NAME¶

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

Synopsis¶

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

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¶

// Run this code

#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:¶

one day is 24 hours (24h)
half an hour is 0.5 hours (0.5h)

See also¶

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