std::literals::chrono_literals::operator""h - cppreference.com

##### cppreference.com

##### Search

Create account

##### Namespaces

- Page
- Discussion

##### Variants

##### Views

- View
- Edit
- History

##### Actions

# 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

### [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

Run this code

    #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

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

Retrieved from "http://en.cppreference.com/mwiki/index.php?title=cpp/chrono/operator%22%22h&oldid=68725"