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

Defined in header <chrono> 
constexpr bool operator==( const std::chrono::year_month& x,
                           const std::chrono::year_month& y ) noexcept;
 (1) (since C++20) 
constexpr std::strong_ordering operator<=>( const std::chrono::year_month& x,
                                            const std::chrono::year_month& y ) noexcept;
 (2) (since C++20)

Compares the two year_month values x and y.

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()

Example 

#include <iostream>
#include <chrono>
 
int main()
{
    using namespace std::chrono;
 
    constexpr year_month ym1 {year(2021), month(7)};
    constexpr year_month ym2 {year(2021)/7};
 
    std::cout << std::boolalpha << (ym1 == ym2) << '\n';
 
    static_assert(
        (2020y/1 < 2020y/2) && (2020y/2 == 2020y/2) && (2020y/3 <= 2021y/3)
     && (2023y/1 > 2020y/2) && (3020y/2 != 2020y/2) && (2020y/3 >= 2020y/3)
    );
}

Output:

true

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