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Perl Online tutorial

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CONTENTS

  At a Glance

• Where You're Going

Chapter 1   Getting Started

• What Is Perl?
• How Do I Find Perl?
  • Where Do I Get Perl?
  • Other Places to Get Perl
• A Sample Perl Program
• Running a Perl Program
  • If Something Goes Wrong
• The First Line of Your Perl Program: How Comments Work
  • Comments
• Line 2: Statements, Tokens, and <STDIN>
  • Statements and Tokens
  • Tokens and White Space
  • What the Tokens Do: Reading from Standard Input
• Line 3: Writing to Standard Output
  • Function Invocations and Arguments
• Error Messages
• Interpretive Languages Versus Compiled Languages
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 2   Basic Operators and Control Flow

• Storing in Scalar Variables Assignment
  • The Definition of a Scalar Variable
  • Scalar Variable Syntax
  • Assigning a Value to a Scalar Variable
• Performing Arithmetic
  • Example of Miles-to-Kilometers Conversion
  • The chop Library Function
• Expressions
  • Assignments and Expressions
• Other Perl Operators
• Introduction to Conditional Statements
• The if Statement
  • The Conditional Expression
  • The Statement Block
  • Testing for Equality Using ==
  • Other Comparison Operators
• Two-Way Branching Using if and else
• Multi-Way Branching Using elsif
• Writing Loops Using the while Statement
• Nesting Conditional Statements
• Looping Using the until Statement
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 3   Understanding Scalar Values

• What Is a Scalar Value?
• Integer Scalar Values
  • Integer Scalar Value Limitations
• Floating-Point Scalar Values
  • Floating-Point Arithmetic and Round-Off Error
• Using Octal and Hexadecimal Notation
  • Decimal Notation
  • Octal Notation
  • Hexadecimal Notation
  • Why Bother?
• Character Strings
  • Using Double-Quoted Strings
  • Escape Sequences
  • Single-Quoted Strings
• Interchangeability of Strings and Numeric Values
  • Initial Values of Scalar Variables
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 4   More Operators

• Using the Arithmetic Operators
  • Exponentiation
  • The Remainder Operator
  • Unary Negation
• Using Comparison Operators
  • Integer-Comparison Operators
  • String-Comparison Operators
  • String Comparison Versus Integer Comparison
  • Comparison and Floating-Point Numbers
• Using Logical Operators
  • Evaluation Within Logical Operators
  • Logical Operators as Subexpressions
• Using Bit-Manipulation Operators
  • What Bits Are and How They Are Used
  • The Bit-Manipulation Operators
• Using the Assignment Operators
  • Assignment Operators as Subexpressions
• Using Autoincrement and Autodecrement
  • The Autoincrement Operator Pre-Increment
  • The Autoincrement Operator Post-Increment
  • The Autodecrement Operator
  • Using Autoincrement With Strings
• The String Concatenation and Repetition Operators
  • The String-Concatenation Operator
  • The String-Repetition Operator
  • Concatenation and Assignment
• Other Perl Operators
  • The Comma Operator
  • The Conditional Operator
• The Order of Operations
  • Precedence
  • Associativity
  • Forcing Precedence Using Parentheses
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 5   Lists and Array Variables

• Introducing Lists
• Scalar Variables and Lists
  • Lists and String Substitution
• Storing Lists in Array Variables
• Accessing an Element of an Array Variable
  • More Details on Array Element Names
• Using Lists and Arrays in Perl Programs
  • Using Brackets and Substituting for Variables
• Using List Ranges
  • Expressions and List Ranges
• More on Assignment and Array Variables
  • Copying from One Array Variable to Another
  • Using Array Variables in Lists
  • Substituting for Array Variables in Strings
  • Assigning to Scalar Variables from Array Variables
• Retrieving the Length of a List
• Using Array Slices
  • Using List Ranges in Array-Slice Subscripts
  • Using Variables in Array-Slice Subscripts
  • Assigning to Array Slices
  • Overlapping Array Slices
  • Using the Array-Slice Notation as a Shorthand
• Reading an Array from the Standard Input File
• Array Library Functions
  • Sorting a List or Array Variable
  • Reversing a List or Array Variable
  • Using chop on Array Variables
  • Creating a Single String from a List
  • Splitting a String into a List
  • Other List-Manipulation Functions
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 6   Reading from and Writing to Files

