We’ve all found useful information on the web. Occassionally, its even
necessary to retrieve that information in an automated fashion. It could be
just for your own amusement, possibly a new web service that hasn’t yet
published an API, or even a critical business partner who only exposes a web
based interface to you.
Of course, screen scraping web pages is not the optimal solution to any
problem, and I highly advise you to look into APIs or formal web services
that will provide a more consistent and intentional programming interface.
Potential problems could arise for a number of reasons.
“Regular Expression” is a fancy way to say “pattern matcher.” Humans
can match patterns with relative ease. A machine has a bit more difficulty
deciphering patterns, especially in text. As computing became more
powerful, the methods for matching text grew into more flexible dialects.
Regular expressions can be one of the toughest concepts to grasp and use
effectively in any programming language. Perl is no exception as its
regular expressions engine is perhaps the most advanced regex engine in
existence. Its power and flexibility also serve to confuse and intimidate
many new comers. It is important to understand the Regular Expression engine
as its often the cause of serious bottlenecks in programs of all shapes and
sizes.