std::literals::string_literals::operator""s
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operator""s
(C++14)
(C++11)
Defined in header
<string>
std::string operator""s( const char* str, std::size_t len );
(1)
(since C++14) (constexpr since C++20)
constexpr std::u8string operator""s( const char8_t* str,
std::size_t len );
(2)
(since C++20)
std::size_t len );
std::u16string operator""s( const char16_t* str, std::size_t len );
(3)
(since C++14) (constexpr since C++20)
std::u32string operator""s( const char32_t* str, std::size_t len );
(4)
(since C++14) (constexpr since C++20)
std::wstring operator""s( const wchar_t* str, std::size_t len );
(5)
(since C++14) (constexpr since C++20)
Forms a string literal of the desired type.
1) Returns std::string {str, len}.
2) Returns std::u8string {str, len}.
3) Returns std::u16string {str, len}.
4) Returns std::u32string {str, len}.
5) Returns std::wstring {str, len}.
Contents
[edit] Parameters
str
-
pointer to the beginning of the raw character array literal
len
-
length of the raw character array literal
[edit] Return value
The string literal.
[edit] Notes
These operators are declared in the namespace std::literals::string_literals, where both literals and string_literals are inline namespaces. Access to these operators can be gained with any of the following using directives:
- using namespace std::literals
- using namespace std::string_literals
- using namespace std::literals::string_literals
std::chrono::duration also defines operator""s to represent literal seconds, but it is an arithmetic literal: 10.0s and 10s are ten seconds, but "10"s is a string.
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_string_udls |
201304L |
(C++14) | User-defined literals for string types |
[edit] Example
Run this code
#include <iostream> #include <string> void print_with_zeros(const auto note, const std::string & s) { std::cout << note; for (const char c : s) c ? std::cout << c : std::cout << "0"; std::cout << " (size = " << s.size() << ")\n"; } int main() { using namespace std::string_literals; std::string s1 = "abc0円0円def"; std::string s2 = "abc0円0円def"s; print_with_zeros("s1: ", s1); print_with_zeros("s2: ", s2); std::cout << "abcdef"s.substr(1,4) << '\n'; }
Output:
s1: abc (size = 3) s2: abc00def (size = 8) bcde