The QSet class is a template class that provides a hash-table-based set. 更多...
| 头： | #include <QSet> |
注意： 此类的所有函数 可重入 .
| class | const_iterator |
| class | iterator |
| typedef | ConstIterator |
| typedef | Iterator |
| typedef | const_pointer |
| typedef | const_reference |
| typedef | difference_type |
| typedef | key_type |
| typedef | pointer |
| typedef | reference |
| typedef | size_type |
| typedef | value_type |
| QSet () | |
| QSet (const QSet<T> & other ) | |
| const_iterator | begin () const |
| iterator | begin () |
| int | capacity () const |
| void | clear () |
| const_iterator | constBegin () const |
| const_iterator | constEnd () const |
| const_iterator | constFind (const T & value ) const |
| bool | contains (const T & value ) const |
| bool | contains (const QSet<T> & other ) const |
| int | count () const |
| bool | empty () const |
| const_iterator | end () const |
| iterator | end () |
| iterator | erase (iterator pos ) |
| const_iterator | find (const T & value ) const |
| iterator | find (const T & value ) |
| const_iterator | insert (const T & value ) |
| QSet<T> & | intersect (const QSet<T> & other ) |
| bool | isEmpty () const |
| bool | remove (const T & value ) |
| void | reserve (int size ) |
| int | size () const |
| void | squeeze () |
| QSet<T> & | subtract (const QSet<T> & other ) |
| void | swap (QSet<T> & other ) |
| QList<T> | toList () const |
| QSet<T> & | unite (const QSet<T> & other ) |
| QList<T> | values () const |
| bool | operator!= (const QSet<T> & other ) const |
| QSet<T> | operator& (const QSet<T> & other ) const |
| QSet<T> & | operator&= (const QSet<T> & other ) |
| QSet<T> & | operator&= (const T & value ) |
| QSet<T> | operator+ (const QSet<T> & other ) const |
| QSet<T> & | operator+= (const QSet<T> & other ) |
| QSet<T> & | operator+= (const T & value ) |
| QSet<T> | operator- (const QSet<T> & other ) const |
| QSet<T> & | operator-= (const QSet<T> & other ) |
| QSet<T> & | operator-= (const T & value ) |
| QSet<T> & | operator<< (const T & value ) |
| QSet<T> & | operator= (const QSet<T> & other ) |
| QSet<T> & | operator= (QSet<T> && other ) |
| bool | operator== (const QSet<T> & other ) const |
| QSet<T> | operator| (const QSet<T> & other ) const |
| QSet<T> & | operator|= (const QSet<T> & other ) |
| QSet<T> & | operator|= (const T & value ) |
| QSet<T> | fromList (const QList<T> & list ) |
| QDataStream & | operator<< (QDataStream & out , const QSet<T> & set ) |
| QDataStream & | operator>> (QDataStream & in , QSet<T> & set ) |
The QSet class is a template class that provides a hash-table-based set.
QSet <T> is one of Qt's generic 容器类 . It stores values in an unspecified order and provides very fast lookup of the values. Internally, QSet <T> is implemented as a QHash .
QSet<QString> set;
要将值插入集，使用 insert ():
set.insert("one"); set.insert("three"); set.insert("seven");
将项插入集的另一方式是使用 operator<<()：
set << "twelve" << "fifteen" << "nineteen";
要测试项是否属于集，使用 contains ():
if (!set.contains("ninety-nine")) ...
If you want to navigate through all the values stored in a QSet , you can use an iterator. QSet supports both Java 风格迭代器 ( QSetIterator and QMutableSetIterator ) 和 STL 样式迭代器 ( QSet::iterator and QSet::const_iterator ). Here's how to iterate over a QSet < QWidget *> using a Java-style iterator:
QSetIterator<QWidget *> i(set); while (i.hasNext()) qDebug() << i.next();
Here's the same code, but using an STL-style iterator:
QSet<QWidget *>::const_iterator i = set.constBegin(); while (i != set.constEnd()) { qDebug() << *i; ++i; }
QSet is unordered, so an iterator's sequence cannot be assumed to be predictable. If ordering by key is required, use a QMap .
To navigate through a QSet ，还可以使用 foreach :
QSet<QString> set; ... foreach (const QString &value, set) qDebug() << value;
Items can be removed from the set using remove (). There is also a clear () function that removes all items.
