Archive for June, 2012

Possibly the most malicious Regular Expression

This is the next of my episode on regular expressions. Today, we look at the worst regex you can possibly come up with, although it looks innocent and simple. You will learn about this backtracking trap that let’s you easily wait for 10^30 steps, as an example of an errant email regex will illustrate. One possible solution we investigate is the use of possessive quantifiers.

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