std::literals::chrono_literals::operator""d

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C-style date and time
std::chrono::day
Defined in header <chrono>
constexpr std::chrono::day operator ""d( unsigned long long d ) noexcept ;
(since C++20)

Forms a std::chrono::day literal representing a day of the month in the calendar.

Parameters

d - the day value

Return value

A std::chrono::day storing d. If d > 255

Possible implementation

constexpr std::chrono::day operator ""d(unsigned long long d) noexcept
{
    return std::chrono::day(d);
}

Notes

This operator is declared in the namespace std::literals::chrono_literals, where both literals and chrono_literals are inline namespaces

  • 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

Example

Run this code
#include <chrono>
#include <iostream>
 
int main()
{
    using namespace std::literals::chrono_literals;
 
    std::cout << static_cast<unsigned>(42d) << '\t' << 42d << '\n'
              << static_cast<unsigned>(256d) << '\t' << 256d << '\n' // unspecified
              << static_cast<unsigned>(298d) << '\t' << 298d << '\n'; // unspecified
}

Possible output: 

42      42 is not a valid day
0       00 is not a valid day
42      42 is not a valid day

See also

 constructs a day
(public member function of std::chrono::day)
retrieves the stored day value
(public member function of std::chrono::day)
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