Finally we have a Book-Shelf at home and which forces me to arrange all my books properly. While doing that I found one old book ( my favorite ) during my engineering Compiler Design in C. It was week-end so I decided to open and see what is there in the dust. While going through Implementing Thompson’s Construction. I decided to implement the same in C++. Code in the book is very complex to understand. In computing, a regular expression, also referred to as regex or regexp, provides a concise and flexible means for matching strings of text, such as particular characters, words, or patterns of characters. A regular expression is written in a formal language that can be interpreted by a regular expression processor, a program that either serves as a parser generator or examines text and identifies parts that match the provided specification.
A great piece of work is also done on regular expression Here
My code and implementation can be found at Regular Expression library in C++.