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

From cppreference.com
< cpp‎ | chrono
 
 
 
 
 
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

Contents

[edit] Parameters

hrs - the number of hours

[edit] Return value

The std::chrono::duration literal.

[edit] 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);
}

[edit] 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 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.

[edit] Example

#include <iostream>
#include <chrono>
 
int main()
{
    using namespace std::literals::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

[edit] See also

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