std::unordered_map<Key,T,Hash,KeyEqual,Allocator>::size
From cppreference.com
< cpp | container | unordered map
C++
Feature test macros (C++20)
Concepts library (C++20)
Metaprogramming library (C++11)
Ranges library (C++20)
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
Containers library
(C++17)
(C++11)
(C++26)
(C++26)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++23)
(C++23)
(C++23)
(C++23)
(C++20)
(C++23)
Tables
std::unordered_map
unordered_map::size
(C++17)
(C++17)
(C++23)
(C++17)
(C++17)
(C++20)
(until C++20)
Deduction guides (C++17)
size_type size() const noexcept;
(since C++11) (constexpr since C++26)
Returns the number of elements in the container.
Contents
[edit] Return value
std::distance (begin(), end())
[edit] Complexity
Constant.
[edit] Example
Run this code
#include <cassert> #include <unordered_map> int main() { std::unordered_map <int, char> nums{{1, 'a'}, {1, 'b'}, {2, 'c'}, {2, 'd'}}; assert (nums.size() == 2); }