Regular Expresion

Regular Expression (RegEx) is an implementation of the pattern matching operations (Pattern Recognation) for a text or a string. With regex we can look for text that matches a certain pattern or rule, validating the input data, and others.
Regular Expression consists of a string that is a combination of normal characters, some meta characters and meta sequences. In the implementation of this combination, normal character represents the character itself. While Meta characters and meta sequences are sequences that represent the character or purpose. For example: quantity, location, or type of a particular character.

1. Basic Theory The basic theory of the regex can be brought into any work environment. Regex can be applied to many programming languages??. Starting from Perl, PHP, Python, Java, JavaScript to VB. Not only that it can also be applied to Unix through grep and awk utility, as well as Windows and other OS with a variety of other programs.

For example: regex can be used in a text editor (such as vi and joe), configuration file various daemons and utilities (such as procmail, exim, and Apache), even in applications like Microsoft Word and Borland Delphi were not spared from the use of regex.