Perl by Example

by Quigley, Ellie

• ISBN13: 9780132381826
• ISBN10: 0132381826
• Edition: 4th
• Format: Paperback
• Copyright: 2007-11-05
• Publisher: Prentice Hall

Summary

"I picked up a copy ofJavaScript by Exampleover the weekend and wanted to thank you for putting out a book that makes JavaScript easy to understand. Irs"ve been a developer for several years now and JS has always been the "monster under the bed," so to speak. Your book has answered a lot of questions Irs"ve had about the inner workings of JS but was afraid to ask. Now all I need is a book that covers Ajax and Coldfusion. Thanks again for putting together an outstanding book." Chris Gomez, Web services manager, Zunch Worldwide, Inc. "I have been reading yourUNIXreg;Shells by Examplebook, and I must say, it is brilliant. Most other books do not cover all the shells, and when you have to constantly work in an organization that uses tcsh, bash, and korn, it can become very difficult. However, your book has been indispensable to me in learning the various shells and the differences between themhellip;so I thought Irs"d email you, just to let you know what a great job you have done!" Farogh-Ahmed Usmani, B.Sc. (Honors), M.Sc., DIC, project consultant (Billing Solutions), Comverse "I have been learning Perl for about two months now; I have a little shell scripting experience but that is it. I first started withLearning Perlby Ors"Reilly. Good book but lacking on the examples. I then went toProgramming Perlby Larry Wall, a great book for intermediate to advanced, didnrs"t help me much beginning Perl. I then picked upPerl by Example, Third Editionthis book is a superb, well-written programming book. I have read many computer books and this definitely ranks in the top two, in my opinion. The examples are excellent. The author shows you the code, the output of each line, and then explains each line in every example." Dan Patterson, software engineer, GuideWorks, LLC "Ellie Quigley has written an outstanding introduction to Perl, which I used to learn the language from scratch. All one has to do is work through her examples, putz around with them, and before long, yours"re relatively proficient at using the language. Even though Irs"ve graduated to usingProgramming Perlby Wall et al., I still find Quigleyrs"s book a most useful reference." Casey Machula, support systems analyst, Northern Arizona University, College of Health and Human Services "When I look at my bookshelf, I see eleven books on Perl programming.Perl by Example, Third Edition,isnrs"t on the shelf; it sits on my desk, where I use it almost daily. When I bought my copy I had not programmed in several years and my programming was mostly in COBOL so I was a rank beginner at Perl. I had at that time purchased several popular books on Perl but nothing that really put it together for me. I am still no pro, but my book has many dog-eared pages and each one is a lesson I have learned and will certainly remember. "I still think it is the best Perl book on the market for anyone from a beginner to a seasoned programmer using Perl almost daily." Bill Maples,

Author Biography

Ellie Quigley has taught scripting languages in Silicon Valley for more than twenty years. Her Perl and shell programming classes at the University of Santa Cruz Extension program have become part of Silicon Valley lore. Her best-selling books include UNIX ® Shells by Example, Fourth Edition; PHP and MySQL by Example (with coauthor Marko Gargenta); and JavaScript by Example, all from Prentice Hall.

