Namespaces
Variants
Actions

std::map<Key,T,Compare,Allocator>::empty

From cppreference.com
< cpp‎ | container‎ | map
 
 
 
 
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::map<int, int> contains any elements:

#include <iostream>
#include <map>
#include <utility>
 
int main()
{
    std::map<int,int> numbers;
    std::cout << std::boolalpha;