Sams Teach Yourself Perl in 21 Days, Second Edition

Day 11. Creating and Using Subroutines

We'll finish up your lesson on the core of the Perl language today with a discussion of subroutines, functions, and local variables. With subroutines you can collect bits of commonly used code into a single operation, and then perform that operation at different times in your script—the same way you use the built-in Perl functions.

The specific things you'll learn about include

• The differences between user-defined subroutines and Perl's standard functions

• How to define and call simple subroutines

• Using variables local to subroutine definitions

• Returning values from subroutines

• Passing arguments to subroutines

• Using subroutines in different contexts