in reply to Working on a file.

Or have a look at DBI and DBD::CSV. It allows you to access your file as a database and use SQL to get your answers.

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James