PHP - - By Aurelio De Rosa

Easter Eggs: What They Are and How to Create Them

An Easter egg is a hidden message or feature, completely unrelated to normal functionality, that developers put inside software, website, or game. Unlike viruses, worms, and trojans, Easter eggs are completely harmless. They are often used as a sort of signature of a programmer or as a joke. Sometimes they are written by personal initiative of a programmer and not a company request, and in those cases the company might take legal action against the developer. On the other hand, there are plenty of cases where a company, especially ones that specialize in game development, explicitly request several Easter eggs.

A Short History of the Easter Eggs

The term comes from the Anglo-Saxon tradition where parents, hide some eggs in their garden for Easter and then let their children find them. This type of work is often used in games where, for example, through a combination of keys or performing certain actions in a given order, you can access new levels or new powers.

For several years people, myself included, thought that the game Adventure released by Atari in 1979 was the first video game to containing an Easter egg. It wasn’t as amazing as you might think; it just displayed Warren Robinett (the name of the programmer). Although this myth is still alive, it seems that previous Easter eggs existed.

The number of Easter eggs contained in software and games, even the most famous ones, has increased over the last couple decades. The web offers a plethora of examples; companies like Mozilla, Oracle, and Google are just few who have put Easter eggs in their software.

  • Mozilla put an Easter egg in all versions of Firefox. To see it in action, type “about:mozilla” in the address bar and then press enter. Firefox displays a quote from the “Book of Mozilla” about the birth of Firefox.
  • Google created an Easter egg in Picasa. If you open the desktop software and then press Ctrl + Shift + Y, a toy bear image appears. Every time you press the key combination, another bear is displayed.
  • Skype, the famous VoIP software, has a simple but funny example. If you open the chat and then type “(drunk)” a hidden emoticon appears.
  • A Tetris game has been hidden in the uTorrent software. To see it, click the “Help” menu and then go to “About”. Press T key and the game will appear.
  • The OpenOffice suite has a lot of hidden games and other stuff. So many that they have a specific section on their website! If you want to play Tic-Tac-Toe in Calc, write “=GAME(A2:C4;”TicTacToe”)” into the A1 cell and then press enter.

Creating Your First Easter Egg

I’ll guide you in creating a simple Easter egg with PHP. We’ll create a search form, and if a user searches for my name (obviously you can change with your own) the page will show a nice message. This will be the Easter egg.

Create a PHP file with the following HTML code:

<!DOCTYPE html>
<html>
 <head>
  <meta charset="UTF-8">
  <title>My First Easter Egg!</title>
 </head>
 <body>
  <h1>My First Easter Egg!</h1>
  <h2>Search</h2>
  <form method="get" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>">
   <input type="text" name="searched-text" id="searched-text" placeholder="Search..." accesskey="s">
   <input type="submit" value="Search">
  </form>
 </body>
</html>

The form doesn’t have many elements; it only needs an input box where the user can type what she wants to search for and the submit button.

Try to use the form. As you’ll see, it does nothing but redirects the user to the same page, sending what was entered in the search field as a parameter. The business logic has not implemented yet, so don’t worry that nothing special happens.

The next step is to write the business logic. We need to analyze the request using the $_GET superglobal array to see its value. If the searched-text parameter isn’t empty, we’ll display what the user searched for, but in case she searched for my name, I’ll add the funny message “I know, I’m so cool!”.

The resultant code should look as follow.

<?php
if (! empty($_GET['searched-text'])) {
    echo "<h3>You searched for: " . htmlentities($_GET["searched-text"]) . "</h3>";
    // The comparison is case-insensitive
    if (strcasecmp($_GET["searched-text"], "Aurelio De Rosa") == 0) {
        echo "<p>I know, I'm so cool!</p>";
}

Now, when the user searches for my name she’ll see the following screen:

A Slightly More Complicated Example

As you’ve seen, the previous example is very simple. Now I’ll explain a sightly more complicated example. Imagine you have the form, but it’s not very professional to show the message the first time a user searches for your name. Maybe she’s just searching for some software you’ve written. What you can do is to show the funny message only if the user persists in searching repeatedly your name. Ultimately we need a counter and, for the sake of the example, I’ll display the message if the user searches for my name three consecutively times.

The first thing needed is to call session_start(), a function that creates a new session or resumes the current one. Then test if the Easter egg counter is set in the $_SESSION superglobal array; if not, we’ll set its value to zero. Every time the user searches for my name the counter is incremented by 1. In all the other cases, the counter is reset. The last case includes if the message has been displayed too.

The resulting source code is the following:

<?php
session_start();
if (!isset($_SESSION["easter-egg"])) {
    $_SESSION["easter-egg"] = 0;
}
?>
<html>
 <head>
  <meta charset="UTF-8">
  <title>My First Easter Egg!</title>
 </head>
 <body>
  <h1>My First Easter Egg!</h1>
  <h2>Search</h2>
  <form method="get" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>">
   <input type="text" name="searched-text" id="searched-text" placeholder="Search..." accesskey="s">
   <input type="submit" value="Search">
  </form>
<?php
if (!empty($_GET["searched-text"])) {
    echo "<h3>You searched for: " . htmlentities($_GET["searched-text"]) . "</h3>";
    // The comparison is case-insensitive
    if (strcasecmp($_GET["searched-text"], "Aurelio De Rosa") == 0) {
        $_SESSION["easter-egg"]++;
        if ($_SESSION["easter-egg"] == 3) {
            echo "<p>I know, I'm so cool!</p>";
            $_SESSION["easter-egg"] = 0;
        }
    }
    else {
        $_SESSION["easter-egg"] = 0;
    }
}
else {
    $_SESSION["easter-egg"] = 0;
}
?>
 </body>
</html>

Conclusions

I’ve shown you in this article how you can create a simple Easter egg. Easter eggs are a fun way to sign your software and to prove your paternity, Be careful though not to add one in your company software because the consequences could be undesirable. Now, every time you run a new program you’ll probably want search the Internet to see if it contains an Easter egg.

Image via Fotolia

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