G'day rahul02,

This is an inappropriate way to ask a question here. You should know this from your last (and only other) post, "Perl Script for reading a mathematical expression", which contained just:

"i want to know the basic idea for writing a perl script which will read a mathematical expression from user, evaluate the result and print on the screen."

I suggest you read both "How do I post a question effectively?" and "How (Not) To Ask A Question".

"perlintro -- a brief introduction and overview of Perl" should provide the basics you need; follow the links provided for more detailed information on the topics of interest (e.g. Files and I/O).

Use Text::CSV (or one of its related modules) for your CSV work.