std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>::empty
From cppreference.com
bool empty()constnoexcept; | (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_map<int, int> contains any elements:
Run this code
#include <iostream>#include <flat_map>#include <utility> int main(){std::flat_map<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) |
