Defined in header <chrono>
constexpr std::chrono::seconds operator ""s( unsigned long long secs );
(1) (since C++14)
constexpr std::chrono::duration</*unspecified*/>
                               operator ""s( long double secs );
(2) (since C++14)

Forms a std::chrono::duration literal representing seconds.

1) integer literal, returns exactly std::chrono::seconds(secs)
2) floating-point literal, returns a floating-point duration equivalent to std::chrono::seconds


secs - the number of seconds

Return value

The std::chrono::duration literal.

Possible implementation

constexpr std::chrono::seconds operator ""s(unsigned long long s)
    return std::chrono::seconds(s);
constexpr std::chrono::duration<long double> operator ""s(long double s)
    return std::chrono::duration<long double>(s);


This operator is declared in the namespace std::literals::chrono_literals, where both literals and chrono_literals are inline namespaces. Access to this operator can be gained with:

  • using namespace std::literals,
  • using namespace std::chrono_literals, or
  • using namespace std::literals::chrono_literals.

In addition, within the namespace std::chrono, the directive using namespace literals::chrono_literals; is provided by the standard library, so that if a programmer uses using namespace std::chrono; to gain access to the classes in the chrono library, the corresponding literal operators become visible as well.

std::string also defines operator""s, to represent literal objects of type std::string, but it is a string literal: 10s is ten seconds, but "10"s is a two-character string.


#include <iostream>
#include <chrono>
int main()
    using namespace std::chrono_literals;
    std::chrono::seconds halfmin = 30s;
    std::cout << "Half a minute is " << halfmin.count() << " seconds.\n"
        "A minute and a second is " << (1min + 1s).count() << " seconds.\n";
    std::chrono::duration moment = 0.1s;
    std::cout << "A moment is " << moment.count() << " seconds.\n"
        "And thrice as much is " << (moment + 0.2s).count() << " seconds.\n";


Half a minute is 30 seconds.
A minute and a second is 61 seconds.
A moment is 0.1 seconds.
And thrice as much is 0.3 seconds.

See also

constructs new duration
(public member function of std::chrono::duration<Rep,Period>)

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