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

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< cpp‎ | chrono

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

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>`)

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