Arrays Make My Brain Hurt!

[mistyd]

Arrrrggggh!

I sm so confused by arrays and subarrays. Here's what I am ATTEMPTING to do.

A cable signup form for students.

A student logs in through AD and user info is passed on to our form ... the form performs a find for the user from the user table (if they have had or presently have service with us) or creates a new user. Then it looks for any services that user may presently have for the UserSvcs table, still using the user id for lookup.

I am TRYING to make the form display an add button if they DO NOT presently have the service, or a remove button if they do.

I just can't figure out how to create and pull from the array(s) I need to make this happen. Also, there is one item where that same number could be listed more than once (AddtlBox), as a student can have 3 boxes. Those come back with a serial number to distinguish them.

Can some kind soul point me in the right direction or give me a couple examples to play with?

[ixalmida]

It was hard to wrap my brain around arrays at first, and I still occasionally become perplexed at the best way to structure an array, but you do get used to them.

The easiest type of array to work with is an associative array, where you have a key name and a value:

$student['name'] = "John Smith";

This array is geared towards storing various information about a single student. Since you need to store information about multiple students, you need to add a dimension to the array:

// Manually populate array...
$student[]['name'] = "John Smith";
$student[]['name'] = "Joe Black";

// Cycle through array...
foreach($student as $key => $info)
  {
  // Display values...
  echo $info['$name']."\n";
  }
/*
Will display:
John Smith
Joe Black
*/

So what do you do when one piece of information has three different aspects to it? You add another dimension at the end:

  // Manually populate array...
$student[1]['name'] = "John Smith";
$student[1]['favorites']['color'] = "green";
$student[1]['favorites']['food'] = "pizza";
$student[1]['favorites']['show'] = "Hell's Kitchen";

$student[2]['name'] = "Joe Black";
$student[2]['favorites']['color'] = "blue";
$student[2]['favorites']['food'] = "cheesecake";
$student[2]['favorites']['show'] = "House";

// Cycle through array...
foreach($student as $key => $info)
  {
  // Display name part...
  echo $info['$name']."\n";

  // Cycle through and display "favorites" sub-array...
  foreach($info['favorites'] as $key => $value)
    echo "  Favorite $key: $value\n";
  }
/*
Will display:
John Smith
  Favorite color: green
  Favorite food: pizza
  Favorite show: Hell's Kitchen
Joe Black
  Favorite color: blue
  Favorite food: cheesecake
  Favorite show: House
*/

Typically, you'd populate your arrays from a database, of course, but the principal is the same. Usually, I'll try to use the fields from my database as keys just to keep things consistent.

/* POPULATE ARRAY FROM DATABASE */
// Pull names from database...
$name_result = mysql_query("SELECT student_id, name FROM Students");
$x = 1;

// Populate array of names...
while($names = mysql_fetch_assoc($name_result))
  {
  $student[$x] = $names['name'];

  // Pull favorites from database...
  $fav_result = mysql_query("SELECT fav_type, fav FROM Favorites WHERE student_id = $student_id");

  // Populate array of favorites...
  while($favs = mysql_fetch_assoc($fav_result))
    {
    $fav_type = $favs['fav_type'];
    $student[$x][$fav_type] = $favs['fav'];
    }
  $x++;
  }

Does that help?

[mistyd]

Thank you much ... very nicely put. I will practice with that!