dict )</li>
46	<li class=fn>virtual uint <a href="#count"><b>count</b></a> () const</li>
47	<li class=fn>uint <a href="#size"><b>size</b></a> () const</li>
48	<li class=fn>bool <a href="#isEmpty"><b>isEmpty</b></a> () const</li>
49	<li class=fn>void <a href="#insert"><b>insert</b></a> ( const QString & key, const type * item )</li>
50	<li class=fn>void <a href="#replace"><b>replace</b></a> ( const QString & key, const type * item )</li>
51	<li class=fn>bool <a href="#remove"><b>remove</b></a> ( const QString & key )</li>
52	<li class=fn>type * <a href="#take"><b>take</b></a> ( const QString & key )</li>
53	<li class=fn>type * <a href="#find"><b>find</b></a> ( const QString & key ) const</li>
54	<li class=fn>type * <a href="#operator[]"><b>operator[]</b></a> ( const QString & key ) const</li>
55	<li class=fn>virtual void <a href="#clear"><b>clear</b></a> ()</li>
56	<li class=fn>void <a href="#resize"><b>resize</b></a> ( uint newsize )</li>
57	<li class=fn>void <a href="#statistics"><b>statistics</b></a> () const</li>
58	</ul>
59	<h2>Important Inherited Members</h2>
60	<ul>
61	<li class=fn>bool <a href="#autoDelete"><b>autoDelete</b></a> () const</li>
62	<li class=fn>void <a href="#setAutoDelete"><b>setAutoDelete</b></a> ( bool enable )</li>
63	</ul>
64	<h2>Protected Members</h2>
65	<ul>
66	<li class=fn>virtual QDataStream & <a href="#read"><b>read</b></a> ( QDataStream & s, QPtrCollection::Item & item )</li>
67	<li class=fn>virtual QDataStream & <a href="#write"><b>write</b></a> ( QDataStream & s, QPtrCollection::Item ) const</li>
68	</ul>
69	<hr><a name="details"></a><h2>Detailed Description</h2>
70
71
72	The QDict class is a template class that provides a
73	dictionary based on <a href="qstring.html">QString</a> keys.
74	<p>
75
76
77	<p>
78	<p> <a href="qmap.html">QMap</a> is an STL-compatible alternative to this class.
79	<p> QDict is implemented as a template class. Define a template
80	instance QDict<X> to create a dictionary that operates on
81	pointers to X (X *).
82	<p> A dictionary is a collection of key-value pairs. The key is a
83	QString used for insertion, removal and lookup. The value is a
84	pointer. Dictionaries provide very fast insertion and lookup.
85	<p> If you want to use non-Unicode, plain 8-bit <tt>char*</tt> keys, use the
86	<a href="qasciidict.html">QAsciiDict</a> template. A QDict has the same performance as a
87	QAsciiDict. If you want to have a dictionary that maps QStrings to
88	QStrings use QMap.
89	<p> The <a href="#size">size</a>() of the dictionary is very important. In order to get
90	good performance, you should use a suitably large <a href="primes.html#prime">prime</a> number.
91	Suitable means equal to or larger than the maximum expected number
92	of dictionary items. Size is set in the constructor but may be
93	changed with <a href="#resize">resize</a>().
94	<p> Items are inserted with <a href="#insert">insert</a>(); 0 pointers cannot be inserted.
95	Items are removed with <a href="#remove">remove</a>(). All the items in a dictionary can
96	be removed with <a href="#clear">clear</a>(). The number of items in the dictionary is
97	returned by <a href="#count">count</a>(). If the dictionary contains no items <a href="#isEmpty">isEmpty</a>()
98	returns TRUE. You can change an item's value with <a href="#replace">replace</a>(). Items
99	are looked up with <a href="#operator[]">operator[]</a>(), or with <a href="#find">find</a>() which return a
100	pointer to the value or 0 if the given key does not exist. You can
101	take an item out of the dictionary with <a href="#take">take</a>().
102	<p> Calling <a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>(TRUE) for a dictionary tells it to delete
103	items that are removed. The default behaviour is not to delete
104	items when they are removed.
