std::array::at

From cppreference.com
< cpplrm; | containerlrm; | array

reference at( size_type pos );
(until C++17)
constexpr reference at( size_type pos );
(since C++17)
const_reference at( size_type pos ) const;
(until C++14)
constexpr const_reference at( size_type pos ) const;
(since C++14)

Returns a reference to the element at specified location pos, with bounds checking.

If pos is not within the range of the container, an exception of type std::out_of_range is thrown.

Parameters

pos - position of the element to return

Return value

Reference to the requested element.

Exceptions

std::out_of_range if !(pos < size()).

Complexity

Constant.

See also

access specified element
(public member function)