# std::literals::string_view_literals::operator""sv

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< cpp‎ | string‎ | basic string view

Defined in header `<string_view>` |  |
constexpr std::string_view operator ""sv( const char* str, std::size_t len ) noexcept; | (1) | (since C++17)
constexpr std::u8string_view operator ""sv( const char8_t* str, std::size_t len ) noexcept; | (2) | (since C++20)
constexpr std::u16string_view operator ""sv( const char16_t* str, std::size_t len ) noexcept; | (3) | (since C++17)
constexpr std::u32string_view operator ""sv( const char32_t* str, std::size_t len ) noexcept; | (4) | (since C++17)
constexpr std::wstring_view operator ""sv( const wchar_t* str, std::size_t len ) noexcept; | (5) | (since C++17)

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) (C++17) | constructs a `basic_string_view` (public member function)
operator""s (C++14) | converts a character array literal to `basic_string` (function)

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