instance method

Date#<=>

(untyped other) -> ::Integer?

self <=> other → -1, 0, 1 or nil

static VALUE
d_lite_cmp(VALUE self, VALUE other)
{
    if (!k_date_p(other))
        return cmp_gen(self, other);

    {
        get_d2(self, other);

        if (!(simple_dat_p(adat) && simple_dat_p(bdat) &&
              m_gregorian_p(adat) == m_gregorian_p(bdat)))
            return cmp_dd(self, other);

        {
            VALUE a_nth, b_nth;
            int a_jd, b_jd;

            m_canonicalize_jd(self, adat);
            m_canonicalize_jd(other, bdat);
            a_nth = m_nth(adat);
            b_nth = m_nth(bdat);
            if (f_eqeq_p(a_nth, b_nth)) {
                a_jd = m_jd(adat);
                b_jd = m_jd(bdat);
                if (a_jd == b_jd) {
                    return INT2FIX(0);
                }
                else if (a_jd < b_jd) {
                    return INT2FIX(-1);
                }
                else {
                    return INT2FIX(1);
                }
            }
            else if (f_lt_p(a_nth, b_nth)) {
                return INT2FIX(-1);
            }
            else {
                return INT2FIX(1);
            }
        }
    }
}

Compares self and other, returning:

-1 if other is larger.
0 if the two are equal.
1 if other is smaller.
nil if the two are incomparable.

Argument other may be:

Another Date object:

Example

d = Date.new(2022, 7, 27) # => #<Date: 2022-07-27 ((2459788j,0s,0n),+0s,2299161j)>
prev_date = d.prev_day    # => #<Date: 2022-07-26 ((2459787j,0s,0n),+0s,2299161j)>
next_date = d.next_day    # => #<Date: 2022-07-28 ((2459789j,0s,0n),+0s,2299161j)>
d <=> next_date           # => -1
d <=> d                   # => 0
d <=> prev_date           # => 1

A DateTime object:

Example

d <=> DateTime.new(2022, 7, 26) # => 1
d <=> DateTime.new(2022, 7, 27) # => 0
d <=> DateTime.new(2022, 7, 28) # => -1

A numeric (compares self.ajd to other):

Example

d <=> 2459788 # => -1
d <=> 2459787 # => 1
d <=> 2459786 # => 1
d <=> d.ajd   # => 0

Any other object:

Example
```
d <=> Object.new # => nil
```

See also #<< #=== #- #>> also in 4.1 · 3.4 · 3.3 · 3.2 · 3.1 · 3.0

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