University of Washington, CSE 190 M, Spring 2009
Lab 3: PHP (Thursday, April 16)

lab idea and code by Brian Le

The purpose of this lab is to practice using PHP to create dynamic pages. You very likely won't finish all of the exercises. Just finish as much as you can within the allotted time. You do not need to work on this lab any more after you leave your lab session, though you may if you like.

Lab 3 Resources

MP3 Music Library

Brian has written a page named music.html (right-click and select Save Link Target As...) that contains a display of all the MP3s he has on his computer. He has already written the HTML code and the styles for the page, viewer.css. (You don't need to do any CSS for this lab.)


However, the page is not very flexible, because he must manually edit it every time he adds songs to his collection. In this lab, you are to turn this page into a dynamic PHP page in a file named music.php that will list the MP3s and will always display the songs currently on the computer.

Exercises for Today:

  1. Display MP3 Files
  2. Display Playlists
  3. View Songs in a Playlist
  4. Extra Song Info
  5. Shuffle Song Order

Exercise 1: Display MP3 Files (roughly 20 minutes)

The first task is to convert music.html into a PHP page that displays Brian's MP3s. Examine the files in the songs/ folder and display each .mp3 file in the format currently shown in the music.html page. Each one becomes a list item (li) with a class of mp3item. Each song's title should be a link to download that song file from the computer.

Your page should look like this:

expected output

It may help you to remember that the glob and scandir functions list files in a directory, and that the basename function extracts the file name from a larger path string.

You may want to download this list of MP3s and playlist files for testing:

Exercise 2: Display Playlists (roughly 10 minutes)

Brian's music collection also includes playlists, which are text files containing lists of his favorite songs. For this exercise, modify your PHP code to display any playlist files, which are .txt files in the songs/ directory. They should display very similarly to the .mp3 files, except they use a class of playlistitem so that they have a different icon. For now, a playlist's link is the same as an MP3's link: It downloads the file.

Your page should look like this:

expected output

Exercise 3: View Songs in a Playlist (roughly 15 minutes)

Next you should modify the behavior of your page so that it can optionally display just the songs that are listed in a certain playlist. A playlist is just a text file, where each line of the file contains the file name of an MP3 that is part of the playlist. For example, the file songs/mypicks.txt has the following contents:

Be More.mp3
Just Because.mp3
Drift Away.mp3

For this exercise, change your PHP code so that if your page is given a query parameter of playlist, it will read the playlist text file with the given name and display its songs only. For example, if your page is displayed with the following URL:


Then your page should look like this:

expected output

You may assume that any songs contained in a playlist actually do exist on the computer.

Recall that query parameters are put into a global PHP array named $_REQUEST. To access the above query parameter, you should write a line of code such as the following:

$playlist = $_REQUEST["playlist"];

If no query parameter is given, your page should use its previous behavior, displaying all .mp3 and .txt files. You can test whether a particular parameter has been passed by calling PHP's isset function.

Exercise 4: Song Size Info (roughly 10 minutes)

If you have time, add some information to the end of each song shown on the page. Display the song's size in the appropriate unit. If the song is 0 to 1023 bytes in size, display it as bytes. If it is 1024 to 1048575 bytes in size, display it as kilobytes (multiples of 1024 bytes). If it is 1048576 or more bytes, display it as megabytes (multiples of 1048576 bytes).

If displaying kb or mb, you should round your value to the nearest hundredth. You may want to review the documentation for the round function.

Your page should look like this:

expected output

Exercise 5 (for 1337 h4x0rz only): Extra Features

If you finish all of the above exercises, you can try adding any of the following optional extra features to your page: