PHP: find dates every week for different days - php

Question

I am trying to solve a problem I am looking for hours into.
My students have special courses and I am trying to find the dates.
For example:
Student 1 in Class A: every Monday from Jan 1st till April 1st
Student 2 in Class B: every Wednesday from April 1st until June...
So I programmed a function in which I can pass info like begin, end, weekday to show me the dates:
function tkcheck ($beginnfunc,$endfunc,$daycheck)
{
$begin = new DateTime($beginnfunc);
$end = new DateTime($endfunc);
$interval = new DateInterval('P1W');
$period = new DatePeriod($begin, $interval, $end);
foreach ($period as $date) {
$dayw = $date->modify($daycheck);
if ($dayw < $end) {
$daystring = $dayw->format ('d-m-Y');
$q1day1[] = $daystring;
}
}
}
tkcheck ('2022-02-20','2022-04-01','next Wednesday');
print_r($q1day1);
But print_r does not show me any information when I try to use my function tkcheck...
Maybe some here might help me, thank you!

Answer 1

$q1day1 is scoped within the function. It is not accessible out of the function.
To fix this return the variable.
function tkcheck ($beginnfunc,$endfunc,$daycheck)
{
$begin = new DateTime($beginnfunc);
$end = new DateTime($endfunc);
$interval = new DateInterval('P1W');
$period = new DatePeriod($begin, $interval, $end);
foreach ($period as $date) {
$dayw = $date->modify($daycheck);
if ($dayw < $end) {
$daystring = $dayw->format ('d-m-Y');
$q1day1[] = $daystring;
}
}
return $q1day1;
}
$result = tkcheck ('2022-02-20','2022-04-01','next wednesday');
print_r($result);
See Variable Scope for more info.

Answer 2

The special feature of this solution is simply to create a Date::Interval from 'next Monday'.
$start = date_create('Jan 1st 2022')->modify('-1 Day');
$end = date_create('Apr 1st 2022');
$interval = DateInterval::createFromDateString('next Monday');
$period = new DatePeriod($start, $interval, $end, DatePeriod::EXCLUDE_START_DATE);
$dateArray = iterator_to_array ($period);
echo '<pre>'.var_export($dateArray,true).'</pre>';
The modification with "-1 Day" is necessary to record a Monday that falls exactly on the start date.