scheme is an alternative recording of the same information. This is used to overcome the usability
issues presented by CAPTCHA.
As a more simple but effective example, in the following exercise you create a small library that asks
simple math questions with random operands. Call it
Start off by installing a required external library. Numbers_Words is a PEAR library that trans-
forms numbers to words, and you’re using it to make it harder for an automated script to parse
your forms and calculate the results. The official page of the package is
PEAR offers a simple installation script. Open a command-line editor in the folder that contains
. If you’re using XAMPP as instructed in Chapter 1, the folder will be
. To browse to that folder using a command-line console, type this command:
cd \Program Files\xampp\php
At this moment your command-line console will look as shown in Figure 8-10.
To install the Numbers_Words package, you need to execute this command:
pear install Numbers_Words
If the Numbers_Words package hasn’t reached a stable version (as is the case at the moment of
writing this chapter), you need to explicitly mention the beta version that you want to install,
pear install channel://pear.php.net/Numbers_Words-0.15.0
You should get a package confirmation message such as the following:
>pear install channel://pear.php.net/Numbers_Words-0.15.0
downloading Numbers_Words-0.15.0.tgz ...
Starting to download Numbers_Words-0.15.0.tgz (44,854 bytes)
............done: 44,854 bytes
install ok: channel://pear.php.net/Numbers_Words-0.15.0
At this point you can close the command-line console.
Chapter 8: Black Hat SEO
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