std::literals::string_view_literals::operator""sv(3)

NAME
std::literals::string_view_literals::operator""sv - std::literals::string_view_literals::operator""sv

Synopsis
   Defined in header <string_view>
   constexpr std::string_view (1) (since C++17)
       operator ""sv( const char* str, std::size_t len ) noexcept;
   constexpr std::u8string_view (2) (since C++20)
       operator ""sv( const char8_t* str, std::size_t len ) noexcept;
   constexpr std::u16string_view
       operator ""sv( const char16_t* str, std::size_t len ) (3) (since C++17)
   noexcept;
   constexpr std::u32string_view
       operator ""sv( const char32_t* str, std::size_t len ) (4) (since C++17)
   noexcept;
   constexpr std::wstring_view (5) (since C++17)
       operator ""sv( const wchar_t* str, std::size_t len ) noexcept;
   Forms a string view of a character literal.
   1) Returns std::string_view{str, len}.
   2) Returns std::u8string_view{str, len}.
   3) Returns std::u16string_view{str, len}.
   4) Returns std::u32string_view{str, len}.
   5) Returns std::wstring_view{str, len}.

Parameters
   str - pointer to the beginning of the raw character array literal
   len - length of the raw character array literal

Return value
   The std::basic_string_view literal.

Notes
   These operators are declared in the namespace std::literals::string_view_literals,
   where both literals and string_view_literals are inline namespaces. Access to these
   operators can be gained with any of:
     * using namespace std::literals,
     * using namespace std::string_view_literals, or
     * using namespace std::literals::string_view_literals.

Example

// Run this code
 #include <iostream>
 #include <string_view>
 #include <typeinfo>

 void print_each_character(const std::string_view sw)
 {
     for (char c : sw)
         std::cout << (c == '\0' ? '@' : c);
     std::cout << '\n';
 }

 int main()
 {
     using namespace std::literals;

     std::string_view s1 = "abc\0\0def";
     std::string_view s2 = "abc\0\0def"sv;

     std::cout << "s1.size(): " << s1.size() << "; s1: ";
     print_each_character(s1);
     std::cout << "s2.size(): " << s2.size() << "; s2: ";
     print_each_character(s2);

     std::cout << "substr(1, 4): " << "abcdef"sv.substr(1, 4) << '\n';

     auto value_type_info = []<typename T>(T)
     {
         using V = typename T::value_type;
         std::cout << "sizeof " << typeid(V).name() << ": " << sizeof(V) << '\n';
     };

     value_type_info("char A"sv);
     value_type_info(L"wchar_t ∀"sv);
     value_type_info(u8"char8_t ∆"sv);
     value_type_info(u"char16_t ∇"sv);
     value_type_info(U"char32_t ∃"sv);
     value_type_info(LR"(raw ⊞)"sv);
 }

Possible output:
 s1.size(): 3; s1: abc
 s2.size(): 8; s2: abc@@def
 substr(1, 4): bcde
 sizeof char: 1
 sizeof wchar_t: 4
 sizeof char8_t: 1
 sizeof char16_t: 2
 sizeof char32_t: 4
 sizeof wchar_t: 4

See also
   constructor constructs a basic_string_view
                 (public member function)
   operator""s converts a character array literal to basic_string
   (C++14) (function)