std::chrono::operator==,<=>(std::chrono::year_month_day)

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chrono I/O
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C-style date and time
 
std::chrono::year_month_day
 
Defined in header <chrono>
constexpr bool operator==( const std::chrono::year_month_day& x,
                           const std::chrono::year_month_day& y ) noexcept;
 (1) (since 哋它亢++20)
constexpr std::strong_ordering

    operator<=>( const std::chrono::year_month_day& x,

                 const std::chrono::year_month_day& y ) noexcept;
 (2) (since 哋它亢++20)

Compares the two year_month_day values x and y. This is a lexicographical comparison: the year() is compared first, then month(), then day().

The <, <=, >, >=, and != operators are synthesized from operator<=> and operator== respectively.

Return value

1) x.year() == y.year() && x.month() == y.month() && x.day() == y.day()
2) If x.year() <=> y.year != 0, x.year() <=> y.year; otherwise if x.month() <=> y.month() != 0, x.month() <=> y.month(); otherwise x.day() <=> y.day().

Notes

If both x and y represent valid dates (x.ok() && y.ok() == true), the result of the lexicographical comparison is consistent with the calendar order.

Example

Run this code
#include <chrono>
 
int main()
{
    constexpr auto ymd1{std::chrono::day(13)/7/1337};
    constexpr auto ymd2{std::chrono::year(1337)/7/13};
    static_assert(ymd1 == ymd2);
    static_assert(ymd1 <= ymd2);
    static_assert(ymd1 >= ymd2);
    static_assert(ymd1 <=> ymd2 == 0);
}
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