PHP Recursion Function not working as expected [duplicate] - php

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How to use return inside a recursive function in PHP
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I have created a helper function to return the first valid payment date of the month. The day is not valid if it's a holiday (pulled from a list in a db table), a Saturday, or a Sunday. In this example the 1st January 2016 is a holiday.
I have created this recursive function in a CodeIgniter helper but I'm seeing really weird behaviour. What it should do is identify the 1st as a holiday, call itself to identify the 2nd as a Saturday, again to identify the 3rd as a Sunday, before eventually returning the 4th as the first valid day.
After the function calls itself, the part after the call will keep running in an infinite loop unless I insert a break;. If I do insert a break I get the following output:
2016-01-01: 1
2016-01-02: 2
2016-01-03: 3
Final: 2016-01-04: 4
Final: 2016-01-04: 4
Final: 2016-01-03: 3
Final: 2016-01-02: 2
before finally returning 2 (which is wrong).
function day_check($paymentDate, $paymentDay = 1) {
$CI =& get_instance();
$dateParts = explode("-", $paymentDate);
$holQ = $CI->db->query("SELECT * FROM holidays WHERE holidayDate = '$paymentDate'");
$holR = $holQ->row();
if ($paymentDay <= 0) {
$paymentDay = 1;
}
while (($holR->holidayDate == $paymentDate) || (date("l", strtotime($paymentDate)) == 'Saturday') || (date("l", strtotime($paymentDate)) == 'Sunday')) {
echo "$paymentDate: $paymentDay <br>";
$refinedDay = $dateParts[2] + 1;
if ($refinedDay < 10) {
$refinedDay = "0" . $refinedDay;
}
$paymentDate = $dateParts[0] . "-" . $dateParts[1] . "-" . ($refinedDay);
$paymentDay = $dateParts[2] + 1;
day_check($paymentDate, $paymentDay);
break;
}
echo "Final: $paymentDate: $paymentDay <br>";
return $paymentDay;
}
Initial $paymentDate provided to function is 2016-01-01
I've been looking at this for hours and I don't understand why this is happening. Is this a quirk of Codeigniter or do I completely misunderstand my recursion logic?

Answer 1

The problem is misunderstanding the logic. In your code the recursion call result is not used ever.
function day_check($paymentDate, $paymentDay = 1) {
$CI =& get_instance();
$dateParts = explode("-", $paymentDate);
$holQ = $CI->db->query("SELECT * FROM holidays WHERE holidayDate = '$paymentDate'");
$holR = $holQ->row();
if ($paymentDay <= 0) {
$paymentDay = 1;
}
// while -> if
if (($holR->holidayDate == $paymentDate) || (date("l", strtotime($paymentDate)) == 'Saturday') || (date("l", strtotime($paymentDate)) == 'Sunday')) {
echo "$paymentDate: $paymentDay <br>";
$refinedDay = $dateParts[2] + 1;
if ($refinedDay < 10) {
$refinedDay = "0" . $refinedDay;
}
$paymentDate = $dateParts[0] . "-" . $dateParts[1] . "-" . ($refinedDay);
$paymentDay = $dateParts[2] + 1;
return day_check($paymentDate, $paymentDay); // return!
// break; // no need
}
echo "Final: $paymentDate: $paymentDay <br>";
return $paymentDay;
}
Also change while to if since we don't need a loop there.