std::unordered_multimap<Key,T,Hash,KeyEqual,Allocator>::size

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

vector<bool>

deque

forward_list (C++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

priority_queue

flat_set (C++23)

flat_multiset (C++23)

flat_map (C++23)

flat_multimap (C++23)

Views

span (C++20)

mdspan (C++23)

Iterator invalidation

Member function table

Non-member function table

 

std::unordered_multimap

Member types

Member functions

unordered_multimap::~unordered_multimap

unordered_multimap::operator=

unordered_multimap::get_allocator

Iterators

unordered_multimap::beginunordered_multimap::cbegin

unordered_multimap::endunordered_multimap::cend

Capacity

unordered_multimap::empty

unordered_multimap::size

unordered_multimap::max_size

Modifiers

unordered_multimap::clear

unordered_multimap::insert

unordered_multimap::insert_range (C++23)

unordered_multimap::emplace

unordered_multimap::emplace_hint

unordered_multimap::erase

unordered_multimap::swap

unordered_multimap::extract (C++17)

unordered_multimap::merge (C++17)

Lookup

unordered_multimap::count

unordered_multimap::find

unordered_multimap::contains (C++20)

unordered_multimap::equal_range

Bucket interface

unordered_multimap::begin(size_type)unordered_multimap::cbegin(size_type)

unordered_multimap::end(size_type)unordered_multimap::cend(size_type)

unordered_multimap::bucket_count

unordered_multimap::max_bucket_count

unordered_multimap::bucket_size

unordered_multimap::bucket

Hash policy

unordered_multimap::load_factor

unordered_multimap::max_load_factor

unordered_multimap::rehash

unordered_multimap::reserve

Observers

unordered_multimap::hash_function

unordered_multimap::key_eq

Non-member functions

operator==operator!= (until C++20)

std::swap

erase_if (C++20)

Deduction guides(C++17)

 

size_type size() const noexcept;		(since C++11)

Returns the number of elements in the container, i.e. std::distance(begin(), end()).

Parameters

(none)

Return value

The number of elements in the container.

Complexity

Constant.

Example

The following code uses size to display the number of elements in a std::unordered_multimap:

Run this code

#include <unordered_map>
#include <iostream>
 
int main()
{ 
    std::unordered_multimap<int,char> nums {{1, 'a'}, {3, 'b'}, {5, 'c'}, {7, 'd'}};
 
    std::cout << "nums contains " << nums.size() << " elements.\n";
}

Output:

nums contains 4 elements.

See also

empty (C++11)	checks whether the container is empty (public member function)
max_size (C++11)	returns the maximum possible number of elements (public member function)
sizessize (C++17)(C++20)	returns the size of a container or array (function template)