What does this statement mean?

While ``` $w is an Array ( [0] => 4, [1] => 6 ) ``` what does this statement mean: ``` $day == $w[0] || $day == $w[1] || $day < ((7 + $w[1] - $w[0]) % 7); ``` Please help. I have not seen the `||` operator inside other than an if or while statement. Thank you. EDIT 01: This is the original function where it is used to find the number of a particular day in a date range: ``` // find number of a particular day (sunday or monday or etc) within a date range function number_of_days($day, $start, $end){ $w = array(date('w', $start), date('w', $end)); return floor( ( date('z', $end) - date('z', $start) ) / 7) + ($day == $w[0] || $day == $w[1] || $day < ((7 + $w[1] - $w[0]) % 7)); } ``` This was not created by me. But I wanted to edit this function because when the end day is a Saturday, it is taking the following Sunday into account too, which is wrong.