PHP illegal offset type error - php

Question

Getting an illegal offset type error on this line in the second foreach loop.
$userlist[$user]->addPeriod($period);
Made some changes from past info given in past threads and this is the new version of the code. There is also a warning but I think that might be resolved if the error is resolved:
Call to a member function addPeriod() on a non-object
$periods_arr = array(1, 2, 3, 4, 5);
$subPeriods_arr = array(1, 2);
$questionslist = array("q_1_1", "q_1_2", "q_2_1", "q_2_2", "q_3_1", "q_4_1", "q_5_1");
class User {
public $userId;
public $periods = array();
public function __construct($number)
{
$this->userId = $number;
}
public function addPeriod($pno)
{
$this->periods[] = new Period($pno);
}
}
class Period {
public $periodNo;
public $subPeriods = array();
public function __construct($number)
{
$this->periodNo = $number;
}
public function addSubPeriod($spno)
{
$this->subPeriods[] = new SubPeriod($spno);
}
}
class SubPeriod {
public $SubPeriodNo;
public $answers = array();
public function __construct($number)
{
$this->SubPeriodNo = $number;
}
public function addAnswer($answer)
{
$this->answers[] = new Question($answer);
}
}
class Question {
public $answer;
public function __construct($ans)
{
$this->answer = $ans;
}
public function getAnswer()
{
echo $answer;
}
}
$userlist = array();
$sql = 'SELECT user_ref FROM _survey_1_as GROUP BY user_ref ORDER BY user_ref ASC';
$result = mysql_query($sql);
while ($row = mysql_fetch_array($result))
{
$userlist[] = new User($row['user_ref']);
}
foreach ($userlist as &$user)
{
foreach ($periods_arr as &$period)
{
$userlist[$user]->addPeriod($period);
foreach ($subPeriods_arr as &$subPeriod)
{
$userlist[$user]->periods[$period]->addSubPeriod($subPeriod);
foreach($questionslist as &$aquestion)
{
$sql = 'SELECT ' . $aquestion . ' FROM _survey_1_as WHERE user_ref = ' .
$user . ' AND answer_sub_period = ' . $subPeriod . ' AND answer_period = ' . $period .'';
$result = mysql_query($sql);
while ($row = mysql_fetch_array($result))
{
$userlist[$user]->periods[$period]->subPeriods[$subPeriod]->addAnswer($row[$questionNumber]);
}
}
}
}
}
$userlist[3]->periods[3]->subPeriods[1]->getAnswer();

Answer 1

You're using $user as a key into your $userlist array, but you're fetching it as a value. Try something like this:
foreach ($userlist as $user => $userVal)
{
...
$userlist[$user]->addPeriod($period);
}
This makes $user the key into your $userlist array.
It would be even clearer to do something like this:
foreach ($userlist as $user)
{
}
And then don't use $user as a key into your array, but just use $user as the value. For example:
$user->addPeriod($period);
...
$user->periods[$period]->addSubPeriod($subPeriod);