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std::array::empty

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< cpp‎ | container‎ | array
Revision as of 22:18, 2 November 2012 by P12bot (Talk | contribs)

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().

Contents

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:

#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

returns the number of elements
(public member function) [edit]