std::map

From Cppreference

C++ Standard Library
Language Utilities library Strings library Containers library Algorithms library Iterators library Numerics library Input/output library Localizations library Regular expressions library (C++11) Atomic operations library (C++11) Thread support library (C++11)
Containers library
array (C++11) vector deque forward_list (C++11) list set multiset map multimap unordered_set (C++11) unordered_multiset (C++11) unordered_map (C++11) unordered_multimap (C++11) stack queue priority_queue
std::map
Member functions map::map map::~map map::operator= map::get_allocator Element access map::at map::operator[] Iterators map::begin map::cbegin (C++11) map::end map::cend (C++11) map::rbegin map::crbegin (C++11) map::rend map::crend (C++11) Capacity map::empty map::size map::max_size Modifiers map::clear map::insert map::emplace (C++11) map::emplace_hint (C++11) map::erase map::swap Lookup map::count map::find map::equal_range map::lower_bound map::upper_bound Observers map::key_comp map::value_comp

Defined in header <map>
template<     class Key,     class T,     class Compare = std::less<Key>,     class Allocator = std::allocator<std::pair<const Key, T> > > class map;

Map is an associative container that contains a sorted list of unique key-value pairs. That list is sorted using the comparison function Compare applied to the keys. Search, removal, and insertion operations have logarithmic complexity. Maps are usually implemented as red-black trees.

Contents 1 Member types 2 Member classes 3 Member functions 3.1 Element access 3.2 Iterators 3.3 Capacity 3.4 Modifiers 3.5 Lookup 3.6 Observers 4 Non-member functions

[edit] Member types

Member type	Definition
key_type	Key
mapped_type	T
value_type	std::pair<const Key, T>
size_type	Unsigned integral type (usually size_t)
difference_type	Signed integer type (usually ptrdiff_t)
key_compare	Compare
allocator_type	Allocator
reference	Allocator::reference (until C++11) value_type& (since C++11)
const_reference	Allocator::const_reference (until C++11) const value_type& (since C++11)
pointer	T* (until C++11) std::allocator_traits<Allocator>::pointer (since C++11)
const_pointer	const T* (until C++11) std::allocator_traits<Allocator>::const_pointer (since C++11)
iterator	Bidirectional iterator
const_iterator	Constant bidirectional iterator
reverse_iterator	std::reverse_iterator<iterator>
const_reverse_iterator	std::reverse_iterator<const_iterator>

[edit] Member classes

value_compare	compares objects of type value_type (class)

[edit] Member functions

(constructor)	constructs the map (public member function)
(destructor)	destructs the map (public member function)
operator=	assigns values to the container (public member function)
get_allocator	returns the associated allocator (public member function)
Element access
at (C++11)	access specified element with bounds checking (public member function)
operator[]	access specified element (public member function)
Iterators
begin cbegin	returns an iterator to the beginning (public member function)
end cend	returns an iterator to the end (public member function)
rbegin crbegin	returns a reverse iterator to the beginning (public member function)
rend crend	returns a reverse iterator to the end (public member function)
Capacity
empty	checks whether the container is empty (public member function)
size	returns the number of elements (public member function)
max_size	returns the maximum possible number of elements (public member function)
Modifiers
clear	clears the contents (public member function)
insert	inserts elements (public member function)
emplace (C++11)	constructs element in-place (public member function)
emplace_hint (C++11)	constructs elements in-place using a hint (public member function)
erase	erases elements (public member function)
swap	swaps the contents (public member function)
Lookup
count	returns the number of elements matching specific key (public member function)
find	finds element with specific key (public member function)
equal_range	returns range of elements matching a specific key (public member function)
lower_bound	returns an iterator to the first element not less than the given value (public member function)
upper_bound	returns an iterator to the first element greater than a certain value (public member function)
Observers
key_comp	returns the function that compares keys (public member function)
value_comp	returns the function that compares keys (public member function)

[edit] Non-member functions

operator== operator!= operator< operator<= operator> operator>=	lexicographically compares the values in the container (function)
std::swap(std::map)	specializes the std::swap algorithm (function template)