The QMultiMap class is a convenience QMap 子类提供多值映射。 更多...
| 头： | #include <QMultiMap> |
| qmake: | QT += core |
| 继承： | QMap |
注意： 此类的所有函数 可重入 .
| QMultiMap () | |
| QMultiMap (std::initializer_list<std::pair<Key, T> > list ) | |
| QMultiMap (const QMap<Key, T> & other ) | |
| QMultiMap (QMap<Key, T> && other ) | |
| typename QMap<Key, T>::const_iterator | constFind (const Key & key , const T & value ) const |
| bool | contains (const Key & key , const T & value ) const |
| int | count (const Key & key , const T & value ) const |
| typename QMap<Key, T>::iterator | find (const Key & key , const T & value ) |
| typename QMap<Key, T>::const_iterator | find (const Key & key , const T & value ) const |
| typename QMap<Key, T>::iterator | insert (const Key & key , const T & value ) |
| typename QMap<Key, T>::iterator | insert (typename QMap<Key, T>::const_iterator pos , const Key & key , const T & value ) |
| int | remove (const Key & key , const T & value ) |
| typename QMap<Key, T>::iterator | replace (const Key & key , const T & value ) |
| void | swap (QMultiMap<Key, T> & other ) |
| QMultiMap<K, V> | operator+ (const QMultiMap<K, V> & other ) const |
| QMultiMap<K, V> & | operator+= (const QMultiMap<K, V> & other ) |
The QMultiMap class is a convenience QMap 子类提供多值映射。
QMultiMap <Key, T> 是一种 Qt 一般 容器类 . It inherits QMap and extends it with a few convenience functions that make it more suitable than QMap for storing multi-valued maps. A multi-valued map is a map that allows multiple values with the same key; QMap normally doesn't allow that, unless you call QMap::insertMulti ().
因为 QMultiMap 继承 QMap , all of QMap 's functionality also applies to QMultiMap . For example, you can use isEmpty () to test whether the map is empty, and you can traverse a QMultiMap 使用 QMap 的迭代器类 (例如： QMapIterator ). But in addition, it provides an insert () function that corresponds to QMap::insertMulti (), and a replace () function that corresponds to QMap::insert (). It also provides convenient operator+() and operator+=().
范例：
QMultiMap<QString, int> map1, map2, map3; map1.insert("plenty", 100); map1.insert("plenty", 2000); // map1.size() == 2 map2.insert("plenty", 5000); // map2.size() == 1 map3 = map1 + map2; // map3.size() == 3
不像 QMap , QMultiMap provides no operator[]. Use value () 或 replace () if you want to access the most recently inserted item with a certain key.
If you want to retrieve all the values for a single key, you can use values(const Key &key), which returns a QList <T>:
QList<int> values = map.values("plenty"); for (int i = 0; i < values.size(); ++i) cout << values.at(i) << endl;
The items that share the same key are available from most recently to least recently inserted.
If you prefer the STL-style iterators, you can call find () to get the iterator for the first item with a key and iterate from there:
QMultiMap<QString, int>::iterator i = map.find("plenty"); while (i != map.end() && i.key() == "plenty") { cout << i.value() << endl; ++i; }
QMultiMap 's key and value data types must be 可赋值数据类型 . This covers most data types you are likely to encounter, but the compiler won't let you, for example, store a QWidget 作为值；取而代之，存储 QWidget *. In addition, QMultiMap 's key type must provide operator<(). See the QMap 文档编制了解细节。
另请参阅 QMap , QMapIterator , QMutableMapIterator ，和 QMultiHash .
Constructs an empty map.
Constructs a multi-map with a copy of each of the elements in the initializer list list .
This function is only available if the program is being compiled in C++11 mode.
该函数在 Qt 5.1 引入。
构造副本为 other (which can be a QMap 或 QMultiMap ).
另请参阅 operator= ().
Default constructs an instance of QMultiMap.
Returns an iterator pointing to the item with key key and the value value in the map.
If the map contains no such item, the function returns constEnd ().
该函数在 Qt 4.3 引入。
另请参阅 QMap::constFind ().
返回
true
if the map contains an item with key
key
and value
value
；否则返回
false
.
该函数在 Qt 4.3 引入。
另请参阅 QMap::contains ().
Returns the number of items with key key and value value .
该函数在 Qt 4.3 引入。
另请参阅 QMap::count ().
Returns an iterator pointing to the item with key key and value value in the map.
If the map contains no such item, the function returns end ().
If the map contains multiple items with key key , this function returns an iterator that points to the most recently inserted value.
该函数在 Qt 4.3 引入。
另请参阅 QMap::find ().
这是重载函数。
Returns a const iterator pointing to the item with the given key and value in the map.
If the map contains no such item, the function returns end ().
If the map contains multiple items with the specified key , this function returns a const iterator that points to the most recently inserted value.
该函数在 Qt 4.3 引入。
另请参阅 QMap::find ().
Inserts a new item with the key key 和值 value .
If there is already an item with the same key in the map, this function will simply create a new one. (This behavior is different from replace (), which overwrites the value of an existing item.)
另请参阅 replace ().
Inserts a new item with the key key and value value and with hint pos suggesting where to do the insert.
若 constBegin () is used as hint it indicates that the key is less than any key in the map while constEnd () suggests that the key is larger than any key in the map. Otherwise the hint should meet the condition ( pos - 1). key () < key <= pos. key (). If the hint pos is wrong it is ignored and a regular insert is done.
If there is already an item with the same key in the map, this function will simply create a new one.
注意： Be careful with the hint. Providing an iterator from an older shared instance might crash but there is also a risk that it will silently corrupt both the map and the pos map.
该函数在 Qt 5.1 引入。
Removes all the items that have the key key and the value value from the map. Returns the number of items removed.
该函数在 Qt 4.3 引入。
另请参阅 QMap::remove ().
Inserts a new item with the key key 和值 value .
If there is already an item with the key key , that item's value is replaced with value .
If there are multiple items with the key key , the most recently inserted item's value is replaced with value .
另请参阅 insert ().
Swaps map other with this map. This operation is very fast and never fails.
该函数在 Qt 4.8 引入。
Returns a map that contains all the items in this map in addition to all the items in other . If a key is common to both maps, the resulting map will contain the key multiple times.
另请参阅 operator+= ().
Inserts all the items in the other map into this map and returns a reference to this map.
