imptortance of reguler expression.?

Question

COMPUTERS

Answer 1

At this point, mostly historical and theoretical.

Early on, when memories were very small and processors slow, the fact that regular expressions can be parsed by a finite state automata (constant memory, processing time proportional to the length of the string) was critical and is still extremely convenient (and heavily used by editors, text processing languages, etc.)

http://en.wikipedia.org/wiki/Chomsky_hierarchy