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

Defined in header `<chrono>`
constexpr std::chrono::hours operator""h( unsigned long long hrs );	(1)	(since C++14)
constexpr std::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

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.

Example

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

Output: