multiset (STL/CLR)

The template class describes an object that controls a varying-length sequence of elements that has bidirectional access. You use the container multiset to manage a sequence of elements as a (nearly) balanced ordered tree of nodes, each storing one element.

In the description below, GValue is the same as GKey, which in turn is the same as Key unless the latter is a ref type, in which case it is Key^.

template<typename Key>
    ref class multiset
        :   public
        System::ICloneable,
        System::Collections::IEnumerable,
        System::Collections::ICollection,
        System::Collections::Generic::IEnumerable<GValue>,
        System::Collections::Generic::ICollection<GValue>,
        System::Collections::Generic::IList<GValue>,
        Microsoft::VisualC::StlClr::ITree<Gkey, GValue>
    { ..... };

Parameters

• Key
  The type of the key component of an element in the controlled sequence.

Members

Interfaces

Remarks

The object allocates and frees storage for the sequence it controls as individual nodes. It inserts elements into a (nearly) balanced tree that it keeps ordered by altering the links between nodes, never by copying the contents of one node to another. That means you can insert and remove elements freely without disturbing remaining elements.

The object orders the sequence it controls by calling a stored delegate object of type multiset::key_compare (STL/CLR). You can specify the stored delegate object when you construct the multiset; if you specify no delegate object, the default is the comparison operator<(key_type, key_type). You access this stored object by calling the member function multiset::key_comp (STL/CLR)().

Such a delegate object must impose a strict weak ordering on keys of type multiset::key_type (STL/CLR). That means, for any two keys X and Y:

key_comp()(X, Y) returns the same Boolean result on every call.

If key_comp()(X, Y) is true, then key_comp()(Y, X) must be false.

If key_comp()(X, Y) is true, then X is said to be ordered before Y.

If !key_comp()(X, Y) && !key_comp()(Y, X) is true, then X and Y are said to have equivalent ordering.

For any element X that precedes Y in the controlled sequence, key_comp()(Y, X) is false. (For the default delegate object, keys never decrease in value.) Unlike template class set (STL/CLR), an object of template class multiset does not require that keys for all elements are unique. (Two or more keys can have equivalent ordering.)

Each element serves as both a ey and a value. The sequence is represented in a way that permits lookup, insertion, and removal of an arbitrary element with a number of operations proportional to the logarithm of the number of elements in the sequence (logarithmic time). Moreover, inserting an element invalidates no iterators, and removing an element invalidates only those iterators which point at the removed element.

A multiset supports bidirectional iterators, which means you can step to adjacent elements given an iterator that designates an element in the controlled sequence. A special head node corresponds to the iterator returned by multiset::end (STL/CLR)(). You can decrement this iterator to reach the last element in the controlled sequence, if present. You can increment a multiset iterator to reach the head node, and it will then compare equal to end(). But you cannot dereference the iterator returned by end().

Note that you cannot refer to a multiset element directly given its numerical position -- that requires a random-access iterator.

A multiset iterator stores a handle to its associated multiset node, which in turn stores a handle to its associated container. You can use iterators only with their associated container objects. A multiset iterator remains valid so long as its associated multiset node is associated with some multiset. Moreover, a valid iterator is dereferencable -- you can use it to access or alter the element value it designates -- so long as it is not equal to end().

Erasing or removing an element calls the destructor for its stored value. Destroying the container erases all elements. Thus, a container whose element type is a ref class ensures that no elements outlive the container. Note, however, that a container of handles does not destroy its elements.

Requirements

Header: <cliext/set>

Namespace: cliext

See Also

Reference

hash_map (STL/CLR)

hash_multiset (STL/CLR)

hash_multiset (STL/CLR)

hash_set (STL/CLR)

map (STL/CLR)

multiset (STL/CLR)

set (STL/CLR)

Other Resources

STL/CLR Library Reference