table of contents
std::unordered_multiset::empty(3) | C++ Standard Libary | std::unordered_multiset::empty(3) |
NAME¶
std::unordered_multiset::empty - std::unordered_multiset::empty
Synopsis¶
bool empty() const noexcept; (since C++11)
(until C++20)
[[nodiscard]] bool empty() const noexcept; (since C++20)
Checks if the container has no elements, i.e. whether begin() == end().
Parameters¶
(none)
Return value¶
true if the container is empty, false otherwise
Complexity¶
Constant.
Example¶
The following code uses empty to check if a
std::unordered_multiset<int> contains
any elements:
// Run this code
#include <unordered_set>
#include <iostream>
int main()
{
std::unordered_multiset<int> numbers;
std::cout << std::boolalpha;
std::cout << "Initially, numbers.empty(): " <<
numbers.empty() << '\n';
numbers.insert(42);
numbers.insert(13317);
std::cout << "After adding elements, numbers.empty(): "
<< numbers.empty() << '\n';
}
Output:¶
Initially, numbers.empty(): true
After adding elements, numbers.empty(): false
See also¶
size returns the number of elements
(C++11) (public member function)
empty checks whether the container is empty
(C++17) (function template)
2022.07.31 | http://cppreference.com |