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

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

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

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

Return value

1) x. year ( ) == y. year ( ) && x. month ( ) == y. month ( )
2) x. year ( ) <=> y. year ( ) ! = 0 ? x. year ( ) <=> y. year ( ) : x. month ( ) <=> y. month ( )

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 <cassert>
#include <chrono>
#include <iostream>
 
int main()
{
    auto ymdl1{11/std::chrono::last/2020};
    auto mdl{std::chrono::last/std::chrono::November};
    auto ymdl2{mdl/2020};
    assert(ymdl1 == ymdl2);
 
    ymdl1 -= std::chrono::months{2};
    ymdl2 -= std::chrono::months{1};
    assert(ymdl1 < ymdl2);
}
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