However, the version you are reading here is as the author originally submitted the article for publication, not after their editors applied their creativity. Please read all the information in the table of contents before using this article. One of Perl's many strengths is its ability to easily manipulate text strings. Hopefully, in the next few paragraphs, I'll bring the art of regular expressions out into the light. A regular expression is nothing more than a template that selects a class of strings that match, distinguishing them from a class of strings that don't match.
Regular expressions can do more than simply check for an exact matching substring.
Often, they contain wildcard constructs. These wildcard constructs allow the regular expression to match any of a possible list of characters in a particular position. Character classes are enclosed in square brackets. Character classes can describe what you don't want to match, as well as what you do want to match, simply by including a up-arrow as the first character within the brackets. Even with characters and character classes, you still aren't matching things of varying lengths.