105	<p> When an item is inserted, the key is converted (hashed) to an
106	integer index into an internal hash array. This makes lookup very
107	fast.
108	<p> Items with equal keys are allowed. When inserting two items with
109	the same key, only the last inserted item will be accessible (last
110	in, first out) until it is removed.
111	<p> The <a href="qdictiterator.html">QDictIterator</a> class can traverse the dictionary, but only in
112	an arbitrary order. Multiple iterators may independently traverse
113	the same dictionary.
114	<p> When inserting an item into a dictionary, only the pointer is
115	copied, not the item itself, i.e. a <a href="shclass.html#shallow-copy">shallow copy</a> is made. It is
116	possible to make the dictionary copy all of the item's data (a
117	<a href="shclass.html#deep-copy">deep copy</a>) when an item is inserted. <a href="#insert">insert</a>() calls the virtual
118	function <a href="qptrcollection.html#newItem">QPtrCollection::newItem</a>() for the item to be inserted.
119	Inherit a dictionary and reimplement <a href="qptrcollection.html#newItem">newItem</a>() if you want deep
120	copies.
121	<p> When removing a dictionary item, the virtual function
122	<a href="qptrcollection.html#deleteItem">QPtrCollection::deleteItem</a>() is called. QDict's default
123	implementation is to delete the item if auto-deletion is enabled.
124	<p> Example #1:
125	<pre>
126	QDict<QLineEdit> fields; // QString keys, QLineEdit* values
127	fields.<a href="#insert">insert</a>( "forename", new <a href="qlineedit.html">QLineEdit</a>( this ) );
128	fields.<a href="#insert">insert</a>( "surname", new <a href="qlineedit.html">QLineEdit</a>( this ) );
129
130	fields["forename"]->setText( "Homer" );
131	fields["surname"]->setText( "Simpson" );
132
133	<a href="qdictiterator.html">QDictIterator</a><QLineEdit> it( fields ); // See QDictIterator
134	for( ; it.<a href="qdictiterator.html#current">current</a>(); ++it )
135	cout << it.<a href="qdictiterator.html#currentKey">currentKey</a>() << ": " << it.<a href="qdictiterator.html#current">current</a>()->text() << endl;
136	cout << endl;
137
138	if ( fields["forename"] && fields["surname"] )
139	cout << fields["forename"]->text() << " "
140	<< fields["surname"]->text() << endl; // Prints "Homer Simpson"
141
142	fields.<a href="#remove">remove</a>( "forename" ); // Does not delete the line edit
143	if ( ! fields["forename"] )
144	cout << "forename is not in the dictionary" << endl;
145	</pre>
146
147	In this example we use a dictionary to keep track of the line
148	edits we're using. We insert each line edit into the dictionary
149	with a unique name and then access the line edits via the
150	dictionary.
151	<p> Example #2:
152	<pre>
153	<a href="qstringlist.html">QStringList</a> styleList = QStyleFactory::styles();
154	styleList.<a href="qstringlist.html#sort">sort</a>();
155	QDict<int> letterDict( 17, FALSE );
156	for ( QStringList::Iterator it = styleList.<a href="qvaluelist.html#begin">begin</a>(); it != styleList.<a href="qvaluelist.html#end">end</a>(); ++it ) {
157	<a href="qstring.html">QString</a> styleName = *it;
158	<a href="qstring.html">QString</a> styleAccel = styleName;
159	if ( letterDict[styleAccel.<a href="qstring.html#left">left</a>(1)] ) {
160	for ( uint i = 0; i < styleAccel.<a href="qstring.html#length">length</a>(); i++ ) {
161	if ( ! letterDict[styleAccel.<a href="qstring.html#mid">mid</a>( i, 1 )] ) {
162	styleAccel = styleAccel.<a href="qstring.html#insert">insert</a>( i, '&' );
163	letterDict.<a href="#insert">insert</a>(styleAccel.<a href="qstring.html#mid">mid</a>( i, 1 ), (const int *)1);
164	break;
165	}
166	}
167	} else {
168	styleAccel = "&" + styleAccel;
169	letterDict.<a href="#insert">insert</a>(styleAccel.<a href="qstring.html#left">left</a>(1), (const int *)1);
170	}
171	(void) new <a href="qaction.html">QAction</a>( styleName, QIconSet(), styleAccel, parent );
172	}
173	</pre>
174
175	In the example we are using the dictionary to provide fast random
176	access to the keys, and we don't care what the values are. The
177	example is used to generate a menu of QStyles, each with a unique
178	accelerator key (or no accelerator if there are no unused letters
179	left).
