Arrays

std::array is a homogeneous container of fixed length. It needs the header <array>. The std::array combines the memory and runtime characteristic of a C array with the interface of std::vector. This means in particular, the std::array knows its size. You can use std::array in the algorithms of the STL.

You have to keep a few special rules in your mind to initialise a std::array.

std::array<int, 10> arr

The 10 elements are not initialised.

std::array<int, 10> arr{}

The 10 elements are default initialised.

std::array<int, 10> arr{1, 2, 3, 4, 5}

The remaining elements are default initialised.

std::array supports three types of index access.

arr[n];
arr.at(n);
std::get<n>(arr);

The most often used first type form with angle brackets does not check the boundaries of the arr. This is in opposition to arr.at(n). You will get eventually a std::range-error exception. The last type shows the relationship of the std::array...