PHP unshif and push value based on current array keys - php

Question

I have a quiz where you can use text field or radio buttons for the answers. The answers are stored in a database. None of the answers are required so people can skip questions.
Each entry is stored in a row:
Array
(
[0] => Array
(
[0] => Dave
[1] => ok
[2] => Manchester
[3] => No
)
[1] => Array
(
[0] => James
[1] => Happy
[2] => London
[3] => Yes
)
[2] => Array
(
[0] => Victoia
[2] => Leeds
)
)
Currently the question number is represented by the key. So Victoria hasn't answered question 1 or 3. My aim is to add the unanswered into the array witht the correct key value being null.
Here is my code so far but I'm struggling to get the array key position correct:
$answersArr = (array) $answers;
$row = array();
$items = array();
$numberOfQuesitons = count($headers);
foreach ($answersArr as $key=>$result) {
$answer = json_decode(stripslashes($result->answers));
$row[$key] = (array) $answer;
$single = count($row[$key]);
$currentKey = key($row[$key]);
for ($i = $single ; $i < $numberOfQuesitons; $i++) {
if ($numberOfQuesitons - $i > 0) {
if ($currentKey > 0) {
array_unshift($row[$key], null);
} else {
array_push($row[$key], null);
}
}
}
}
print_r($row);
The out put I get:
Array
(
[0] => Array
(
[0] => Admin
[1] => ok
[2] => Manchester
[3] => No
)
[1] => Array
(
[0] => Rod
[1] => Happy
[2] => London
[3] => Yes
)
[2] => Array
(
[0] => Rozi
[2] => Leeds
[3] =>
[4] =>
)
)
The last row in the array needs to look like this:
[2] => Array
(
[0] => Victoia
[1] =>
[2] => Somewhere
[3] =>
)
A little stuck here any help would be much appreciated.
Thanks

Answer 1

Let me say that I read through your code and have to make two assumptions: $numberOfQuesitons = 4 and $single = 2 in the case of Victoia.
Assumption is based on the fact that the name of a person is included in the result arrays and otherwise could not be derived.
So in your code at the iteration of Victoia we will have the following array to work with:
$row[$key] = [
0 => 'Victoia',
2 => 'Leeds',
];
Then at the inner for loop the following will happen (as noted in comments):
for ($i = $single; $i < $numberOfQuesitons; $i++) {
// 4 - 2 = 2, 2 > 0 = true <-- first iteration
// 4 - 3 = 1, 1 > 0 = true <-- second (and final) iteration
if ($numberOfQuesitons - $i > 0) {
// $currentKey doesn't change in this process
// and since the key is taken from the array
// $row[$key] points to, the key function will return 0 each iteration.
if ($currentKey > 0) {
// Also note that unshift will only add elements to the front of the array.
array_unshift($row[$key], null);
} else {
// Hence we drop down in this branch of the if statemtent
// as 0 > 0 evaluates to false each evaluation.
// So we start with [0] => Rozi || Victoia
// [2] => Leeds || Somewhere
// Push null thus: [3] => null
// Push null thus: [4] => null
// Hence our final result.
// Also note that push only 'pushes' elements at the end of the array.
array_push($row[$key], null);
}
}
}
To solve this we could change the logic a little bit, but personally I would modify the nested loop to the following (or something similar):
$answersArr = (array) $answers;
$row = array();
$numberOfQuesitons = count($headers);
foreach ($answersArr as $key => $result) {
$answer = json_decode(stripslashes($result->answers));
$row[$key] = (array) $answer;
// We simply create a range from 0 up to the last question number.
$all = range(0, $numberOfQuesitons - 1);
// Taking the difference between all questions and the answered
// ones will give us the missing ones.
$unAnsweredQs = array_diff($all, array_keys($row[$key]));
// Add those missing questions to the array.
foreach ($unAnsweredQs as $unAnswered) {
// Or maybe a more appropriate default.
$row[$key][$unAnswered] = null;
}
// Sort the keys, such that we respect the wanted order
// Name (key 0), Q1, Q2, ..., QN
ksort($row[$key]);
}
print_r($row);