W3cubDocs

/C++

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

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

#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

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

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

Parameters

Return value

Notes

Example

See also