find out how many weekend in a date range - php

Question

for example I have two dates 2015-10-28 and 2015-12-31. from these I want to know how many saturday and sunday in that given date range. I can find the diff between that dates but I can't find how many weekends.
anyone ever made this?
here is my current code:
function createDateRange($maxDate, $cell, $lead, $offArray = array()){
$dates = [];
--$cell;
--$lead;
$edate = date('Y-m-d', strtotime($maxDate." -$lead day"));
$sdate = date('Y-m-d', strtotime($edate." -$cell day"));
$start = new DateTime($sdate);
$end = new DateTime($edate);
$end = $end->modify('+1 day');
$interval = DateInterval::createFromDateString('1 day');
$period = new DatePeriod($start, $interval, $end);
foreach($period as $d){
$dt = $d->format('Y-m-d');
if(!in_array($dt, $dates)){
$dates[] = $dt;
}
}
return $dates;
}
basically I want to add sat+sun count to the date range.

Answer 1

The trick is to use an O(1)-type algorithm to solve this.
Given your starting date, move to the first Saturday. Call that from
Given your ending date, move back to the previous Friday. Call that to
Unless you have an edge case (where to is less than from), compute (to - from) * 2 / 7 as the number of weekend days, and add that to any weekend days passed over in steps (1) and (2).
This is how I do it in production, although generalised for arbitrary weekend days.

Answer 2

Use this function:
function getDateForSpecificDayBetweenDates($startDate, $endDate, $weekdayNumber)
{
$startDate = strtotime($startDate);
$endDate = strtotime($endDate);
$dateArr = array();
do
{
if(date("w", $startDate) != $weekdayNumber)
{
$startDate += (24 * 3600); // add 1 day
}
} while(date("w", $startDate) != $weekdayNumber);
while($startDate <= $endDate)
{
$dateArr[] = date('Y-m-d', $startDate);
$startDate += (7 * 24 * 3600); // add 7 days
}
return($dateArr);
}
The function call to get dates for all Sunday's in year 2015:
$dateArr = getDateForSpecificDayBetweenDates('2015-01-01', '2015-12-31', 0);
print "<pre>";
print_r($dateArr);

Answer 3

//周日0 周一1 .....
$data = 4;//周四
$t1 ='2015-10-28';
$t2 = '2015-12-31';
$datetime1 = date_create($t1);
$datetime2 = date_create($t2);
$interval = date_diff($datetime1, $datetime2);
$day = $interval->format('%a');
$result = ($day)/7;
$start = getdate(strtotime($t1))['wday'];
$end = getdate(strtotime($t2))['wday'];
if($data>=$start && $data<=$end){
echo floor($result)+1;
}else{
echo floor($result);
}