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

This container is an aggregate type with the same semantics as a struct holding aC-style arrayT[N] as its only non-static data member. Unlike a C-style array, it doesn't decay toT* automatically. As an aggregate type, it can be initialized withaggregate-initialization given at mostN initializers that are convertible toT: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.

std::array satisfies the requirements ofContainer andReversibleContainer except that default-constructed array is not empty and that the complexity of swapping is linear,satisfies the requirements ofContiguousContainer,(since C++17) and partially satisfies the requirements ofSequenceContainer.

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 callingfront() orback() on a zero-sized array is undefined.

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

[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 duringswap, the iterator will continue to point to the same array element, and will thus change its value.

[edit]Template parameters

[edit]Member types

[edit]Member functions

[edit]Non-member functions

[edit]Helper classes

[edit]Example

#include <algorithm>#include <array>#include <iostream>#include <iterator>#include <string> int main(){// Construction uses aggregate initialization    std::array<int,3> a1{{1,2,3}};// Double-braces required in C++11 prior to// the CWG 1270 revision (not needed in C++11// after the revision and in C++14 and beyond)     std::array<int,3> a2={1,2,3};// Double braces never required after = // Container operations are supportedstd::sort(a1.begin(), a1.end());    std::ranges::reverse_copy(a2,std::ostream_iterator<int>(std::cout," "));std::cout<<'\n'; // Ranged for loop is supported    std::array<std::string,2> a3{"E","\u018E"};for(constauto& s: a3)std::cout<< s<<' ';std::cout<<'\n'; // Deduction guide for array creation (since C++17)[[maybe_unused]] std::array a4{3.0,1.0,4.0};// std::array<double, 3> // Behavior of unspecified elements is the same as with built-in arrays[[maybe_unused]] std::array<int,2> a5;// No list init, a5[0] and a5[1]// are default initialized[[maybe_unused]] std::array<int,2> a6{};// List init, both elements are value// initialized, a6[0] = a6[1] = 0[[maybe_unused]] std::array<int,2> a7{1};// List init, unspecified element is value// initialized, a7[0] = 1, a7[1] = 0}

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[edit]See also

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