• Opening a File
  • The File Variable
  • The Filename
  • The File Mode
  • Checking Whether the Open Succeeded
• Reading from a File
  • File Variables and the Standard Input File
  • Terminating a Program Using die
  • Reading into Array Variables
• Writing to a File
  • The Standard Output File Variable
  • Merging Two Files into One
• Redirecting Standard Input and Standard Output
• The Standard Error File
• Closing a File
• Determining the Status of a File
  • File-Test Operator Syntax
  • Available File-Test Operators
  • More on the -e Operator
  • Testing for Read Permission-the -r Operator
  • Checking for Other Permissions
  • Checking for Empty Files
  • Using File-Test Operators with File Variables
• Reading from a Sequence of Files
  • Reading into an Array Variable
• Using Command-Line Arguments as Values
  • ARGV and the <> Operator
• Opening Pipes
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 7   Pattern Matching

• Introduction
• The Match Operators
  • Match-Operator Precedence
• Special Characters in Patterns
  • The + Character
  • The [] Special Characters
  • The * and ? Special Characters
  • Escape Sequences for Special Characters
  • Matching Any Letter or Number
  • Anchoring Patterns
  • Variable Substitution in Patterns
  • Excluding Alternatives
  • Character-Range Escape Sequences
  • Matching Any Character
  • Matching a Specified Number of Occurrences
  • Specifying Choices
  • Reusing Portions of Patterns
  • Pattern-Sequence Scalar Variables
  • Special-Character Precedence
  • Specifying a Different Pattern Delimiter
• Pattern-Matching Options
  • Matching All Possible Patterns
  • Ignoring Case
  • Treating the String as Multiple Lines
  • Evaluating a Pattern Only Once
  • Treating the String as a Single Line
  • Using White Space in Patterns
• The Substitution Operator
  • Using Pattern-Sequence Variables in Substitutions
  • Options for the Substitution Operator
  • Evaluating a Pattern Only Once
  • Treating the String as Single or Multiple Lines
  • Using White Space in Patterns
  • Specifying a Different Delimiter
• The Translation Operator
  • Options for the Translation Operator
• Extended Pattern-Matching
  • Parenthesizing Without Saving in Memory
  • Embedding Pattern Options
  • Positive and Negative Look-Ahead
  • Pattern Comments
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

In Review   In Review

Week 2   Week 2 at a Glance

• Where You're Going

Chapter 8   More Control Structures

• Using Single-Line Conditional Statements
  • Problems with Single-Line Conditional Statements
• Looping Using the for Statement
  • Using the Comma Operator in a for Statement
• Looping Through a List: The foreach Statement
  • The foreach Local Variable
  • Changing the Value of the Local Variable
  • Using Returned Lists in the foreach Statement
• The do Statement
• Exiting a Loop Using the last Statement
• Using next to Start the Next Iteration of a Loop
• The redo Statement
• Using Labeled Blocks for Multilevel Jumps
  • Using next and redo with Labels
• The continue Block
• The goto Statement
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 9   Using Subroutines

• What Is a Subroutine?
• Defining and Invoking a Subroutine
  • Forward References to Subroutines
• Returning a Value from a Subroutine
  • Return Values and Conditional Expressions
• The return Statement
• Using Local Variables in Subroutines
  • Initializing Local Variables
• Passing Values to a Subroutine
  • Passing a List to a Subroutine
• Calling Subroutines from Other Subroutines
• Recursive Subroutines
• Passing Arrays by Name Using Aliases
• Using the do Statement with Subroutines
• Specifying the Sort Order
• Predefined Subroutines
  • Creating Startup Code Using BEGIN
  • Creating Termination Code Using END
  • Handling Non-Existent Subroutines Using AUTOLOAD
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 10   Associative Arrays

• Limitations of Array Variables
• Definition
• Referring to Associative Array Elements
• Adding Elements to an Associative Array
• Creating Associative Arrays
• Copying Associative Arrays from Array Variables
• Adding and Deleting Array Elements
• Listing Array Indexes and Values
• Looping Using an Associative Array
• Creating Data Structures Using Associative Arrays
  • Linked Lists
  • Structures
  • Trees
  • Databases
  • Example: A Calculator Program
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 11   Formatting Your Output