180	<p> We first obtain the list of available styles, then sort them so
181	that the menu items will be ordered alphabetically. Next we create
182	a dictionary of int pointers. The keys in the dictionary are each
183	one character long, representing letters that have been used for
184	accelerators. We iterate through our list of style names. If the
185	first letter of the style name is in the dictionary, i.e. has been
186	used, we iterate over all the characters in the style name to see
187	if we can find a letter that hasn't been used. If we find an
188	unused letter we put the accelerator ampersand (&) in front of it
189	and add that letter to the dictionary. If we can't find an unused
190	letter the style will simply have no accelerator. If the first
191	letter of the style name is not in the dictionary we use it for
192	the accelerator and add it to the dictionary. Finally we create a
193	<a href="qaction.html">QAction</a> for each style.
194	<p> <p>See also <a href="qdictiterator.html">QDictIterator</a>, <a href="qasciidict.html">QAsciiDict</a>, <a href="qintdict.html">QIntDict</a>, <a href="qptrdict.html">QPtrDict</a>, <a href="collection.html">Collection Classes</a>, and <a href="tools.html">Non-GUI Classes</a>.
195
196	<hr><h2>Member Function Documentation</h2>
197	<h3 class=fn><a name="QDict"></a>QDict::QDict ( int size = 17, bool caseSensitive = TRUE )
198	</h3>
199
200	<p> Constructs a dictionary optimized for less than <em>size</em> entries.
201	<p> We recommend setting <em>size</em> to a suitably large <a href="primes.html#prime">prime</a> number
202	(e.g. a prime that's slightly larger than the expected number of
203	entries). This makes the hash distribution better which will lead
204	to faster lookup.
205	<p> If <em>caseSensitive</em> is TRUE (the default), keys which differ only
206	by case are considered different.
207
208	<h3 class=fn><a name="QDict-2"></a>QDict::QDict ( const <a href="qdict.html">QDict</a><type> & dict )
209	</h3>
210
211	<p> Constructs a copy of <em>dict</em>.
212	<p> Each item in <em>dict</em> is inserted into this dictionary. Only the
213	pointers are copied (shallow copy).
214
215	<h3 class=fn><a name="~QDict"></a>QDict::~QDict ()
216	</h3>
217
218	<p> Removes all items from the dictionary and destroys it. If
219	<a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>() is TRUE, each value is deleted. All iterators that
220	access this dictionary will be reset.
221	<p> <p>See also <a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>().
222
223	<h3 class=fn>bool <a name="autoDelete"></a>QPtrCollection::autoDelete () const
224	</h3>
225
226	<p> Returns the setting of the auto-delete option. The default is FALSE.
227	<p> <p>See also <a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>().
228
229	<h3 class=fn>void <a name="clear"></a>QDict::clear ()<tt> [virtual]</tt>
230	</h3>
231
232	<p> Removes all items from the dictionary.
233	<p> The removed items are deleted if <a href="qptrcollection.html#setAutoDelete">auto-deletion</a> is enabled.
234	<p> All dictionary iterators that operate on the dictionary are reset.
235	<p> <p>See also <a href="#remove">remove</a>(), <a href="#take">take</a>(), and <a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>().
236
237	<p>Reimplemented from <a href="qptrcollection.html#clear">QPtrCollection</a>.
238	<h3 class=fn>uint <a name="count"></a>QDict::count () const<tt> [virtual]</tt>
239	</h3>
240
241	<p> Returns the number of items in the dictionary.
242	<p> <p>See also <a href="#isEmpty">isEmpty</a>().
243
244	<p>Reimplemented from <a href="qptrcollection.html#count">QPtrCollection</a>.
