std::set<Key,Compare,Allocator>::empty
From cppreference.com
bool empty()const; | (noexcept since C++11) (constexpr since C++26) | |
Checks if the container has no elements.
Contents |
[edit]Return value
true if the container is empty, false otherwise.
[edit]Complexity
Constant.
[edit]Example
The following code uses empty to check if a std::set<int> contains any elements:
Run this code
#include <iostream>#include <set> int main(){std::set<int> numbers;std::cout<<std::boolalpha;std::cout<<"Initially, numbers.empty(): "<< numbers.empty()<<'\n'; numbers.insert(42); numbers.insert(19937);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) |
