- 01Setting up (what you'll need)
- 02Your first output (print)
- 03Variables (scalar variables, $)
- 04Branching (the if statement)
- 05Repeating (the for loop)
- 06Writing a subroutine (a function)
- 07Repeating (the while loop)
- 08Working with arrays (@)
- 09Working with hashes (%)
- 10Regular expression matching
- 11Substitution with regular expressions (s///)
- 12Working with strings
- 13References
- 14Anonymous subroutines
- 15File input and output, the basics
- 16Modules and use strict / warnings
- 17The ternary operator
- 18Sorting (sort)
- 19Packages and the basics of object orientation
- 20[Project] Build a small inventory system
Modules and use strict / warnings
This lesson covers use strict; use warnings; — which belongs in every piece of Perl — along with how to use a module.
use strict; forbids things such as using a variable without my, and use warnings; reports suspicious code. Putting both at the top of a Perl program is treated as all but mandatory.
The sample code declares use strict; use warnings;, loads the sum function from the standard List::Util module with use List::Util qw(sum);, and totals an array.
A common early stumble is skipping these declarations. The code still runs without them, but typos and similar bugs become much harder to notice, so writing them every time is strongly recommended.
In professional work, the convention is so well established that Perl code without use strict; use warnings; gets flagged in review.
๐งช This site can't compile or run Perl directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser โ nothing is sent anywhere).