NAME¶

std::literals::string_literals::operator""s - std::literals::string_literals::operator""s

Synopsis¶

Defined in header <string>
std::string operator""s( const char* str, std::size_t (1) (since C++14)
len ); (constexpr since C++20)
constexpr std::u8string operator""s( const char8_t* str, (2) (since C++20)
std::size_t len );
std::u16string operator""s( const char16_t* str, (3) (since C++14)
std::size_t len ); (constexpr since C++20)
std::u32string operator""s( const char32_t* str, (4) (since C++14)
std::size_t len ); (constexpr since C++20)
std::wstring operator""s( const wchar_t* str, (5) (since C++14)
std::size_t len ); (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}.

Parameters¶

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

Return value¶

The string literal.

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 either

* using namespace std::literals, or
* using namespace std::string_literals, or
* 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

Example¶

// Run this code

#include <iostream>
#include <string>

void print_with_zeros(auto const note, std::string const& 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 = "abc\0\0def";
std::string s2 = "abc\0\0def"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

See also¶

constructor constructs a basic_string
(public member function)
operator""sv creates a string view of a character array literal
(C++17) (function)