std::array::empty

 

C++

Language

Standard library headers

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Numerics library

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Regular expressions library (C++11)

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Thread support library (C++11)

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Technical Specifications

 

Containers library

array (C++11)

vector

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list

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std::array

Member functions

Element access

array::at

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Iterators

array::beginarray::cbegin

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array::rbeginarray::crbegin

array::rendarray::crend

Capacity

array::empty

array::size

array::max_size

Modifiers

array::fill

array::swap

Non-member functions

get

swap

operator==operator!=operator<operator>operator<=operator>=

Helper classes

tuple_size

tuple_element

 

constexpr bool empty();		(since C++11) (until C++14)
constexpr bool empty() const;		(since C++14)

Checks if the container has no elements, i.e. whether begin() == end().

Parameters

(none)

Return value

true if the container is empty, false otherwise

Exceptions

noexcept specification:  

noexcept

  

Complexity

Constant.

Example

The following code uses empty to check if a std::array contains any elements:

Run this code

#include <array>
#include <iostream>
 
int main()
{
    std::array<int, 4> numbers {3, 1, 4, 1};
    std::array<int, 0> no_numbers;
 
    std::cout << "numbers.empty(): " << numbers.empty() << '\n';
    std::cout << "no_numbers.empty(): " << no_numbers.empty() << '\n';
}

Output:

numbers.empty(): 0
no_numbers.empty(): 1

See also

size	returns the number of elements (public member function)