What does this code do?

Question

while (list($task_id, $parent_id, $task) = mysqli_fetch_array($r, MYSQLI_NUM))

Answer 1

It fetches a row (from a MySQL query) into the array with the columns task_id, parent_id, and task until there are no more rows to fetch. The list() function converts these columns into the $task_id, $parent_id, and $task variables for use in the while loop.

In other words: It iterates through a rowset.

Answer 2

http://us3.php.net/manual/en/mysqli-result.fetch-array.php

Just in case you didn't know what mysqli_fetch_array was.

Answer 3

it's a loop through a result set, with a compressed conversion from a mysql result row to individual variables

the long way would be:

while($row=mysqli_fetch_array($result)){
    $task_id   = $row[0];
    $parent_id = $row[1];
    $task      = $row[2];

    // Do something with the row data
}

the relevant pages in the PHP doc are:

Convert an array to a set of variables: http://php.net/list

Fetching a row of a mysqli result object: http://php.net/manual/en/mysqli-result.fetch-array.php