--#-- Wha'd I say? --#-- One reason Perl has become so universal in CGI programming for the Web is its flexible and powerful regular expression parsing.

Here's an example that probably cannot be duplicated by any other language in as few lines of code.

Let's say you need to stuff a user's data from a Web form back into the HTML form's fields. Why would you want to do this? Maybe you're displaying a "Confirm" page at the end of a lengthy, multi-page form. You want the user not only to confirm the data, but be able to change it if necessary.

Or, and too few Web sites do this, you're correcting a user's input. She entered digits in a name, or left a required-field blank. Ordinarily, what most sites do is put up an "Error" page and tell the user to go back and fix the error. If you rely on the browser's "Back" button to take them back, you're operating on blind faith that the data will still be available in the browser's cache. If not, well... too bad.

Much better to re-populate the fields programatically with your CGI script. To do this, you'll need a good set of regexes. And here they are ...