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Qt 4.8
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Qt 4.8
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The QHash::const_iterator class provides an STL-style const iterator for QHash and QMultiHash. More...
#include <qhash.h>
Public Types | |
| typedef qptrdiff | difference_type |
| typedef std::bidirectional_iterator_tag | iterator_category |
| typedef const T * | pointer |
| typedef const T & | reference |
| typedef T | value_type |
Public Functions | |
| const_iterator () | |
| Constructs an uninitialized iterator. More... | |
| const_iterator (void *node) | |
| const_iterator (const iterator &o) | |
| Constructs a copy of other. More... | |
| const Key & | key () const |
| Returns the current item's key. More... | |
| operator Node * () const | |
| bool | operator!= (const const_iterator &o) const |
| Returns true if other points to a different item than this iterator; otherwise returns false. More... | |
| const T & | operator* () const |
| Returns the current item's value. More... | |
| const_iterator | operator+ (int j) const |
| Returns an iterator to the item at j positions forward from this iterator. More... | |
| const_iterator & | operator++ () |
The prefix ++ operator (++i) advances the iterator to the next item in the hash and returns an iterator to the new current item. More... | |
| const_iterator | operator++ (int) |
The postfix ++ operator (i++) advances the iterator to the next item in the hash and returns an iterator to the previously current item. More... | |
| const_iterator & | operator+= (int j) |
| Advances the iterator by j items. More... | |
| const_iterator | operator- (int j) const |
| Returns an iterator to the item at j positions backward from this iterator. More... | |
| const_iterator & | operator-- () |
The prefix – operator (–i) makes the preceding item current and returns an iterator pointing to the new current item. More... | |
| const_iterator | operator-- (int) |
The postfix – operator (i–) makes the preceding item current and returns an iterator pointing to the previously current item. More... | |
| const_iterator & | operator-= (int j) |
| Makes the iterator go back by j items. More... | |
| const T * | operator-> () const |
| Returns a pointer to the current item's value. More... | |
| bool | operator== (const const_iterator &o) const |
| Returns true if other points to the same item as this iterator; otherwise returns false. More... | |
| const T & | value () const |
| Returns the current item's value. More... | |
Private Functions | |
| operator bool () const | |
Properties | |
| QHashData::Node * | i |
Friends | |
| class | iterator |
The QHash::const_iterator class provides an STL-style const iterator for QHash and QMultiHash.
QHash features both STL-style iterators and Java-style iterators. The STL-style iterators are more low-level and more cumbersome to use; on the other hand, they are slightly faster and, for developers who already know STL, have the advantage of familiarity.
QHash<Key, T>::const_iterator allows you to iterate over a QHash (or a QMultiHash). If you want to modify the QHash as you iterate over it, you must use QHash::iterator instead. It is generally good practice to use QHash::const_iterator on a non-const QHash as well, unless you need to change the QHash through the iterator. Const iterators are slightly faster, and can improve code readability.
The default QHash::const_iterator constructor creates an uninitialized iterator. You must initialize it using a QHash function like QHash::constBegin(), QHash::constEnd(), or QHash::find() before you can start iterating. Here's a typical loop that prints all the (key, value) pairs stored in a hash:
Unlike QMap, which orders its items by key, QHash stores its items in an arbitrary order. The only guarantee is that items that share the same key (because they were inserted using QHash::insertMulti()) will appear consecutively, from the most recently to the least recently inserted value.
Multiple iterators can be used on the same hash. However, be aware that any modification performed directly on the QHash has the potential of dramatically changing the order in which the items are stored in the hash, as they might cause QHash to rehash its internal data structure. If you need to keep iterators over a long period of time, we recommend that you use QMap rather than QHash.
| QHash< Key, T >::const_iterator::difference_type |
| QHash< Key, T >::const_iterator::iterator_category |
| QHash< Key, T >::const_iterator::pointer |
| QHash< Key, T >::const_iterator::reference |
| QHash< Key, T >::const_iterator::value_type |
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inline |
Constructs an uninitialized iterator.
Functions like key(), value(), and operator++() must not be called on an uninitialized iterator. Use operator=() to assign a value to it before using it.
Definition at line 409 of file qhash.h.
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inlineexplicit |
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inline |
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inline |
Returns the current item's key.
Definition at line 419 of file qhash.h.
