From cppreference.com
boolempty()const;(noexcept since C++11)Checks if the container has no elements, i.e., whether begin()==end().
Return value
true if the container is empty, false otherwise.
Complexity
Constant.
Example
The following code uses empty to check if a std::deque<int> contains any elements:
Run this code
#include<deque>#include<iostream>intmain(){std::deque<int>numbers;std::cout<<std::boolalpha;std::cout<<"Initially, numbers.empty(): "<<numbers.empty()<<'\n';numbers.push_back(42);numbers.push_back(13317);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)