• Defining a Print Format
• Displaying a Print Format
• Displaying Values in a Print Format
  • Creating a General-Purpose Print Format
  • Choosing a Value-Field Format
  • Printing Value-Field Characters
  • Using the Multiline Field Format
• Writing to Other Output Files
  • Saving the Default File Variable
• Specifying a Page Header
  • Changing the Header Print Format
• Setting the Page Length
  • Using print with Pagination
• Formatting Long Character Strings
  • Eliminating Blank Lines When Formatting
  • Supplying an Indefinite Number of Lines
• Formatting Output Using printf
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 12   Working with the File System

• File Input and Output Functions
  • Basic Input and Output Functions
  • Skipping and Rereading Data
  • System Read and Write Functions
  • Reading Characters Using getc
  • Reading a Binary File Using binmode
• Directory-Manipulation Functions
  • The mkdir Function
  • The chdir Function
  • The opendir Function
  • The closedir Function
  • The readdir Function
  • The telldir and seekdir Functions
  • The rewinddir Function
  • The rmdir Function
• File-Attribute Functions
  • File-Relocation Functions
  • Link and Symbolic Link Functions
  • File-Permission Functions
  • Miscellaneous Attribute Functions
• Using DBM Files
  • The dbmopen Function
  • The dbmclose Function
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 13   Process, String, and Mathematical Functions

• Process- and Program-Manipulation Functions
  • Starting a Process
  • Terminating a Program or Process
  • Execution Control Functions
  • Miscellaneous Control Functions
• Mathematical Functions
  • The sin and cos Functions
  • The atan2 Function
  • The sqrt Function
  • The exp Function
  • The log Function
  • The abs Function
  • The rand and srand Functions
• String-Manipulation Functions
  • The index Function
  • The rindex Function
  • The length Function
  • Retrieving String Length Using tr
  • The pos Function
  • The substr Function
  • The study Function
  • Case Conversion Functions
  • The quotemeta Function
  • The join Function
  • The sprintf Function
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 14   Scalar-Conversion and List-Manipulation Functions

• The chop Function
• The chomp Function
• The crypt Function
• The hex Function
• The int Function
• The oct Function
  • The oct Function and Hexadecimal Integers
• The ord and chr Functions
• The scalar Function
• The pack Function
  • The pack Function and C Data Types
• The unpack Function
  • Unpacking Strings
  • Skipping Characters When Unpacking
  • The unpack Function and uuencode
• The vec Function
• The defined Function
• The undef Function
• Array and List Functions
  • The grep Function
  • The splice Function
  • The shift Function
  • The unshift Function
  • The push Function
  • The pop Function
  • Creating Stacks and Queues
  • The split Function
  • The sort and reverse Functions
  • The map Function
  • The wantarray Function
• Associative Array Functions
  • The keys Function
  • The values Function
  • The each Function
  • The delete Function
  • The exists Function
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Week 2   Week 2 in Review

Week 3   Week 3 at a Glance

• Where You're Going

Chapter 15   System Functions

• System Library Emulation Functions
  • The getgrent Function
  • The setgrent and endgrent Functions
  • The getgrnam Function
  • The getgrid Function
  • The getnetent Function
  • The getnetbyaddr Function
  • The getnetbyname Function
  • The setnetent and endnetent Functions
  • The gethostbyaddr Function
  • The gethostbyname Function
  • The gethostent, sethostent, and endhostent Functions
  • The getlogin Function
  • The getpgrp and setpgrp Functions
  • The getppid Function
  • The getpwnam Function
  • The getpwuid Function
  • The getpwent Function
  • The setpwent and endpwent Functions
  • The getpriority and setpriority Functions
  • The getprotoent Function
  • The getprotobyname and getprotobynumber Functions
  • The setprotoent and endprotoent Functions
  • The getservent Function
  • The getservbyname and getservbyport Functions
  • The setservent and endservent Functions
  • The chroot Function
  • The ioctl Function
  • The alarm Function
  • Calling the System select Function
  • The dump Function
• Socket-Manipulation Functions
  • The socket Function
  • The bind Function
  • The listen Function
  • The accept Function
  • The connect Function
  • The shutdown Function
  • The socketpair Function
  • The getsockopt and setsockopt Functions
  • The getsockname and getpeername Functions
• The UNIX System V IPC Functions
  • IPC Functions and the require Statement
  • The msgget Function
  • The msgsnd Function
  • The msgrcv Function
  • The msgctl Function
  • The shmget Function
  • The shmwrite Function
  • The shmread Function
  • The shmctl Function
  • The semget Function
  • The semop Function
  • The semctl Function
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 16   Command-Line Options

