PHP has three sets of functions that allow you to work with regular expressions. Programmer s does not use these powerful functions often as it seems to be difficult to create patterns. Also it is not easy to find a basic and simple regular expression tutorial in a single webpage . So I would like to give a try on this to collect the info and make it easy to learn and interesting. Also I will include some very useful reg-expressions in the end of this post. About regular expressions A regular expression is a pattern that can match various strings. Regular expressions started as a feature of Unix shell. They were made to make string operations easier. It’s really useful in programming with PHP as they help to reduce a lot of codes. As a simple example we can say t...