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 InputIt > multimap( InputIt first, InputIt last, |
||
| template< class InputIt > multimap( InputIt first, InputIt 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 | ||
-InputIt 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
other4) 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) |