Learning Perl by Schwartz, Randal L. -- Read -- Imperial Library of Trantor

Index

Learning Perl

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Typographical Conventions Code Examples Safari® Books Online How to Contact Us History of This Book Changes from the Previous Edition Acknowledgments

From Randal From Tom From brian From All of Us

1. Introduction

Questions and Answers

Is This the Right Book for You? Why Are There So Many Footnotes? What About the Exercises and Their Answers? What Do Those Numbers Mean at the Start of the Exercise? What If I’m a Perl Course Instructor?

What Does “Perl” Stand For?

Why Did Larry Create Perl? Why Didn’t Larry Just Use Some Other Language? Is Perl Easy or Hard? How Did Perl Get to Be So Popular? What’s Happening with Perl Now? What’s Perl Really Good For? What Is Perl Not Good For?

How Can I Get Perl?

What Is CPAN? How Can I Get Support for Perl? Are There Any Other Kinds of Support? What If I Find a Bug in Perl?

How Do I Make a Perl Program?

A Simple Program What’s Inside That Program? How Do I Compile My Perl Program?

A Whirlwind Tour of Perl Exercises

2. Scalar Data

Numbers

All Numbers Have the Same Format Internally Floating-Point Literals Integer Literals Nondecimal Integer Literals Numeric Operators

Strings

Single-Quoted String Literals Double-Quoted String Literals String Operators Automatic Conversion Between Numbers and Strings

Perl’s Built-in Warnings Scalar Variables

Choosing Good Variable Names Scalar Assignment Binary Assignment Operators

Output with print

Interpolation of Scalar Variables into Strings Creating Characters by Code Point Operator Precedence and Associativity Comparison Operators

The if Control Structure

Boolean Values

Getting User Input The chomp Operator The while Control Structure The undef Value The defined Function Exercises

3. Lists and Arrays

Accessing Elements of an Array Special Array Indices List Literals

The qw Shortcut

List Assignment

The pop and push Operators The shift and unshift Operators The splice Operator

Interpolating Arrays into Strings The foreach Control Structure

Perl’s Favorite Default: $_ The reverse Operator The sort Operator The each Operator

Scalar and List Context

Using List-Producing Expressions in Scalar Context Using Scalar-Producing Expressions in List Context Forcing Scalar Context

<STDIN> in List Context Exercises

4. Subroutines

Defining a Subroutine Invoking a Subroutine Return Values Arguments Private Variables in Subroutines Variable-Length Parameter Lists

A Better &max Routine Empty Parameter Lists

Notes on Lexical (my) Variables The use strict Pragma The return Operator

Omitting the Ampersand

Non-Scalar Return Values Persistent, Private Variables Exercises

5. Input and Output

Input from Standard Input Input from the Diamond Operator The Invocation Arguments Output to Standard Output Formatted Output with printf

Arrays and printf

Filehandles Opening a Filehandle

Binmoding Filehandles Bad Filehandles Closing a Filehandle

Fatal Errors with die

Warning Messages with warn Automatically die-ing

Using Filehandles

Changing the Default Output Filehandle

Reopening a Standard Filehandle Output with say Filehandles in a Scalar Exercises

6. Hashes

What Is a Hash?

Why Use a Hash?

Hash Element Access

The Hash As a Whole Hash Assignment The Big Arrow

Hash Functions

The keys and values Functions The each Function

Typical Use of a Hash

The exists Function The delete Function Hash Element Interpolation

The %ENV hash Exercises

7. In the World of Regular Expressions

What Are Regular Expressions? Using Simple Patterns

Unicode Properties About Metacharacters Simple Quantifiers Grouping in Patterns Alternatives

Character Classes

Character Class Shortcuts Negating the Shortcuts

Exercises

8. Matching with Regular Expressions

Matches with m// Match Modifiers

Case-Insensitive Matching with /i Matching Any Character with /s Adding Whitespace with /x Combining Option Modifiers Choosing a Character Interpretation Other Options

Anchors

Word Anchors

The Binding Operator =~ Interpolating into Patterns The Match Variables

The Persistence of Captures Noncapturing Parentheses Named Captures The Automatic Match Variables

General Quantifiers Precedence

Examples of Precedence And There’s More

A Pattern Test Program Exercises

9. Processing Text with Regular Expressions

Substitutions with s///

Global Replacements with /g Different Delimiters Substitution Modifiers The Binding Operator Nondestructive Substitutions Case Shifting

