Running a Perl Program: Guide for Students

Summary

Perl is a programming language. Students learn how to write, run and debug Perl programs.

Running Perl

Use a text editor to write a Perl program. Make the file executable and run it. If errors occur, use warnings or a debugger to find them.

Subroutines and parameters

Subroutines are functions in Perl. They can be placed anywhere but are usually grouped. Parameters are passed as a list to the special @_ array.

Returning values and conditionals

A subroutine's result is its last evaluated value. Conditional statements can have multiple alternatives, using elsif with an 'e' missing.

Text file exercises

Students are given exercises to alter a program. It should count lines with certain strings, using the $_ variable and word boundaries.

Key terms

Subroutines

Functions that users define in Perl programs.

Special variables

Variables with odd names that have specific uses in Perl.

@_ array

The list array variable that holds parameters passed to a subroutine.

Regular expressions

Patterns used to match strings in Perl, also for substitutions.

Associative array

A Perl data structure that stores key-value pairs.

Environment variables

Variables set when running a Perl program, stored in the %ENV array.

Questions this document helps with

• How do you run a Perl program from the command line?
• How can you pass parameters to a Perl subroutine?
• What is the difference between elsif and else in Perl?

Summary written with AI from the document's text.