给定年份的碳回收天数

Can Carbon return number of days for a given year?

    $dt = Carbon::parse($year . '-'. 1 .'-' . $from);

    var_dump($dt->format('z') + 1 );

this does not seems to work

echo 'Days in the year: ', 365 + $dt->format('L');

L: Whether it's a leap year; 1 if it is a leap year, 0 otherwise

You can do this by using a comparison

echo 'Days in the year: ', ($dt->isLeapYear() ? 366 : 365);