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Regular Expressions can be very useful tools for web developers. However, they can be a bit tricky to use, especially when you are not very experienced in web or software development. Well, over at Cats who Code they have put together a list of 15 useful regular expressions for web developers. The code is written in PHP, but should be fairly easy to translate to other languages.

Below is an excerpt from the post.

For many beginners, regular expressions seems to be hard to learn and use. In fact, they're far less hard than you may think. Before we dive deep inside regexp with useful and reusable codes, let's quickly see the basics:

Regular expressions syntax

Regular Expression	Will match...
foo	The string "foo"
^foo	"foo" at the start of a string
foo$	"foo" at the end of a string
^foo$	"foo" when it is alone on a string
[abc]	a, b, or c
[a-z]	Any lowercase letter
[^A-Z]	Any character that is not a uppercase letter
(gif|jpg)	Matches either "gif" or "jpeg"
[a-z]+	One or more lowercase letters
[0-9.-]	?ny number, dot, or minus sign
^[a-zA-Z0-9_]{1,}$	Any word of at least one letter, number or _
([wx])([yz])	wy, wz, xy, or xz
[^A-Za-z0-9]	Any symbol (not a number or a letter)
([A-Z]{3}|[0-9]{4})	Matches three letters or four numbers

 

PHP regular expression functions

Function	Description
preg_match()	The preg_match() function searches string for pattern, returning true if pattern exists, and false otherwise.
preg_match_all()	The preg_match_all() function matches all occurrences of pattern in string.
preg_replace()	The preg_replace() function operates just like ereg_replace(), except that regular expressions can be used in the pattern and replacement input parameters.
preg_split()	The preg_split() function operates exactly like split(), except that regular expressions are accepted as input parameters for pattern.
preg_grep()	The preg_grep() function searches all elements of input_array, returning all elements matching the regexp pattern.
preg_ quote()	Quote regular expression characters

You can read the full post here.