• Specifying Options
  • Specifying Options on the Command Line
  • Specifying an Option in the Program
• The -v Option: Printing the Perl Version Number
• The -c Option: Checking Your Syntax
• The -w Option: Printing Warnings
  • Checking for Possible Typos
  • Checking for Redefined Subroutines
  • Checking for Incorrect Comparison Operators
• The -e Option: Executing a Single-Line Program
• The -s Option: Supplying Your Own Command-Line Options
  • The -s Option and Other Command-Line Arguments
• The -P Option: Using the C Preprocessor
  • The C Preprocessor: A Quick Overview
• The -I Option: Searching for C Include Files
• The -n Option: Operating on Multiple Files
• The -p Option: Operating on Files and Printing
• The -i Option: Editing Files
  • Backing Up Input Files Using the -i Option
• The -a Option: Splitting Lines
• The -F Option: Specifying the Split Pattern
• The -0 Option: Specifying Input End-of-Line
• The -l Option: Specifying Output End-of-Line
• The -x Option: Extracting a Program from a Message
• Miscellaneous Options
  • The -u Option
  • The -U Option
  • The -S Option
  • The -D Option
  • The -T Option: Writing Secure Programs
• The -d Option: Using the Perl Debugger
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 17   System Variables

• Global Scalar Variables
  • The Default Scalar Variable: $_
  • The Program Name: $0
  • The User ID: $< and $>
  • The Group ID: $( and $)
  • The Version Number: $]
  • The Input Line Separator: $/
  • The Output Line Separator: $
  • The Output Field Separator: $,
  • The Array Element Separator: $"
  • The Number Output Format: $#
  • The eval Error Message: $@
  • The System Error Code: $?
  • The System Error Message: $!
  • The Current Line Number: $.
  • Multiline Matching: $*
  • The First Array Subscript: $[
  • Multidimensional Associative Arrays and the $; Variable
  • The Word-Break Specifier: $:
  • The Perl Process ID: $$
  • The Current Filename: $ARGV
  • The Write Accumulator: $^A
  • The Internal Debugging Value: $^D
  • The System File Flag: $^F
  • Controlling File Editing Using $^I
  • The Format Form-Feed Character: $^L
  • Controlling Debugging: $^P
  • The Program Start Time: $^T
  • Suppressing Warning Messages: $^W
  • The $^X Variable
• Pattern System Variables
  • Retrieving Matched Subpatterns
  • Retrieving the Entire Pattern: $&
  • Retrieving the Unmatched Text: the $` and $' Variables
  • The $+ Variable
• File System Variables
  • The Default Print Format: $~
  • Specifying Page Length: $=
  • Lines Remaining on the Page: $-
  • The Page Header Print Format: $^
  • Buffering Output: $|
  • The Current Page Number: $%
• Array System Variables
  • The @_ Variable
  • The @ARGV Variable
  • The @F Variable
  • The @INC Variable
  • The %INC Variable
  • The %ENV Variable
  • The %SIG Variable
• Built-In File Variables
  • STDIN, STDOUT, and STDERR
  • ARGV
  • DATA
  • The Underscore File Variable
• Specifying System Variable Names as Words
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 18   References in Perl 5

• Introduction to References
• Using References
• Using the Backslash Operator
• References and Arrays
• Multidimensional Arrays
• References to Subroutines
  • Using Subroutine Templates
• Using Subroutines to Work with Multiple Arrays
  • Pass By Value or By Reference?
• References to File Handles
  • What Does the *variable Operator Do?
• Using Symbolic References… Again
  • Declaring Variables with Curly Braces
• More on Hard Versus Symbolic References
• For More Information
• Summary
• Q&A
• Workshop
  • Quiz
• Exercises

Chapter 19   Object-Oriented Programming in Perl

• An Introduction to Modules
  • The Three Important Rules
• Classes in Perl
• Creating a Class
• Blessing a Constructor
  • Instance Variables
• Methods
• Exporting Methods
• Invoking Methods
• Overrides
• Destructors
• Inheritance
• Overriding Methods
• A Few Comments About Classes and Objects in Perl
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 20   Miscellaneous Features of Perl

