September 2012
Beginner
744 pages
15h 48m
English
Content preview from Beginning PerlBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Chapter 10
sort, map, and grep
WHAT YOU WILL LEARN IN THIS CHAPTER:
- Sorting lists alphabetically and numerically
- Creating custom sorts with sort subroutines
- Using map and grep to efficiently transform and filter lists and avoiding their traps
- Combing map, sort, and grep to create powerful list manipulations
WROX.COM CODE DOWNLOAD FOR THIS CHAPTER
The wrox.com code downloads for this chapter are found at http://www.wrox.com/remtitle.cgi?isbn=1118013847 on the Download Code tab. The code for this chapter is divided into the following major examples:
- example_10_1_soldier.pl
- example_10_2_is_prime.pl
- example_10_3_celsius.pl
- listing_10_1_employee.pl
- listing_10_2_collate.pl
- listing_10_3_locale_sort.pl
By this time in the book you should have a sufficient understanding of Perl that you’re able to use it for small tasks in relation to your day-to-day work. However, there’s an odd sort of “litmus test” for Perl developers. For some reason, understanding sort, map, and grep seems to be the difference between beginner and intermediate Perl developers. When you cross this threshold, you’re well on your way to being a Perl expert.
Though sort, map, and grep have been mentioned briefly, their usage has deliberately been kept simple. Now you can see a bit more about their full power.
The one thing to remember is that each of these creates a new list from an old list.
BASIC SORTING
The sort builtin sorts a list and returns a new list. It has three forms:
sort LIST sort BLOCK LIST sort SUBNAME ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.