I have some HTML and I want to pull out a list of all the tags present in the code. I was thinking the expression I'd use with sed would be... More on old.reddit.com

Your example sites don't really care about SEO because they're either behind a login or are... well... Google. Checkout something like a recipe site which has to compete much harder on page rank. More on reddit.com

Let's back up a second and figure out what this "exercise" is meant to teach you. Or maybe a better way to think about it is this: what's the most you could get out of this exercise? These are all just educated guesses, my opinion, etc. etc. First, at the most superficial level, it's meant to teach you about string manipulation. You have a set of string-related tools in your toolbox and this is a fine way to practice them. This is fine and very boring. There are also a million ways to do this that don't involve HTML. Remove all numbers from a string. Parse a CSV file. Detect all SSN number inside a string. Blah blah blah. They're worth doing, but they'll get old pretty quick and you'll find yourself either inventing more powerful tools or looking for more powerful tools. If you think this is the only thing you're meant to get out of the exercise you'll only get 5% of what you could. :) Second, you have to get comfortable understanding a document format defined by a third-party — HTML in this case. How well do you know it, really? Have you ever read the specifications? Do you know how to read the specifications? The ability to read technical documentation is valuable in general, not just in this case, so that's something worth learning. For example, you'd learn that there are multiple versions of HTML. Does your "HTML scrubber" work for all of them? Does it need to? How can you verify that it works for all of them? Third, if you do read the HTML spec, you'll see that HTML is actually quite complicated. For example, this is perfectly valid HTML: Hey, buddy! Can your "HTML scrubber" handle that? Does it need to? That example isn't even that pathological, but it gives you a sense of where a naïve "HTML scrubber" might mess up. What other pathological cases can you find? Do you need to handle them all? If you decide you want to handle them all, how do you know you've found "all" the pathological cases? Suddenly the problem is much less cut-and-dry and becomes more conversational. It's no longer this binary "do I scrub HTML or not" but instead is a question of scope: do I need to scrub all HTML? Are there situations where it'd be really important that I do scrub it all? Are there situations where I can ignore some pathological cases and perhaps make my code much simpler as a result? You'll learn a lot by trying to scrub HTML using only those methods. You should see how far you can take it. Here's the twist ending, though: there's no way to properly scrub HTML in the way you describe that isn't tantamount to implementing a full-blown HTML parser. HTML is not a nice, neat language. There's a field in computer science called Formal Language Theory which enables us to make precise statements about (1) what a language is and (2) how "nice and neat" it is. There's a class of formal languages called "regular languages" which are precisely the languages that can be parsed, verified, or generated using regular expressions. Bad news: HTML is not a regular language. This means that even if you bring the full power of regular expressions to bear on this problem you will still not be able to do it. If you want to do well on this problem, think about it this way. Talk about these issues, your understanding of them, and really grapple with the problems at hand. Don't just check the checkbox, hand in the homework, and fool yourself into thinking you "know how to scrub HTML" or that you're "really learning how to program." If you do this for every CS homework exercise you have for the rest of the year you'll come out the other end Knowing Your Shit™. :) More on reddit.com

Awesome.

Anything similar for CSS?

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