Get finish date, given start date and schedule in week

Question

I have a problem using PHP to get the finish date of course, as below:

Inputs:

• Start date (e.g: 8/23/2019)
• Schedule in week (e.g: Monday, Tuesday, Friday)
• Total of lessons (e.g: 8)

Output: The finish date of course (is 9/9/2019 with above e.g inputs).

One lesson is one day. Input fields from end user:

Sorry for my bad English. Thank you very much!

Answer 1

As I see it loop while there are lessons left and subtract when it's Monday, Tuesday or Friday.
After the loop output the date.

$start = "8/23/2019";
$days = ["Monday", "Tuesday", "Friday"];
$n = 8;

$d = strtotime($start);
while($n>0){
    //See if day is in days array
    if(in_array(date("l", $d), $days)){
        $n--;
    }
    $d += 86400; // go to next day
}

echo date("m/d/Y", $d-86400); //-86400 because  the loop adds one at the end.