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• ↓ Complete Regular Expressions Tutorial
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"A regular expression (regex or regexp for short) is a special text string for describing a search pattern. You can think of regular expressions as wildcards on steroids. You are probably familiar with wildcard notations such as *.txt to find all text files in a file manager. The regex equivalent is ^.*\.txt$."

"But you can do much more with regular expressions. In a text editor like EditPad Pro or a specialized text processing tool like PowerGREP, you could use the regular expression \b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}\b to search for an email address. Any email address, to be exact. A very similar regular expression (replace the first \b with ^ and the last one with $) can be used by a programmer to check whether the user entered a properly formatted email address. In just one line of code, whether that code is written in Perl, PHP, Java, a .NET language, or a multitude of other languages."

"If you just want to get your feet wet with regular expressions, take a look at the one-page regular expressions quick start. While you can’t learn to efficiently use regular expressions from this brief overview, it’s enough to be able to throw together a bunch of simple regular expressions. Each section in the quick start links directly to detailed information in the tutorial."

"Do not worry if the above example or the quick start make little sense to you. Any non-trivial regex looks daunting to anybody not familiar with them. But with just a bit of experience, you will soon be able to craft your own regular expressions like you have never done anything else. The free Regular-Expressions.info Tutorial explains everything bit by bit."

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Complete Regular Expressions Tutorial

Applications & Languages That Support Regexes

Not Only for Programmers

Ad-Free Access and Printable PDF Download