Referenced by QStateMachinePrivate::cancelAllDelayedEvents(), QMultiHash< const QGLContext *, GLProgram >::count(), QMultiHash< const QGLContext *, GLProgram >::find(), QMainWindowLayout::fixSizeInUnifiedToolbar(), QApplication::font(), operator<<(), QApplication::palette(), QDeclarativeMetaType::qmlType(), QStateMachinePrivate::restorablesToPropertyList(), QAxScriptManager::scriptNames(), QCss::StyleSelector::styleRulesForNode(), QFont::substitutions(), QGraphicsScenePrivate::touchEventHandler(), QApplicationPrivate::translateRawTouchEvent(), and QAxScriptManager::updateScript().
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Returns true if other points to a different item than this iterator; otherwise returns false.
Definition at line 424 of file qhash.h.
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inline |
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inline |
Returns an iterator to the item at j positions forward from this iterator.
(If j is negative, the iterator goes backward.)
This operation can be slow for large j values.
Definition at line 444 of file qhash.h.
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inline |
The prefix ++ operator (++i) advances the iterator to the next item in the hash and returns an iterator to the new current item.
Calling this function on QHash::end() leads to undefined results.
Definition at line 426 of file qhash.h.
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inline |
The postfix ++ operator (i++) advances the iterator to the next item in the hash and returns an iterator to the previously current item.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Definition at line 430 of file qhash.h.
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inline |
Advances the iterator by j items.
(If j is negative, the iterator goes backward.)
This operation can be slow for large j values.
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inline |
Returns an iterator to the item at j positions backward from this iterator.
(If j is negative, the iterator goes forward.)
This operation can be slow for large j values.
Definition at line 446 of file qhash.h.
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inline |
The prefix – operator (–i) makes the preceding item current and returns an iterator pointing to the new current item.
Calling this function on QHash::begin() leads to undefined results.
Definition at line 435 of file qhash.h.
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inline |
The postfix – operator (i–) makes the preceding item current and returns an iterator pointing to the previously current item.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Definition at line 439 of file qhash.h.
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Makes the iterator go back by j items.
(If j is negative, the iterator goes forward.)
This operation can be slow for large j values.
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Returns true if other points to the same item as this iterator; otherwise returns false.
Definition at line 423 of file qhash.h.
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Returns the current item's value.
Definition at line 420 of file qhash.h.
Referenced by QGLGlyphCache::cacheGlyphs(), QStateMachinePrivate::cancelAllDelayedEvents(), QGLGlyphCache::cleanCache(), cleanup_cmaps(), QBearerEngine::configurationsInUse(), QMultiHash< const QGLContext *, GLProgram >::count(), QMultiHash< const QGLContext *, GLProgram >::find(), QMainWindowLayout::fixSizeInUnifiedToolbar(), QDeclarativeJS::Ecma::RegExp::flagFromChar(), QApplication::font(), QAxScriptManager::functions(), QSortFilterProxyModelPrivate::index_to_iterator(), QScriptDebuggerCodeWidget::invalidateExecutionLineNumbers(), QGLGlyphCache::lookup(), QScriptEnginePrivate::mark(), operator<<(), QApplication::palette(), QScriptEnginePrivate::qobjectData(), qt_gl_choose_cmap(), qt_transparent_pixel(), QEventDispatcherMac::registeredTimers(), QStyleSheetStyle::renderRule(), QStateMachinePrivate::restorablesToPropertyList(), QFileSystemModelPrivate::QFileSystemNode::retranslateStrings(), QDomElementPrivate::save(), QAxScriptManager::scriptForFunction(), QDialogButtonBox::setStandardButtons(), QFileSystemModelPrivate::sortChildren(), QStyleSheetStyle::styleRules(), QCss::StyleSelector::styleRulesForNode(), QApplicationPrivate::translateRawTouchEvent(), QFileSystemModelPrivate::QFileSystemNode::updateIcon(), QFileSystemModelPrivate::QFileSystemNode::~QFileSystemNode(), and QScriptEnginePrivate::~QScriptEnginePrivate().
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Definition at line 398 of file qhash.h.
Referenced by QHash< Key, T >::iterator::operator!=(), QHash< Key, T >::const_iterator::operator!=(), QHash< Key, T >::iterator::operator==(), and QHash< Key, T >::const_iterator::operator==().