245	<h3 class=fn>type * <a name="find"></a>QDict::find ( const <a href="qstring.html">QString</a> & key ) const
246	</h3>
247
248	<p> Returns the item with key <em>key</em>, or 0 if the key does not exist
249	in the dictionary.
250	<p> If there are two or more items with equal keys, then the most
251	recently inserted item will be found.
252	<p> Equivalent to the [] operator.
253	<p> <p>See also <a href="#operator[]">operator[]</a>().
254
255	<h3 class=fn>void <a name="insert"></a>QDict::insert ( const <a href="qstring.html">QString</a> & key, const type * item )
256	</h3>
257
258	<p> Inserts the key <em>key</em> with value <em>item</em> into the dictionary.
259	<p> Multiple items can have the same key, in which case only the last
260	item will be accessible using <a href="#operator[]">operator[]</a>().
261	<p> <em>item</em> may not be 0.
262	<p> <p>See also <a href="#replace">replace</a>().
263
264	<p>Example: <a href="themes-example.html#x326">themes/themes.cpp</a>.
265	<h3 class=fn>bool <a name="isEmpty"></a>QDict::isEmpty () const
266	</h3>
267
268	<p> Returns TRUE if the dictionary is empty, i.e. <a href="#count">count</a>() == 0;
269	otherwise returns FALSE.
270	<p> <p>See also <a href="#count">count</a>().
271
272	<h3 class=fn><a href="qdict.html">QDict</a><type> & <a name="operator-eq"></a>QDict::operator= ( const <a href="qdict.html">QDict</a><type> & dict )
273	</h3>
274
275	<p> Assigns <em>dict</em> to this dictionary and returns a reference to this
276	dictionary.
277	<p> This dictionary is first cleared, then each item in <em>dict</em> is
278	inserted into this dictionary. Only the pointers are copied
279	(shallow copy), unless <a href="qptrcollection.html#newItem">newItem</a>() has been reimplemented.
280
281	<h3 class=fn>type * <a name="operator[]"></a>QDict::operator[] ( const <a href="qstring.html">QString</a> & key ) const
282	</h3>
283
284	<p> Returns the item with key <em>key</em>, or 0 if the key does not
285	exist in the dictionary.
286	<p> If there are two or more items with equal keys, then the most
287	recently inserted item will be found.
288	<p> Equivalent to the <a href="#find">find</a>() function.
289	<p> <p>See also <a href="#find">find</a>().
290
291	<h3 class=fn><a href="qdatastream.html">QDataStream</a> & <a name="read"></a>QDict::read ( <a href="qdatastream.html">QDataStream</a> & s, <a href="qptrcollection.html#Item">QPtrCollection::Item</a> & item )<tt> [virtual protected]</tt>
292	</h3>
293
294	<p> Reads a dictionary item from the stream <em>s</em> and returns a
295	reference to the stream.
296	<p> The default implementation sets <em>item</em> to 0.
297	<p> <p>See also <a href="#write">write</a>().
298
299	<h3 class=fn>bool <a name="remove"></a>QDict::remove ( const <a href="qstring.html">QString</a> & key )
300	</h3>
301
302	<p> Removes the item with <em>key</em> from the dictionary. Returns TRUE if
303	successful, i.e. if the item is in the dictionary; otherwise
304	returns FALSE.
305	<p> If there are two or more items with equal keys, then the last item
306	that was inserted will be removed.
307	<p> The removed item is deleted if <a href="qptrcollection.html#setAutoDelete">auto-deletion</a> is enabled.
308	<p> All dictionary iterators that refer to the removed item will be
309	set to point to the next item in the dictionary's traversal order.
310	<p> <p>See also <a href="#take">take</a>(), <a href="#clear">clear</a>(), and <a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>().
311
312	<h3 class=fn>void <a name="replace"></a>QDict::replace ( const <a href="qstring.html">QString</a> & key, const type * item )
313	</h3>
314
315	<p> Replaces the value of the key, <em>key</em> with <em>item</em>.
316	<p> If the item does not already exist, it will be inserted.
317	<p> <em>item</em> may not be 0.
