PHP - returning variable producing weird outcome

Question

I'm having a weird issue where echo'ing variables is working but $str .= is producing strange outcomes.

    function displayComments($comments, $str){
        foreach ($comments as $info) {
            $str .= $info['id'];
            if (!empty($info['childs'])) {
                $this->displayComments($info['childs'],$str);
            }
        }
        return $str;
       }

     $comments = $this->produceComments($id);
            if(!$comments){
                $str ='
                    <tr>
                        <td>There are no comments for this Project</td>
                    </tr>';
            }else{
                $str = $this->displayComments($comments,'');        
            }

echo $str;

This echos 1,2,3.

The Correct output is 1,2,5,6,3,4 which is output when using

foreach ($comments as $info) {
                echo $info['id'];

Next I tried building with $str .= and echoing the function

function displayComments($comments,$str=FALSE){
    foreach ($comments as $info) {
        $str .= $info['id'];
        if (!empty($info['childs'])) {
            $this->displayComments($info['childs']);
        }
    }
    echo $str;
    return $str;
  }

This produces 5,6,4,1,2,3 which is out of order and weird.. and when also echo'ed outside of the function it produces 1,2,3 Why does echo'ing the $info['id'] output correctly, but building the values into $str not work and also returning $str cuts values out.

Also why does echo'ing inside the function with $str produce a different combination inside the function as opposed to outside after a return.

The array

dave · Accepted Answer · 2014-02-03 03:11:36Z

1

I'm pretty sure

foreach ($comments as $info) {
        $str .= $info['id'];
        if (!empty($info['childs'])) {
            $this->displayComments($info['childs'],$str);
        }
    }

should be

foreach ($comments as $info) {
        $str .= $info['id'];
        if (!empty($info['childs'])) {
            $str = $this->displayComments($info['childs'],$str);
        }
    }

You are using recursion, but once you actually recurse, you aren't doing anything with the return data, so it's as if it never happened.

answered Feb 3, 2014 at 3:11

dave

65.1k6 gold badges81 silver badges98 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Chizzle Over a year ago

That's what I thought when I saw this as well. If you are going to build the $str string, define it OUTSIDE of the method being called and only append to it. On the first example there is a '$str =' which is probably causing the weird behavior.

Gregws Over a year ago

That was exactly the issue. Thanks very much Dave.

Collectives™ on Stack Overflow

PHP - returning variable producing weird outcome

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related