Adding an item to an associative array

before for loop :

$data = array();

then in your loop:

$data[] = array($catagory => $question);

I think you want $data[$category] = $question;

Or in case you want an array that maps categories to array of questions:

$data = array();
foreach($file_data as $value) {
    list($category, $question) = explode('|', $value, 2);

    if(!isset($data[$category])) {
        $data[$category] = array();
    }
    $data[$category][] = $question;
}
print_r($data);

You can simply do this

$data += array($category => $question);

If your're running on php 5.4+

$data += [$category => $question];

I know this is an old question but you can use:

array_push($data, array($category => $question));

This will push the array onto the end of your current array. Or if you are just trying to add single values to the end of your array, not more arrays then you can use this:

array_push($data,$question);