deductionguidesforstd::basic_string_view(3)

NAME
deductionguidesforstd::basic_string_view - deductionguidesforstd::basic_string_view

Synopsis
   Defined in header <string_view>
   template<class It, class End>
   basic_string_view(It, End) -> (1) (since C++20)
   basic_string_view<std::iter_value_t<It>>;
   template<class R>
   basic_string_view(R&&) -> (2) (since C++23)
   basic_string_view<ranges::range_value_t<R>>;
   These deduction guides are provided for std::basic_string_view.
   1) This deduction guide allow the character type to be deduced from the
   iterator-sentinel pair. This overload participates in overload resolution only if It
   satisfies contiguous_iterator and End satisfies sized_sentinel_for for It.
   2) This deduction guide allow the character type to be deduced from the range. This
   overload participates in overload resolution only if R satisfies contiguous_range.

Example
// Run this code
 #include <array>
 #include <iostream>
 #include <string_view>
 int main()
 {
     std::array a1 {'n', 'u', 'c', 'l', 'e', 'o', 'n', 's', ':', '\n'};
     std::basic_string_view s1(a1.cbegin(), a1.cend()); // deduction: CharT -> char
     static_assert(std::is_same_v<decltype(s1)::value_type, char>);
     std::cout << s1;
     std::array a2 {L'p', L'r', L'o', L't', L'o', L'n', L's', L'\n'};
     std::basic_string_view s2(a2.cbegin(), a2.cend()); // deduction: CharT -> wchar_t
     static_assert(std::is_same_v<decltype(s2)::value_type, wchar_t>);
     std::wcout << s2;
     std::array<long, 9> a3 {'n', 'e', 'u', 't', 'r', 'o', 'n', 's', '\n'};
     std::basic_string_view s3(a3.cbegin(), a3.cend()); // deduction: CharT -> long
     static_assert(std::is_same_v<decltype(s3)::value_type, long>);
     for (const auto e : s3) { std::cout << static_cast<char>(e); }
 }

Output:
 nucleons:
 protons
 neutrons