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

 

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std::chrono::duration

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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 duration classes, the duration literal operators become visible as well.

Example

Run this code

#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

See also

(constructor)

constructs new duration (public member function of std::chrono::duration)