std::literals::chrono_literals::operator""h

Defined in header `<chrono>`
constexpr chrono::hours operator "" h(unsigned long long hrs);	(1)	(since C++14)
constexpr chrono::duration</unspecified/, std::ratio<3600,1>> operator "" h(long double hrs);	(2)	(since C++14)

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

1) integer literal, returns exactly std::chrono::hours(hrs)

2) floating-point literal, returns a floating-point duration equivalent to std::chrono::hours

Parameters

hrs

the number of hours

Return value

The std::chrono::duration literal.

Possible implementation

constexpr std::chrono::hours operator ""h(unsigned long long h)
{
    return std::chrono::hours(h);
}
constexpr std::chrono::duration<long double, ratio<3600,1>> operator ""h(long double h)
{
    return std::chrono::duration<long double, std::ratio<3600,1>>(h);
}

Notes

These operators are declared in the namespace std::literals::chrono_literals, where both literals and chrono_literals are inline namespaces. Access to these operators can be gained with using namespace std::literals, using namespace std::chrono_literals, and 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.

Example

#include <iostream>
#include <chrono>
 
int main()
{
    using namespace std::chrono_literals;
    auto day = 24h;
    auto halfhour = 0.5h;
    std::cout << "one day is " << day.count() << " hours\n"
              << "half an hour is " << halfhour.count() << " hours\n";
}

Output:

one day is 24 hours
half an hour is 0.5 hours