QSet
's value data type must be an
可赋值数据类型
。例如，无法存储
QWidget
作为值；取而代之，存储
QWidget
*. In addition, the type must provide
operator==()
, and there must also be a global
qHash
() function that returns a hash value for an argument of the key's type. See the
QHash
documentation for a list of types supported by
qHash
().
在内部， QSet uses a hash table to perform lookups. The hash table automatically grows and shrinks to provide fast lookups without wasting memory. You can still control the size of the hash table by calling reserve (), if you already know approximately how many elements the QSet will contain, but this isn't necessary to obtain good performance. You can also call capacity () to retrieve the hash table's size.
另请参阅 QSetIterator , QMutableSetIterator , QHash ，和 QMap .
Qt 样式同义词 QSet::const_iterator .
Qt 样式同义词 QSet::iterator .
该 typedef 在 Qt 4.2 引入。
Typedef for const T *. Provided for STL compatibility.
Typedef for const T &. Provided for STL compatibility.
Typedef for const ptrdiff_t. Provided for STL compatibility.
typedef 对于 T。为兼容 STL 提供。
Typedef for T *. Provided for STL compatibility.
Typedef for T &. Provided for STL compatibility.
typedef 对于 int。为兼容 STL 提供。
typedef 对于 T。为兼容 STL 提供。
构造空集。
另请参阅 clear ().
构造副本为 other .
This operation occurs in 常量时间 ，因为 QSet is 隐式共享 . This makes returning a QSet from a function very fast. If a shared instance is modified, it will be copied (copy-on-write), and this takes 线性时间 .
另请参阅 operator= ().
Returns a const STL-style iterator positioned at the first item in the set.
另请参阅 constBegin () 和 end ().
这是重载函数。
Returns a non-const STL-style iterator positioned at the first item in the set.
该函数在 Qt 4.2 引入。
Returns the number of buckets in the set's internal hash table.
The sole purpose of this function is to provide a means of fine tuning QSet 's memory usage. In general, you will rarely ever need to call this function. If you want to know how many items are in the set, call size ().
从集移除所有元素。
另请参阅 remove ().
Returns a const STL-style iterator positioned at the first item in the set.
Returns a const STL-style iterator pointing to the imaginary item after the last item in the set.
另请参阅 constBegin () 和 end ().
Returns a const iterator positioned at the item value in the set. If the set contains no item value ，函数返回 constEnd ().
该函数在 Qt 4.2 引入。
Returns true if the set contains item value ；否则返回 false。
另请参阅 insert (), remove ()，和 find ().
Returns true if the set contains all items from the other set; otherwise returns false.
该函数在 Qt 4.6 引入。
另请参阅 insert (), remove ()，和 find ().
如同 size ().
Returns true if the set is empty. This function is provided for STL compatibility. It is equivalent to isEmpty ().
Returns a const STL-style iterator positioned at the imaginary item after the last item in the set.
这是重载函数。
Returns a non-const STL-style iterator pointing to the imaginary item after the last item in the set.
该函数在 Qt 4.2 引入。
Removes the item at the iterator position pos from the set, and returns an iterator positioned at the next item in the set.
不像 remove (), this function never causes QSet to rehash its internal data structure. This means that it can safely be called while iterating, and won't affect the order of items in the set.
该函数在 Qt 4.2 引入。
Returns a const iterator positioned at the item value in the set. If the set contains no item value ，函数返回 constEnd ().
该函数在 Qt 4.2 引入。
另请参阅 constFind () 和 contains ().
这是重载函数。
Returns a non-const iterator positioned at the item value in the set. If the set contains no item value ，函数返回 end ().
该函数在 Qt 4.2 引入。
[static]
QSet
<
T
> QSet::
fromList
(const
QList
<
T
> &
list
)
返回新的 QSet object containing the data contained in list 。由于 QSet doesn't allow duplicates, the resulting QSet might be smaller than the list ，因为 QList can contain duplicates.
范例：
QStringList list; list << "Julia" << "Mike" << "Mike" << "Julia" << "Julia"; QSet<QString> set = QSet<QString>::fromList(list); set.contains("Julia"); // returns true set.contains("Mike"); // returns true set.size(); // returns 2
另请参阅 toList () 和 QList::toSet ().
Inserts item value into the set, if value isn't already in the set, and returns an iterator pointing at the inserted item.
