PHP What is wrong with recursive function?

Question

i did function for showing today date or next workday date, if is weekend. Function works great, but with return is something wrong.

$today = todayDate('2014-10-18'); // Saturday

    function todayDate($date) {
        if(date('N', strtotime($date)) >= 6) {
            echo 'If - ' . $date . '<br/>';
            $date = date('Y-m-d', strtotime('+1 day', strtotime($date)));
            todayDate($date);
        } else {
            echo 'Else - ' . $date . '<br/>';               
        }
        return $date;
    }

    echo '<br/><br/>Today: ' . $today . '<br/><br/>';

This function echoes following:

If - 2014-10-18
If - 2014-10-19
Else - 2014-10-20

But echo of $today (last row in code) is

Today: 2014-10-19

So, what is wrong? Last $date in function is "2014-10-20" and this value is returning to $today, but $today shows different value. Any idea?

The function is strictly speaking recursive, but you never assign the return value of the inner call to anything. — kojiro
– kojiro, Commented Oct 15, 2014 at 18:38
That code is hideously inefficient. You're doing repeated roundtrips from string->timestamp->string on every single call. Why don't you just pass the timestamp around and almost all of those strtotime calls? — Marc B
– Marc B, Commented Oct 15, 2014 at 18:52

andy · Accepted Answer · 2014-10-15 18:42:38Z

1

As kojiro pointed out in the comment, you do not assign the return value of the inner call to todayDate(). To change this, replace this line

todayDate($date);

with

$date = todayDate($date);

answered Oct 15, 2014 at 18:42

andy

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3 Comments

SilentCry Over a year ago

It works :-) I tought that function goes in this way todayDate(2014-10-18) > if > date+1 = 2014-10-19 > todayDate(2014-10-19) > if > date+1 = 2014-10-20 > todayDate(2014-10-20) > else > return --> last date value was 2014-10-20. $date = todayDate($date) goes out of my head, but important is, that it works. Thank you!

andy Over a year ago

You should familiarize yourself with the concept of function return values. Recursive functions can lead to complicated errors.

SilentCry Over a year ago

Oh, today I looked at this function and ... I have it :-D Thanks

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