std::flat_multimap<Key,T,Compare,KeyContainer,MappedContainer>::empty
From cppreference.com
< cpp | container | flat multimap
bool empty() const noexcept; |
(since C++23) | |
Checks if the underlying containers have no elements. Equivalent to return begin() == end();.
Contents |
[edit] Parameters
(none)
[edit] Return value
true if the underlying containers are empty, false otherwise.
[edit] Complexity
Constant.
[edit] Example
The following code uses empty
to check if a std::flat_multimap<int, int> contains any elements:
Run this code
#include <iostream> #include <flat_map> #include <utility> int main() { std::flat_multimap<int,int> numbers; std::cout << std::boolalpha; std::cout << "Initially, numbers.empty(): " << numbers.empty() << '\n'; numbers.emplace(42, 13); numbers.insert(std::make_pair(13317, 123)); std::cout << "After adding elements, numbers.empty(): " << numbers.empty() << '\n'; }
Output:
Initially, numbers.empty(): true After adding elements, numbers.empty(): false
[edit] See also
returns the number of elements (public member function) | |
(C++17) |
checks whether the container is empty (function template) |