From cppreference.com
boolempty()constnoexcept;(since C++23)Checks if the underlying container has no elements. Equivalent to: returnbegin()==end();.
Return value
true if the underlying container is empty, false otherwise.
Complexity
Constant.
Example
The following code uses empty to check if a std::flat_multiset<int> contains any elements:
Run this code
#include<iostream>#include<flat_set>intmain(){std::flat_multiset<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 See also
returns the number of elements
(public member function)
(C++17)
checks whether the container is empty
(function template)