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std::array

From cppreference.com
< cpp‎ | container
Defined in header <array>
template<

    class T,
    std::size_t N

> struct array;
(since C++11)

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

This container is an aggregate type with the same semantics as a struct holding a C-style array T[N] as its only non-static data member. It can be initialized with aggregate-initialization, given at most N initializers that are convertible to T: std::array<int, 3> a = {1,2,3};

The struct combines the performance and accessibility of a C-style array with 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.

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

Contents

[edit] Iterator invalidation

As a rule, iterators to an array are never invalidated throughout the lifetime of the array. One should take note, however, that during swap, the iterator will continue to point to the same array element, and will thus change its value.

[edit] Member types

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

[edit] Member functions

Implicitly-defined member functions
(constructor)
(implicitly declared)
default-initializes or copy-initializes 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
access specified element with bounds checking
(public member function) [edit]
access specified element
(public member function) [edit]
access the first element
(public member function) [edit]
access the last element
(public member function) [edit]
direct access to the underlying array
(public member function) [edit]
Iterators
returns an iterator to the beginning
(public member function) [edit]
returns an iterator to the end
(public member function) [edit]
returns a reverse iterator to the beginning
(public member function) [edit]
returns a reverse iterator to the end
(public member function) [edit]
Capacity
checks whether the container is empty
(public member function) [edit]
returns the number of elements
(public member function) [edit]
returns the maximum possible number of elements
(public member function) [edit]
Operations
fill the container with specified value
(public member function) [edit]
swaps the contents
(public member function) [edit]

[edit] Non-member functions

lexicographically compares the values in the array
(function template) [edit]
accesses an element of an array
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]

[edit] Helper classes

obtains the size of an array
(class template specialization) [edit]
obtains the type of the elements of array
(class template specialization) [edit]

[edit] Example

#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, " "));
 
    std::cout << '\n';
 
    // ranged for loop is supported
    for(const auto& s: a3)
        std::cout << s << ' ';
}

Output:

3 2 1 
a b