Tag Archives: regex

Learning to Use Regular Expressions by Example

Dario F. Gomes

This site I’m working on relies heavily on user input through forms, and all that data needs to be checked before being sent a database. I knew PHP3’s regular expression functions should solve my problem, but I didn’t know how to form the regular expressions in the first place. What I needed were some sample strings–obviously the first places I looked were the PHP3 manual and the POSIX 1002.3 specification, but they don’t help much in the way of exemplifying.
Adding to that, I had a really hard time finding good literature on the Web about the subject. I eventually got to know how to do it, mostly through experimenting, and seeing there wasn’t much to it, I decided to write down this straight-out introduction to the syntax and a step-by-step on building regular expressions to validate money and e-mail address strings. I just hope it manages to clear the fog around the subject for all you fellow programmers.

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