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

 

C++

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Feature test macros (C++20)

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Concepts library (C++20)

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Technical specifications

Symbols index

External libraries

 

Strings library

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Classes

basic_string

basic_string_view (C++17)

char_traits

 

std::basic_string

Member functions basic_string::basic_string basic_string::~basic_string basic_string::operator= basic_string::assign basic_string::assign_range (C++23) basic_string::get_allocator Element access basic_string::at basic_string::operator[] basic_string::front (DR*) basic_string::back (DR*) basic_string::data basic_string::c_str basic_string::operator  basic_string_view (C++17) Iterators basic_string::beginbasic_string::cbegin (DR*) basic_string::endbasic_string::cend (DR*) basic_string::rbeginbasic_string::crbegin (DR*) basic_string::rendbasic_string::crend (DR*) Capacity basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit (DR*) Operations basic_string::clear basic_string::insert basic_string::insert_range (C++23) basic_string::erase basic_string::push_back basic_string::pop_back (DR*) basic_string::append basic_string::append_range (C++23) basic_string::operator+= basic_string::compare basic_string::replace basic_string::replace_with_range (C++23) basic_string::substr basic_string::copy basic_string::resize basic_string::resize_and_overwrite (C++23)   basic_string::swap

Search basic_string::starts_with (C++20) basic_string::ends_with (C++20) basic_string::contains (C++23) basic_string::find basic_string::rfind basic_string::find_first_of basic_string::find_first_not_of basic_string::find_last_of basic_string::find_last_not_of Constants basic_string::npos Deduction guides (C++17) Non-member functions operator+ swap(std::basic_string) operator""s (C++14) erase(std::basic_string)erase_if(std::basic_string) (C++20)(C++20) I/O operator<<operator>> getline Comparison operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) Numeric conversion stoistolstoll (C++11)(C++11)(C++11) stoulstoull (C++11)(C++11) stofstodstold (C++11)(C++11)(C++11) to_string (C++11) to_wstring (C++11) Helper classes hash<std::string>hash<std::wstring>hash<std::u32string>hash<std::u16string>hash<std::u8string> (C++11)  (C++11)(C++11)(C++11)(C++20) hash<std::pmr::string>hash<std::pmr::wstring>hash<std::pmr::u32string>hash<std::pmr::u16string>hash<std::pmr::u8string> (C++17)(C++17)(C++17)(C++17)(C++20)

 

Defined in header <string>
	(1)
std::string operator""s( const char *str, std::size_t len );			(since C++14) (until C++20)
constexpr std::string operator""s( const char *str, std::size_t len );			(since C++20)
constexpr std::u8string operator""s( const char8_t *str, std::size_t len );		(2)	(since C++20)
		(3)
std::u16string operator""s( const char16_t *str, std::size_t len );				(since C++14) (until C++20)
constexpr std::u16string operator""s( const char16_t *str, std::size_t len );				(since C++20)
			(4)
std::u32string operator""s( const char32_t *str, std::size_t len );					(since C++14) (until C++20)
constexpr std::u32string operator""s( const char32_t *str, std::size_t len );					(since C++20)
				(5)
std::wstring operator""s( const wchar_t *str, std::size_t len );						(since C++14) (until C++20)
constexpr std::wstring operator""s( const wchar_t *str, std::size_t len );						(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	Comment
__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 (C++17)	creates a string view of a character array literal (function)