std::multimap::multimap
From cppreference.com
(1) | ||
explicit multimap( const Compare& comp = Compare(),
const Allocator& alloc = Allocator() ); |
(until C++14) | |
multimap() : multimap( Compare() ) {}
explicit multimap( const Compare& comp, |
(since C++14) | |
explicit multimap( const Allocator& alloc );
|
(1) | (since C++11) |
(2) | ||
template< class InputIterator >
multimap( InputIterator first, InputIterator last, |
||
template< class InputIterator >
multimap( InputIterator first, InputIterator last, |
(since C++14) | |
multimap( const multimap& other );
|
(3) | |
multimap( const multimap& other, const Allocator& alloc );
|
(3) | (since C++11) |
multimap( multimap&& other );
|
(4) | (since C++11) |
multimap( multimap&& other, const Allocator& alloc );
|
(4) | (since C++11) |
(5) | ||
multimap( std::initializer_list<value_type> init,
const Compare& comp = Compare(), |
(since C++11) | |
multimap( std::initializer_list<value_type> init,
const Allocator& ); |
(since C++14) | |
Constructs new container from a variety of data sources and optionally using user supplied allocator alloc
or comparison function object comp
.
1) Default constructor. Constructs empty container.
2) Constructs the container with the contents of the range
[first, last)
.
3) Copy constructor. Constructs the container with the copy of the contents of
other
. If alloc
is not provided, allocator is obtained by calling std::allocator_traits<allocator_type>::select_on_copy_construction(other).
4) Move constructor. Constructs the container with the contents of
other
using move semantics. If alloc
is not provided, allocator is obtained by move-construction from the allocator belonging to other
.
5) Constructs the container with the contents of the initializer list
init
.
Contents |
[edit] Parameters
alloc | - | allocator to use for all memory allocations of this container |
comp | - | comparison function object to use for all comparisons of keys |
first, last | - | the range to copy the elements from |
other | - | another container to be used as source to initialize the elements of the container with |
init | - | initializer list to initialize the elements of the container with |
Type requirements | ||
-
InputIterator must meet the requirements of InputIterator .
|
||
-
Compare must meet the requirements of Compare .
|
||
-
Allocator must meet the requirements of Allocator .
|
[edit] Complexity
1) Constant
2) N log(N) where N = std::distance(first, last) in general, linear in
N
if the range is already sorted by value_comp()
.
3) Linear in size of
other
4) Constant. If
alloc
is given and alloc != other.get_allocator(), then linear.
5) N log(N) where N = init.size()) in general, linear in
N
if init
is already sorted by value_comp()
.[edit] Example
Run this code
#include <iostream> #include <string> #include <iomanip> #include <map> // helper function templates for printing each element template<typename CharT, typename Traits, typename T> void print_item(std::basic_ostream<CharT, Traits>& stream, const T& item) { stream << item; } template<typename CharT, typename Traits, typename Alloc> void print_item(std::basic_ostream<CharT, Traits>& stream, const std::basic_string<CharT, Traits, Alloc>& item) { stream << std::quoted(item); } // A printer for unordered maps template<typename Key, typename T, typename Compare, typename Allocator> std::ostream& operator<<(std::ostream& stream, const std::map<Key, T, Compare, Allocator>& map) { stream << '{'; char comma[3] = {'\0', ' ', '\0'}; for (const auto& pair : map) { stream << comma; print_item(stream, pair.first); stream << ':'; print_item(stream, pair.second); comma[0] = ','; } stream << '}'; return stream; } int main() { // (1) Default constructor std::map<std::string, int> map1; map1["something"] = 69; map1["anything"] = 199; map1["that thing"] = 50; std::cout << std::string(80, '-') << '\n'; std::cout << "map1 = " << map1 << '\n'; // (2) Iterator constructor std::map<std::string, int> iter(map1.find("anything"), map1.end()); std::cout << std::string(80, '-') << '\n'; std::cout << "iter = " << iter << '\n'; std::cout << "map1 = " << map1 << '\n'; // (3) Copy constructor std::map<std::string, int> copied(map1); std::cout << std::string(80, '-') << '\n'; std::cout << "copied = " << copied << '\n'; std::cout << "map1 = " << map1 << '\n'; // (4) Move constructor std::map<std::string, int> moved(std::move(map1)); std::cout << std::string(80, '-') << '\n'; std::cout << "moved = " << moved << '\n'; std::cout << "map1 = " << map1 << '\n'; // (5) Initializer list constructor const std::map<std::string, int> init { {"this", 100}, {"can", 100}, {"be", 100}, {"const", 100}, }; std::cout << std::string(80, '-') << '\n'; std::cout << "init = " << init << '\n'; }
Output:
-------------------------------------------------------------------------------- map1 = {"anything":199, "something":69, "that thing":50} -------------------------------------------------------------------------------- iter = {"anything":199, "something":69, "that thing":50} map1 = {"anything":199, "something":69, "that thing":50} -------------------------------------------------------------------------------- copied = {"anything":199, "something":69, "that thing":50} map1 = {"anything":199, "something":69, "that thing":50} -------------------------------------------------------------------------------- moved = {"anything":199, "something":69, "that thing":50} map1 = {} -------------------------------------------------------------------------------- init = {"be":100, "can":100, "const":100, "this":100}
[edit] See also
assigns values to the container (public member function) |