[solved] Making a parentlist of id

I now have tried this

PHP Code:

public function make_parent_list($fid) {

$sql = "SELECT * FROM forum WHERE fid  = '" . $fid . "'"; 
           
$query = $this->db->query($sql);

$arr = array();
           
foreach ($query->result() as $row) {

if ($row->pid) {

$arr[] = $row->pid;

$arr[] = $this->make_parent_list($row->pid);

}
               
}

return $arr;

} 


But the implode throws error here

Code:

A PHP Error was encountered
Severity: Warning
Message: implode(): Invalid arguments passed
Filename: forums/Forum_management.php

Echo out put is 34,Array

PHP Code:

$results = $this->make_parent_list('36');

foreach ($results as $result) {
echo implode(',', $result);
} 


There's only one rule - please don't tell anyone to go and read the manual.  Sometimes the manual just SUCKS!