Table of Contents

Preface	p. xxvii
The Practical Extraction and Report Language	p. 1
What Is Perl?	p. 1
What Is an Interpreted Language?	p. 2
Who Uses Perl?	p. 3
Where to Get Perl	p. 5
What Is CPAN?	p. 9
Perl Documentation	p. 10
What You Should Know	p. 12
What s Next?	p. 12
Perl Quick Start	p. 13
Quick Start, Quick Reference	p. 13
Chapter Summary	p. 29
What s Next?	p. 29
Perl Scripts	p. 31
Script Setup	p. 31
The Script	p. 32
Perl at the Command Line	p. 39
What You Should Know	p. 43
What s Next?	p. 43
Getting a Handle on Printing	p. 45
The Filehandle	p. 45
Words	p. 45
The print Function	p. 46
The printf Function	p. 59
What You Should Know	p. 66
What s Next?	p. 66
What s in a Name	p. 69
About Perl Variables	p. 69
Scalars, Arrays, and Hashes	p. 77
Reading from STDIN	p. 94
Array Functions	p. 100
Hash (Associative Array) Functions	p. 118
More Hashes	p. 128
What You Should Know	p. 132
What s Next?	p. 133
Where s the Operator?	p. 137
About Perl Operators	p. 137
Mixing Data Types	p. 138
Precedence and Associativity	p. 139
What You Should Know	p. 168
What s Next?	p. 168
If Only, Unconditionally, Forever	p. 171
Control Structures, Blocks, and Compound Statements	p. 171
Repetition with Loops	p. 177
What You Should Know	p. 200
What s Next?	p. 200
Regular ExpressionsPattern Matching	p. 203
What Is a Regular Expression?	p. 203
Expression Modifiers and Simple Statements	p. 204
Regular Expression Operators	p. 210
What You Should Know	p. 232
What s Next?	p. 232
Getting ControlRegular Expression Metacharacters	p. 235
Regular Expression Metacharacters	p. 235
Unicode	p. 281
What You Should Know	p. 283
What s Next?	p. 283
Getting a Handle on Files	p. 285
The User-Defined Filehandle	p. 285
Passing Arguments	p. 310
File Testing	p. 319
What You Should Know	p. 321
What s Next?	p. 322
How Do Subroutines Function?	p. 325
Subroutines/Functions	p. 325
Passing Arguments	p. 330
Call-by-Reference	p. 344
What You Should Know	p. 358
What s Next?	p. 359
Modularize It, Package It, and Send It to the Library!	p. 363
Packages and Modules	p. 363
The Standard Perl Library	p. 370
Modules from CPAN	p. 390
What You Should Know	p. 398
What s Next?	p. 398
Does This Job Require a Reference?	p. 401
What Is a Reference? What Is a Pointer?	p. 401
What You Should Know	p. 420
What s Next?	p. 420
Bless Those Things! (Object-Oriented Perl)	p. 423
The OOP Paradigm	p. 423
Classes, Objects, and Methods	p. 425
Anonymous Subroutines, Closures, and Privacy	p. 453
Inheritance	p. 460
Public User InterfaceDocumenting Classes	p. 474
Using Objects from the Perl Library	p. 479
What You Should Know	p. 484
What s Next?	p. 485
Those Magic Ties and DBM Stuff	p. 493
Tying Variables to a Class	p. 493
DBM Files	p. 505
What You Should Know	p. 512
What s Next?	p. 512
CGI and Perl: The Hyper Dynamic Duo	p. 513
Static and Dynamic Web Pages 513
How It all Works	p. 516
Creating a Web Page with HTML	p. 522
How HTML and CGI Work Together	p. 526
Getting Information Into and Out of the CGI Script	p. 531
CGI and Forms	p. 535
The
Table of Contents provided by Publisher. All Rights Reserved.

Excerpts

You may wonder, why a new edition ofPerl by Example? Perl 5 hasn't really changed that much; in fact, it's changed very little at all since the third edition of this book was published. And since Perl 6 hasn't been officially released, why not wait? Well, consider this. Let's say you bought a new Whirlpool washing machine six years ago. It's running perfectly. But since then, the mounds of laundry washed by that machine have come and gone. Now you're sporting a new trendy fashion, you have designer sheets and towels, and the detergent brand you use is hypoallergenic, nontoxic, and biodegradable, not available when you bought the washer. Even though Perl 5 has changed very little, the computer world has. It is always in a flux of new innovations, technologies, applications, and fads, and programs are being written to accommodate those changes. Whether analyzing data from the GenBank sequence database, writing applications for an iPhone, creating a personal blog on "myspace," or adjusting to the changes in a new Vista version of Windows, some computer program is involved, and very possibly it is a Perl program. Whatever the case, we like to keep up with the times. This new edition ofPerl by Examplewas written for just that purpose. As we speak, I am teaching Perl at the UCSC 1 extension in Sunnyvale, California, to a group of professionals coming from all around the Silicon Valley. I always ask at the beginning of a class, "So why do you want to learn Perl?" The responses vary from, "Our company has an auction site on the Web and I'm the webmaster. I need to use Perl and Apache to process our order information and send it to Oracle," or "I work in a genetics research group at Stanford and have to sift through and analyze masses of data, and I heard that if I learn Perl, I won't have to depend on programmers to do this," or "I'm a UNIX/Linux system administrator and our company has decided that all admin scripts should be converted to Perl," or "I just got laid off and heard that it's an absolute must to have Perl on my resume." And I am always amazed at the variety of people who show up: engineers, scientists, geneticists, meteorologists, managers, salespeople, programmers, techies, hardware guys, students, stockbrokers, administrators of all kinds, librarians, authors, bankers, artistsyou name it. Perl does not exclude anyone. Perl is for everyone and it runs on everything. No matter who you are, I think you'll agree that a picture is worth a thousand words, and so is a good example.Perl by Exampleis organized to teach you Perl from scratch with examples of complete, succinct programs. Each line of a script example is numbered, and important lines are highlighted in bold. The output of the program is then displayed with line numbers corresponding to the script line numbers. Following the output is a separate explanation for each of the numbered lines. The examples are small and to the point for the topic at hand. Since the backbone of this book was used as a student guide to a Perl course, the topics are modularized. Each chapter builds on the previous one with a minimum of forward referencing and a logical progression from one topic to the next. There are exercises at the end of the chapters. You will find all of the examples on the CD at the back of the book. They have been thoroughly tested on a number of major platforms. Perl by Exampleis not just a beginner's guide but a complete guide to Perl. It covers many aspects of what Perl can do, from regular expression handling, to formatting reports, to interprocess communication. It will teach you about Perl and, in the process, a lot about UNIX and Windows. Si