std::litera...:operator""s(3)

🌸 NAME 🌸

okay bestie, this is the page for std::literals::string_literals::operator""s — and literally the description is the same string again: std::literals::string_literals::operator""s. Iconic. It comes from the C++ Standard Libary manual, section (3), and it's all about forming a string literal of the desired type ✨

✨ Synopsis ✨

Defined in header <string>.

Here are the overloads, all exact and accounted for:

std::string operator""s( const char* str, std::size_t len );

(1) (since C++14), and (constexpr since C++20)

constexpr std::u8string operator""s( const char8_t* str, std::size_t len );

(2) (since C++20)

std::u16string operator""s( const char16_t* str, std::size_t len );

(3) (since C++14), and (constexpr since C++20)

std::u32string operator""s( const char32_t* str, std::size_t len );

(4) (since C++14), and (constexpr since C++20)

std::wstring operator""s( const wchar_t* str, std::size_t len );

(5) (since C++14), and (constexpr since C++20)

Forms a string literal of the desired type. The returns are literally:

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. Obsessed.

💅 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 tea ☕:

• __cpp_lib_string_udls — value 201304L, std (C++14), feature: 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 (C++17) — creates a string view of a character array literal (function).

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okay that's the whole vibe, bestie 🫶 source: http://cppreference.com, dated 2024.06.10, and the footer tag is std::litera...:operator""s(3) — periodt 💅