另请参阅 operator<< (), remove ()，和 contains ().
Removes all items from this set that are not contained in the other set. A reference to this set is returned.
另请参阅 operator&= (), unite ()，和 subtract ().
Returns true if the set contains no elements; otherwise returns false.
另请参阅 size ().
删除任何出现的项 value from the set. Returns true if an item was actually removed; otherwise returns false.
Ensures that the set's internal hash table consists of at least size buckets.
This function is useful for code that needs to build a huge set and wants to avoid repeated reallocation. For example:
QSet<QString> set; set.reserve(20000); for (int i = 0; i < 20000; ++i) set.insert(values[i]);
Ideally, size should be slightly more than the maximum number of elements expected in the set. size doesn't have to be prime, because QSet will use a prime number internally anyway. If size is an underestimate, the worst that will happen is that the QSet will be a bit slower.
In general, you will rarely ever need to call this function. QSet 's internal hash table automatically shrinks or grows to provide good performance without wasting too much memory.
另请参阅 squeeze () 和 capacity ().
Returns the number of items in the set.
Reduces the size of the set's internal hash table to save memory.
The sole purpose of this function is to provide a means of fine tuning QSet 's memory usage. In general, you will rarely ever need to call this function.
另请参阅 reserve () 和 capacity ().
Removes all items from this set that are contained in the other set. Returns a reference to this set.
另请参阅 operator-= (), unite ()，和 intersect ().
Swaps set other with this set. This operation is very fast and never fails.
该函数在 Qt 4.8 引入。
返回新的 QList containing the elements in the set. The order of the elements in the QList is undefined.
范例：
QSet<QString> set; set << "red" << "green" << "blue" << ... << "black"; QList<QString> list = set.toList(); qSort(list);
另请参阅 fromList (), QList::fromSet ()，和 qSort ().
Each item in the other set that isn't already in this set is inserted into this set. A reference to this set is returned.
另请参阅 operator|= (), intersect ()，和 subtract ().
返回新的 QList containing the elements in the set. The order of the elements in the QList is undefined.
这如同 toList ().
另请参阅 fromList (), QList::fromSet ()，和 qSort ().
返回 true 若 other set is not equal to this set; otherwise returns false.
Two sets are considered equal if they contain the same elements.
This function requires the value type to implement
operator==()
.
另请参阅 operator== ().
返回新的 QSet that is the intersection of this set and the other set.
另请参阅 intersect (), operator&= (), operator| ()，和 operator- ().
如同 intersect( other ).
另请参阅 operator& (), operator|= ()，和 operator-= ().
这是重载函数。
如同 intersect( other ), if we consider other to be a set that contains the singleton value .
返回新的 QSet that is the union of this set and the other set.
另请参阅 unite (), operator|= (), operator& ()，和 operator- ().
Same as unite( other ).
另请参阅 operator| (), operator&= ()，和 operator-= ().
Inserts a new item value and returns a reference to the set. If value already exists in the set, the set is left unchanged.
另请参阅 insert ().
返回新的 QSet that is the set difference of this set and the other set, i.e., this set - other set.
另请参阅 subtract (), operator-= (), operator| ()，和 operator& ().
如同 subtract( other ).
另请参阅 operator- (), operator|= ()，和 operator&= ().
Removes the occurrence of item value from the set, if it is found, and returns a reference to the set. If the value is not contained the set, nothing is removed.
另请参阅 remove ().
Inserts a new item value and returns a reference to the set. If value already exists in the set, the set is left unchanged.
另请参阅 insert ().
赋值 other set to this set and returns a reference to this set.
返回 true 若 other set is equal to this set; otherwise returns false.
Two sets are considered equal if they contain the same elements.
This function requires the value type to implement
operator==()
.
另请参阅 operator!= ().
返回新的 QSet that is the union of this set and the other set.
另请参阅 unite (), operator|= (), operator& ()，和 operator- ().
Same as unite( other ).
另请参阅 operator| (), operator&= ()，和 operator-= ().
Inserts a new item value and returns a reference to the set. If value already exists in the set, the set is left unchanged.
另请参阅 insert ().
写入 set 到流 out .
This function requires the value type to implement
operator<<()
.
另请参阅 QDataStream 运算符格式 .
读取集从流 in into set .
This function requires the value type to implement
operator>>()
.
另请参阅 QDataStream 运算符格式 .