The split Operator The join Function m// in List Context More Powerful Regular Expressions

Nongreedy Quantifiers Matching Multiple-Line Text Updating Many Files In-Place Editing from the Command Line

Exercises

10. More Control Structures

The unless Control Structure

The else Clause with unless

The until Control Structure Expression Modifiers The Naked Block Control Structure The elsif Clause Autoincrement and Autodecrement

The Value of Autoincrement

The for Control Structure

The Secret Connection Between foreach and for

Loop Controls

The last Operator The next Operator The redo Operator Labeled Blocks

The Conditional Operator ?: Logical Operators

The Value of a Short Circuit Operator The defined-or Operator Control Structures Using Partial-Evaluation Operators

Exercises

11. Perl Modules

Finding Modules Installing Modules

Using Your Own Directories

Using Simple Modules

The File::Basename Module Using Only Some Functions from a Module The File::Spec Module Path::Class CGI.pm Databases and DBI Dates and Times

Exercises

12. File Tests

File Test Operators

Testing Several Attributes of the Same File Stacked File Test Operators

The stat and lstat Functions The localtime Function Bitwise Operators

Using Bitstrings

Exercises

13. Directory Operations

Moving Around the Directory Tree Globbing An Alternate Syntax for Globbing Directory Handles Recursive Directory Listing Manipulating Files and Directories Removing Files Renaming Files Links and Files Making and Removing Directories Modifying Permissions Changing Ownership Changing Timestamps Exercises

14. Strings and Sorting

Finding a Substring with index Manipulating a Substring with substr Formatting Data with sprintf

Using sprintf with “Money Numbers” Interpreting Non-Decimal Numerals

Advanced Sorting

Sorting a Hash by Value Sorting by Multiple Keys

Exercises

15. Smart Matching and given-when

The Smart Match Operator Smart Match Precedence The given Statement

Dumb Matching

Using when with Many Items Exercises

16. Process Management

The system Function

Avoiding the Shell

The Environment Variables The exec Function Using Backquotes to Capture Output

Using Backquotes in a List Context

External Processes with IPC::System::Simple Processes as Filehandles Getting Down and Dirty with Fork Sending and Receiving Signals Exercises

17. Some Advanced Perl Techniques

Slices

Array Slice Hash Slice

Trapping Errors

Using eval More Advanced Error Handling autodie

Picking Items from a List with grep Transforming Items from a List with map Fancier List Utilities Exercises

A. Exercise Answers

Answers to Chapter 1 Exercises Answers to Chapter 2 Exercises Answers to Chapter 3 Exercises Answers to Chapter 4 Exercises Answers to Chapter 5 Exercises Answers to Chapter 6 Exercises Answers to Chapter 7 Exercises Answers to Chapter 8 Exercises Answers to Chapter 9 Exercises Answers to Chapter 10 Exercises Answer to Chapter 11 Exercises Answers to Chapter 12 Exercises Answers to Chapter 13 Exercises Answers to Chapter 14 Exercises Answers to Chapter 15 Exercises Answers to Chapter 16 Exercises Answer to Chapter 17 Exercises

B. Beyond the Llama

Further Documentation Regular Expressions Packages Extending Perl’s Functionality

Libraries Writing Your Own Modules

Databases

Direct System Database Access Flat-File Database Access

Other Operators and Functions

Transliteration with tr/// Here Documents

Mathematics

Advanced Math Functions Imaginary and Complex Numbers Large and High-Precision Numbers

Lists and Arrays

map and grep

Bits and Pieces Formats Networking and IPC

System V IPC Sockets

Security Debugging Command-Line Options Built-in Variables Syntax Extensions References

Complex Data Structures Object-Oriented Programming Anonymous Subroutines and Closures

Tied Variables Operator Overloading Dynamic Loading Embedding Converting Other Languages to Perl Converting find Command Lines to Perl Command-Line Options in Your Programs Embedded Documentation More Ways to Open Filehandles Threads and Forking Graphical User Interfaces (GUIs) And More…

C. A Unicode Primer

Unicode UTF-8 and Friends Getting Everyone to Agree Fancy Characters

Fancier Characters

Dealing with Unicode in Perl

Using Unicode in Your Source Fancier Characters by Name Reading from STDIN or Writing to STDOUT or STDERR Reading from and Writing to Files Dealing with Command-Line Arguments Dealing with Databases