std::array

 

C++

Language

Standard library headers

Concepts

Utilities library

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Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

 

Containers library

array (C++11)

vector

deque

forward_list (C++11)

list

set

multiset

map

multimap

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

stack

queue

priority_queue

 

std::array

Member functions

Element access

array::at

array::operator[]

array::front

array::back

array::data

Iterators

array::begin array::cbegin

array::end array::cend

array::rbegin array::crbegin

array::rend array::crend

Capacity

array::empty

array::size

array::max_size

Modifiers

array::fill

array::swap

Non-member functions

get

swap

Helper classes

tuple_size

tuple_element

 

Defined in header <array>
template<     class T,     std::size_t N > struct array;		(since C++11)

std::array is a container that encapsulates constant size arrays.

This struct has the same aggregate type semantics as a C-style array. The size and efficiency of array<T,N> for some number of elements is equivalent to size and efficiency of the corresponding C-style array T[N]. The struct provides the benefits of a standard container, such as knowing its own size, supporting assignment, random access iterators, etc.

There is a special case for a zero-length array (N == 0). In that case, array.begin() == array.end(), which is some unique value. The effect of calling front() or back() on a zero-sized array is undefined.

array is an aggregate (it has no user-defined constructors and no private or protected members), which allows it to use aggregate-initialization.

An array can also be used as a tuple of N elements of the same type.

Member types

Member type	Definition
value_type	T
size_type	size_t
difference_type	ptrdiff_t
reference	value_type&
const_reference	const value_type&
pointer	T*
const_pointer	const T*
iterator	RandomAccessIterator
const_iterator	Constant random access iterator
reverse_iterator	std::reverse_iterator<iterator>
const_reverse_iterator	std::reverse_iterator<const_iterator>

Member functions

Implicitly-defined member functions
(constructor) (implicitly declared)	default-constructs or copy-constructs every element of the array (public member function)
(destructor) (implicitly declared)	destroys every element of the array (public member function)
operator= (implicitly declared)	overwrites every element of the array with the corresponding element of another array (public member function)
Element access
at	access specified element with bounds checking (public member function)
operator[]	access specified element (public member function)
front	access the first element (public member function)
back	access the last element (public member function)
data	direct access to the underlying array (public member function)
Iterators
begin cbegin	returns an iterator to the beginning (public member function)
end cend	returns an iterator to the end (public member function)
rbegin crbegin	returns a reverse iterator to the beginning (public member function)
rend crend	returns a reverse iterator to the end (public member function)
Capacity
empty	checks whether the container is empty (public member function)
size	returns the number of elements (public member function)
max_size	returns the maximum possible number of elements (public member function)
Operations
fill	fill the container with specified value (public member function)
swap	swaps the contents (public member function)

Non-member functions

operator== operator!= operator< operator<= operator> operator>=	lexicographically compares the values in the array (function template)
std::get(std::array)	accesses an element of an array (function template)
std::swap(std::array)	specializes the std::swap algorithm (function template)

Helper classes

std::tuple_size<std::array>	obtains the size of an array (class template specialization)
std::tuple_element<std::array>	obtains the type of the elements of array (class template specialization)

Example

run this code

#include <string>
#include <iterator>
#include <iostream>
#include <algorithm>
#include <array>
 
int main()
{
    // construction uses aggregate initialization
    std::array<int, 3> a1{ {1,2,3} };  // double-braces required
    std::array<int, 3> a2 = {1, 2, 3}; // except after =
    std::array<std::string, 2> a3 = { {std::string("a"), "b"} };
 
    // container operations are supported
    std::sort(a1.begin(), a1.end());
    std::reverse_copy(a2.begin(), a2.end(), std::ostream_iterator<int>(std::cout, " "));
 
    // ranged for loop is supported
    for(auto& s: a3)
        std::cout << s << ' ';
}

Output:

3 2 1 a b