Beginning Perl

Curtis "Ovid" Poe has specialized in Perl since 2000. He is an author, a regular guest speaker at conferences across Europe and the United States, and he wrote the test harness that currently ships with the Perl language. Wrox Beginning guides are crafted to make learning programming languages and technologies easier than you think, providing a structured, tutorial format that will guide you through all the techniques involved.

INTRODUCTION xxiii

CHAPTER 1: WHAT IS PERL? 1

Perl Today 2

Getting Perl 3

Working with Non-Windows Platforms: perlbrew 4

Using Windows 6

The Perl Community 8

IRC 8

PerlMonks 9

Perl Mongers 9

StackOverflow 9

Using perldoc 11

Understanding the Structure of perldoc 11

Getting Started with perldoc 11

Using Tutorials and FAQs 12

Using the perldoc -f function 14

Using a Terminal Window 14

Using the Command Line 15

Creating a Work Directory 16

Creating Hello, World! 18

Writing Your First Program 18

Shebang Lines 21

Summary 22

CHAPTER 2: UNDERSTANDING THE CPAN 25

CPAN and METACPAN 26

Finding and Evaluating Modules 27

Downloading and Installing 29

CPAN Clients 33

Using the CPAN.pm Client 33

Using the Cpanm Client 35

PPM 36

CPAN::Mini 36

Summary 39

CHAPTER 3: VARIABLES 41

What Is Programming? 42

A Few Things to Note Before Getting Started 43

strict, warnings, and diagnostics 43

The my Function 43

Sigils 44

Identifiers 45

Scalars 46

Strings 47

Numbers 51

Arrays 53

Breaking Down the Code 54

Accessing Elements 55

Iterating over Arrays 58

Hashes 58

Accessing Elements 59

Iterating Over Hashes 60

Adding Data to Hashes 60

Slices 61

Array Slices 62

Hash Slices 62

Context 63

Scalar Context 63

List Context 64

Scope 67

my Variables 67

Package Variables 69

Strict, Warnings, and Diagnostics 72

strict 74

warnings 74

diagnostics 75

Working Without a Net 76

Perl’s Built-in Variables 78

$_ 78

%ENV 79

@ARGV 79

Other Special Variables 80

Summary 81

CHAPTER 4: WORKING WITH DATA 83

Using Scalars 84

Working with Strings 85

Using String Operators 94

Scalar::Util 97

Numeric Builtins 98

Bitwise Operators 103

Understanding Booleans 103

Assignment Operators 108

Precedence and Associativity 109

Array and List Functions 111

Built-in Array Functions 111

List::Util 116

Built-in Hash Functions 116

delete() 116

exists() 117

keys() 117

values() 117

each() 117

Scoping Keywords 119

my() 119

local() 119

our() 120

state() 120

Summary 121

CHAPTER 5: CONTROL FLOW 125

Using the if Statement 126

Understanding Basic Conditionals 126

else/elsif/unless 128

The Ternary Operator ?: 131

for/foreach loops 132

Arrays 132

Lists 135

C-Style 136

Using while/until Loops 142

Lists 143

last/next/redo/continue 144

Labels 146

Statement Modifiers 147

Types of Statement Modifiers 147

do while/do until 149

given/when 151...