best method to stop users posting urls

Question

I am looking to implement a system to strip out url's from text posted by a user.

I know there is no perfect solution and users will still attempt things like:

www dot google dot com

so I know that ultimately any solution will be flawed in some way... all I am looking to do really is reduce the number of people doing it.

Any suggestions, source or approaches appriciated,

Thanks

Answer 1

You need to define exactly what you want to strip out. The stricter the definition, the more false positives you will get. The following example will remove any string with 3 characters, followed by a period, more letters, another period and 2-4 more letters:

$text = preg_replace('/[a-z]{3}\.[a-z]+\.[a-z]{2,4}/i', '', $text);

The other end of strictness might be anything that ends on a period and 2-4 letters (like .com):

$text = preg_replace('/[a-z]+\.[a-z]{2,4}/i', '', $text);

Note that the latter will strip out the last word of a sentence, the full stop and the first word of the next sentence if someone forgets to add a space inbetween the sentences.

Answer 2

There are number of regular expression pattern matchers here. Some of them are quite complex. I would suggest that running multiple ones may be a good idea.