map (STL/CLR)
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The latest version of this topic can be found at map (STL/CLR).
The template class describes an object that controls a varying-length sequence of elements that has bidirectional access. You use the container map to manage a sequence of elements as a (nearly) balanced ordered tree of nodes, each storing one element. An element consists of a key, for ordering the sequence, and a mapped value, which goes along for the ride.
In the description below, GValue is the same as:
Microsoft::VisualC::StlClr::GenericPair<GKey, GMapped>
where:
GKey is the same as Key unless the latter is a ref type, in which case it is Key^
GMapped is the same as Mapped unless the latter is a ref type, in which case it is Mapped^
Syntax
template<typename Key,
typename Mapped>
ref class map
: public
System::ICloneable,
System::Collections::IEnumerable,
System::Collections::ICollection,
System::Collections::Generic::IEnumerable<GValue>,
System::Collections::Generic::ICollection<GValue>,
System::Collections::Generic::IList<GValue>,
System::Collections::Generic::IDictionary<Gkey, GMapped>,
Microsoft::VisualC::StlClr::ITree<Gkey, GValue>
{ ..... };
Parameters
Key
The type of the key component of an element in the controlled sequence.
Mapped
The type of the additional component of an element in the controlled sequence.
Members
| Type Definition | Description |
|---|---|
| map::const_iterator (STL/CLR) | The type of a constant iterator for the controlled sequence. |
| map::const_reference (STL/CLR) | The type of a constant reference to an element. |
| map::const_reverse_iterator (STL/CLR) | The type of a constant reverse iterator for the controlled sequence. |
| map::difference_type (STL/CLR) | The type of a (possibly signed) distance between two elements. |
| map::generic_container (STL/CLR) | The type of the generic interface for the container. |
| map::generic_iterator (STL/CLR) | The type of an iterator for the generic interface for the container. |
| map::generic_reverse_iterator (STL/CLR) | The type of a reverse iterator for the generic interface for the container. |
| map::generic_value (STL/CLR) | The type of an element for the generic interface for the container. |
| map::iterator (STL/CLR) | The type of an iterator for the controlled sequence. |
| map::key_compare (STL/CLR) | The ordering delegate for two keys. |
| map::key_type (STL/CLR) | The type of an ordering key. |
| map::mapped_type (STL/CLR) | The type of the mapped value associated with each key. |
| map::reference (STL/CLR) | The type of a reference to an element. |
| map::reverse_iterator (STL/CLR) | The type of a reverse iterator for the controlled sequence. |
| map::size_type (STL/CLR) | The type of a (non-negative) distance between two elements. |
| map::value_compare (STL/CLR) | The ordering delegate for two element values. |
| map::value_type (STL/CLR) | The type of an element. |
| Member Function | Description |
|---|---|
| map::begin (STL/CLR) | Designates the beginning of the controlled sequence. |
| map::clear (STL/CLR) | Removes all elements. |
| map::count (STL/CLR) | Counts elements matching a specified key. |
| map::empty (STL/CLR) | Tests whether no elements are present. |
| map::end (STL/CLR) | Designates the end of the controlled sequence. |
| map::equal_range (STL/CLR) | Finds range that matches a specified key. |
| map::erase (STL/CLR) | Removes elements at specified positions. |
| map::find (STL/CLR) | Finds an element that matches a specified key. |
| map::insert (STL/CLR) | Adds elements. |
| map::key_comp (STL/CLR) | Copies the ordering delegate for two keys. |
| map::lower_bound (STL/CLR) | Finds beginning of range that matches a specified key. |
| map::make_value (STL/CLR) | Constructs a value object. |
| map::map (STL/CLR) | Constructs a container object. |
| map::rbegin (STL/CLR) | Designates the beginning of the reversed controlled sequence. |
| map::rend (STL/CLR) | Designates the end of the reversed controlled sequence. |
| map::size (STL/CLR) | Counts the number of elements. |
| map::swap (STL/CLR) | Swaps the contents of two containers. |
| map::to_array (STL/CLR) | Copies the controlled sequence to a new array. |
| map::upper_bound (STL/CLR) | Finds end of range that matches a specified key. |
| map::value_comp (STL/CLR) | Copies the ordering delegate for two element values. |
| Operator | Description |
|---|---|
| map::operator= (STL/CLR) | Replaces the controlled sequence. |
| map::operator(STL/CLR) | Maps a key to its associated mapped value. |
| operator!= (map) (STL/CLR) | Determines if a map object is not equal to another map object. |
| operator< (map) (STL/CLR) | Determines if a map object is less than another map object. |
| operator<= (map) (STL/CLR) | Determines if a map object is less than or equal to another map object. |
| operator== (map) (STL/CLR) | Determines if a map object is equal to another map object. |
| operator> (map) (STL/CLR) | Determines if a map object is greater than another map object. |
| operator>= (map) (STL/CLR) | Determines if a map object is greater than or equal to another map object. |
Interfaces
| Interface | Description |
|---|---|
| ICloneable | Duplicate an object. |
| IEnumerable | Sequence through elements. |
| ICollection | Maintain group of elements. |
| IEnumerable<T> | Sequence through typed elements. |
| ICollection<T> | Maintain group of typed elements. |
| IDictionary<TKey, TValue> | Maintain group of {key, value} pairs. |
| ITree<Key, Value> | Maintain generic container. |
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 map::key_compare (STL/CLR). You can specify the stored delegate object when you construct the map; 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 map::key_comp (STL/CLR)().
Such a delegate object must impose a strict weak ordering on keys of type map::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 map, an object of template class map does not require that keys for all elements are unique. (Two or more keys can have equivalent ordering.)
Each element contains a separate key and a mapped 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 map 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 map::end (STL/CLR)(). You can decrement this iterator to reach the last element in the controlled sequence, if present. You can increment a map 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 map element directly given its numerical position -- that requires a random-access iterator.
A map iterator stores a handle to its associated map node, which in turn stores a handle to its associated container. You can use iterators only with their associated container objects. A map iterator remains valid so long as its associated map node is associated with some map. 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/map>
Namespace: cliext
See Also
hash_map (STL/CLR)
hash_map (STL/CLR)
hash_multiset (STL/CLR)
hash_set (STL/CLR)
map
multiset (STL/CLR)
set (STL/CLR)
STL/CLR Library Reference