318	<p> Equivalent to:
319	<pre>
320	QDict<char> dict;
321	...
322	if ( dict.<a href="#find">find</a>( key ) )
323	dict.<a href="#remove">remove</a>( key );
324	dict.<a href="#insert">insert</a>( key, item );
325	</pre>
326
327	<p> If there are two or more items with equal keys, then the last item
328	that was inserted will be replaced.
329	<p> <p>See also <a href="#insert">insert</a>().
330
331	<h3 class=fn>void <a name="resize"></a>QDict::resize ( uint newsize )
332	</h3>
333
334	<p> Changes the size of the hash table to <em>newsize</em>. The contents of
335	the dictionary are preserved, but all iterators on the dictionary
336	become invalid.
337
338	<h3 class=fn>void <a name="setAutoDelete"></a>QPtrCollection::setAutoDelete ( bool enable )
339	</h3>
340
341	<p> Sets the collection to auto-delete its contents if <em>enable</em> is
342	TRUE and to never delete them if <em>enable</em> is FALSE.
343	<p> If auto-deleting is turned on, all the items in a collection are
344	deleted when the collection itself is deleted. This is convenient
345	if the collection has the only pointer to the items.
346	<p> The default setting is FALSE, for safety. If you turn it on, be
347	careful about copying the collection - you might find yourself
348	with two collections deleting the same items.
349	<p> Note that the auto-delete setting may also affect other functions
350	in subclasses. For example, a subclass that has a <a href="#remove">remove</a>()
351	function will remove the item from its data structure, and if
352	auto-delete is enabled, will also delete the item.
353	<p> <p>See also <a href="qptrcollection.html#autoDelete">autoDelete</a>().
354
355	<p>Examples: <a href="grapher-nsplugin-example.html#x2769">grapher/grapher.cpp</a>, <a href="scribble-example.html#x924">scribble/scribble.cpp</a>, and <a href="bigtable-example.html#x1291">table/bigtable/main.cpp</a>.
356	<h3 class=fn>uint <a name="size"></a>QDict::size () const
357	</h3>
358
359	<p> Returns the size of the internal hash array (as specified in the
360	constructor).
361	<p> <p>See also <a href="#count">count</a>().
362
363	<h3 class=fn>void <a name="statistics"></a>QDict::statistics () const
364	</h3>
365
366	<p> Debugging-only function that prints out the dictionary
367	distribution using <a href="qapplication.html#qDebug">qDebug</a>().
368
369	<h3 class=fn>type * <a name="take"></a>QDict::take ( const <a href="qstring.html">QString</a> & key )
370	</h3>
371
372	<p> Takes the item with <em>key</em> out of the dictionary without deleting
373	it (even if <a href="qptrcollection.html#setAutoDelete">auto-deletion</a> is enabled).
374	<p> If there are two or more items with equal keys, then the last item
375	that was inserted will be taken.
376	<p> Returns a pointer to the item taken out, or 0 if the key does not
377	exist in the dictionary.
378	<p> All dictionary iterators that refer to the taken item will be set
379	to point to the next item in the dictionary traversal order.
380	<p> <p>See also <a href="#remove">remove</a>(), <a href="#clear">clear</a>(), and <a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>().
381
382	<h3 class=fn><a href="qdatastream.html">QDataStream</a> & <a name="write"></a>QDict::write ( <a href="qdatastream.html">QDataStream</a> & s, <a href="qptrcollection.html#Item">QPtrCollection::Item</a> ) const<tt> [virtual protected]</tt>
383	</h3>
384
385	<p> Writes a dictionary item to the stream <em>s</em> and returns a
386	reference to the stream.
387	<p> <p>See also <a href="#read">read</a>().
388
389	<!-- eof -->
390	<hr><p>
391	This file is part of the <a href="index.html">Qt toolkit</a>.
392	Copyright © 1995-2007
393	<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center>
394	<table width=100% cellspacing=0 border=0><tr>
395	<td>Copyright © 2007
396	<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
397	<td align=right><div align=right>Qt 3.3.8</div>
398	</table></div></address></body>
399	</html>

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