Like the Short Answer question, the RegExp Short Answer question expects the student to answer an "open" question with a word or a short phrase. However, using so-called regular expressions gives you access to a more powerful system for analysing the student's answers and thus providing more adapted feedback messages. Make sure you download the version of REGEXP that corresponds to your Moodle version.
Download for Moodle 1.9 available (see link below).
Download for Moodle 2.0 available (see link below).
Download for Moodle 2.1.2 moved to the new Moodle plugins repository here.
If you want to integrate RegExp questions in your Cloze (multianswer) questions you'll have to upload one or two replacement files in your <moodle>question/type/multianswer/ folder.
For Moodle 1.9
Download modified question/type/multianswer/questiontype.php for moodle 1.9
For Moodle 2.0.
Download modified question/type/multianswer/questiontype.php for moodle 2.0
For Moodle 2.1
If you need to use REGEXP inside a CLOZE question type, you'll have to replace 2 files in your current moodle 2.1 question/type/multianswer/ folder:
renderer.php and questiontype.php
You can find those modified files here on my github:
To see RegExp (for moodle 1.9 only) in action, go to http://rezeau.info/moodle and login to Demo course as student1, password Student1!
For a teacher access, e-mail me at firstname.lastname@example.org.