• The require Function
  • The require Function and Subroutine Libraries
  • Using require to Specify a Perl Version
• The $#array Variables
  • Controlling Array Length Using $#array
• Alternative String Delimiters
  • Defining Strings Using <<
• Special Internal Values
• Using Back Quotes to Invoke System Commands
• Pattern Matching Using ?? and the reset Function
  • Using reset with Variables
• Other Features of the <> Operator
  • Scalar Variable Substitution and <>
  • Creating a List of Filenames
• Global Indirect References and Aliases
• Packages
  • Defining a Package
  • Switching Between Packages
  • The main Package
  • Referring to One Package from Another
  • Specifying No Current Package
  • Packages and Subroutines
  • Defining Private Data Using Packages
  • Packages and System Variables
  • Accessing Symbol Tables
• Modules
  • Creating a Module
  • Importing Modules Into Your Program
  • Using Predefined Modules
• Using Perl in C Programs
• Perl and CGI Scripts
• Translators and Other Supplied Code
• Summary
• Q&A
• Workshop
  • Quiz
  • Exercises

Chapter 21   The Perl Debugger

• Entering and Exiting the Perl Debugger
  • Entering the Debugger
  • Exiting the Debugger
• Listing Your Program
  • The l command
  • The - Command
  • The w Command
  • The // and ?? Commands
  • The S Command
• Stepping Through Programs
  • The s Command
  • The n Command
  • The f command
  • The Carriage-Return Command
  • The r Command
• Displaying Variable Values
  • The X Command
  • The V Command
• Breakpoints
  • The b Command
  • The c Command
  • The L Command and Breakpoints
  • The d and D Commands
• Tracing Program Execution
• Line Actions
  • The a Command
  • The A Command
  • The < and > Commands
  • Displaying Line Actions Using the L Command
• Other Debugging Commands
  • Executing Other Perl Statements
  • The H Command: Listing Preceding Commands
  • The ! Command: Executing Previous Commands
  • The T Command: Stack Tracing
  • The p Command: Printing an Expression
  • The = Command: Defining Aliases
  • Predefining Aliases
  • The h Command: Debugger Help
• Summary
• Q&A
• Workshop
  • Quiz

Week 3   Week 3 in Review

Appendix A   Answers

• Answers for Chapter 1, "Getting Started"
  • Quiz
  • Exercises
• Answers for Chapter 2, "Basic Operators and Control Flow"
  • Quiz
  • Exercises
• Answers for Chapter 3, "Understanding Scalar Values"
  • Quiz
  • Exercises
• Answers for Chapter 4, "More Operators"
  • Quiz
  • Exercises
• Answers for Chapter 5, "Lists and Array Variables"
  • Quiz
  • Exercises
• Answers for Chapter 6, "Reading from and Writing to Files"
  • Quiz
  • Exercises
• Answers for Chapter 7, "Pattern Matching"
  • Quiz
  • Exercises
• Answers for Chapter 8, "More Control Structures"
  • Quiz
  • Exercises
• Answers for Chapter 9, "Using Subroutines"
  • Quiz
  • Exercises
• Answers for Chapter 10, "Associative Arrays"
  • Quiz
  • Exercises
• Answers for Chapter 11, "Formatting Your Output"
  • Quiz
  • Exercises
• Answers for Chapter 12, "Working with the File System"
  • Quiz
  • Exercises
• Answers for Chapter 13, "Process, String, and Mathematical Functions"
  • Quiz
  • Exercises
• Answers for Chapter 14, "Scalar-Conversion and List-Manipulation Functions"
  • Quiz
  • Exercises
• Answers for Chapter 15, "System Functions"
  • Quiz
  • Exercises
• Answers for Chapter 16, "Command-Line Options"
  • Quiz
  • Exercises
• Answers for Chapter 17, "System Variables"
  • Quiz
  • Exercises
• Answers for Chapter 18, "References in
  Perl 5"
  • Quiz
  • Exercises
• Answers for Chapter 19, "Object-Oriented Programming in Perl"
  • Quiz
  • Exercises
• Answers for Chapter 20, "Miscellaneous Features of Perl"
  • Quiz
  • Exercises
• Answers for Chapter 21, "The Perl Debugger"
  • Quiz

Appendix B   ASCII Character Set

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