Get Array values from Recursive function using php

Question

I am trying to find out the parents of a new member till root. For this, I have written a recursive function in PHP that is expected to work, but results are not as expected.

$parlist=array();
function parlistf($child, $con, &$parlist)
{
 $qry="SELECT par from users where sno='$child'";
 $res=$con->query($qry);
 $row=$res->fetch_object();
 if($row->par>0)
 {
 echo "<br>-----<br>$row->par<br>-----<br>";
 $parlist[] = parlistf($row->par, $con, $parlist);;
 var_dump($parlist);
 }
}
parlistf($newid, $con, $parlist);
echo "<br>";
var_dump($parlist);

Result of above code is as under:

-----
15
-----
-----
7
-----
-----
3
-----
-----
1
-----
array(1) { [0]=> NULL } array(2) { [0]=> NULL [1]=> NULL } array(3) { [0]=> NULL [1]=> NULL [2]=> NULL } array(4) { [0]=> NULL [1]=> NULL [2]=> NULL [3]=> NULL } array(4) { [0]=> NULL [1]=> NULL [2]=> NULL [3]=> NULL }

As your can see here, echo is working fine but values are not stored in the array. Where I am doing wrong?

• NappingRabbit: $parlist[] = parlistf($row->par, $con, $parlist);; has two ; and I dont see what return it is feeding the array.
• ArtisticPhoenix: @NappingRabbit - pass by reference. &$parlist

Answer 1

Try this:

$parlist[] = $row->par;
parlistf($row->par, $con, $parlist);

instead of this:

$parlist[] = parlistf($row->par, $con, $parlist);

Your line feeds $parlist with the not existing return value of the function.

• ITSagar: I forgot a column in sql query: SELECT par, lvl from users where sno='$child' How can I store both as pair in associative array?
• marcus.kreusch: Depending on what output you need, it could be $parlist[$row->par] = $row->lvl; or $parlist[] = [$row->par=>$row->lvl]
• ITSagar: var_dump($parlist); now shows: array(4) { [0]=> array(1) { [15]=> int(3) } [1]=> array(1) { [7]=> int(2) } [2]=> array(1) { [3]=> int(1) } [3]=> array(1) { [1]=> int(0) } } But, looping as: foreach($parlist AS $id=>$xlvl) { $elvl=$lvl-$xlvl; } says: Fatal error: Unsupported operand types
• marcus.kreusch: $xlvl contains an array in your example
• ITSagar: if this right approach: for($i=0; $i<count($parlist); $i++) { foreach($parlist[$i] as $id=>$xlvl) { $elvl=$lvl-$xlvl;}}