php previous next week based on selected date - php

Question

I'm trying to create a simple weekly agenda. Here is my code:
$daterange = new DatePeriod(
new DateTime('2016-04-08'),
new DateInterval('P1D'),
new DateTime(date('Y-m-d',strtotime ( '1 week' , strtotime ( '2016-04-08' ) )))
);
Then a simple loop:
foreach ($daterange as $k => $row) {
echo $row->format('d') ." - " . $row->format('D') . "<br>";
}
Produces something like:
08 - Fri
09 - Sat
10 - Sun
11 - Mon
12 - Tue
13 - Wed
14 - Thu
Which works perfectly fine, but what I need is to display dates starting from Sunday or Monday, based on first day of the week. The desired result should be:
10 - Sun
11 - Mon
12 - Tue
13 - Wed
14 - Thu
15 - Fri
16 - Sat

Answer 1

You could use something like this:
date('Y-m-d', strtotime('last Monday', '2016-04-08'));
You can replace last Monday with next Monday/last Sunday/next Sunday, depending on what you need. This will give you the previous/next first day of the week for current day. You could then obtain a 7 day interval, starting from this date.

Answer 2

It is generally considered bad to mix DateTime and strtotime(), date(), etc., so here's another solution:
// The question is ambiguous on this, so we'll use a
// variable to configure the preferred first weekday
$firstWeekDay = 'Sunday';
$dateTime = new DateTime();
// If today isn't the first week day, get the last one
if ($dateTime->format('l') !== $firstWeekDay)
{
$dateTime->modify("last {$firstWeekDay}");
}
$period = new DatePeriod(
$dateTime,
new DateInterval('P1D'),
6 // Just tell PHP to create 6 (7 - the 1 start day) more dates
);