std::basic_string_view::substr

From cppreference.com
constexpr basic_string_view
substr(size_type pos = 0, size_type count = npos ) const;
(since C++17)

Returns a view of the substring [pos, pos + rcount), where rcount is the smaller of count and size() - pos.

Parameters

pos - position of the first character
count - requested length

Return value

View of the substring [pos, pos + rcount).

Exceptions

std::out_of_range if pos > size()

Complexity

Constant.

See also

copies characters
(public member function)
find characters in the view
(public member function)