PHP 5 For Dummies

by Janet Valade

PHP 5

FOR

DUMmIES‰

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by Janet Valade

PHP 5

FOR

DUMmIES‰

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PHP 5 For Dummies®

Published by

Wiley Publishing, Inc.

111 River Street

Hoboken, NJ 07030

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Copyright © 2004 by Wiley Publishing, Inc., Indianapolis, Indiana

Published by Wiley Publishing, Inc., Indianapolis, Indiana

Published simultaneously in Canada

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About the Author

Janet Valade is the author of PHP & MySQL For Dummies. In addition, she has

authored and revised chapters for several Linux books and for a Webmaster

certification book.

Janet Valade has 20 years experience in the computing field. She worked as a

Web designer/programmer for an engineering firm. Prior to that, Janet worked

for several years in a university environment as a systems analyst. During her

tenure, she supervised the installation and operation of computing resources,

designed and developed a data archive, provided technical support for faculty

and students, wrote numerous technical papers, and developed and pre￾sented seminars and workshops on a variety of technology topics.

Dedication

This book is dedicated to anyone who finds it useful.

Acknowledgments

I wish to express my appreciation to the entire Open Source community.

Without those who give their time and talent, there would be no cool PHP for

me to write about. Furthermore, I never would have learned this software

without the PHP lists where people generously spend their time answering

foolish questions from beginners. Many ideas have come from reading ques￾tions and answers on the lists.

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Publisher’s Acknowledgments

We’re proud of this book; please send us your comments through our online registration form

located at www.dummies.com/register/.

Some of the people who helped bring this book to market include the following:

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Contents at a Glance

Introduction ................................................................1

Part I: Say Hello to the PHP Scripting Language ...........7

Chapter 1: Getting to Know PHP ......................................................................................9

Chapter 2: Setting Up the Environment ........................................................................19

Chapter 3: Creating Your First PHP Script ....................................................................35

Part II: Variables and Data ........................................51

Chapter 4: Using Variables in PHP Scripts ...................................................................53

Chapter 5: Working with Data ........................................................................................73

Chapter 6: Storing Data in Groups by Using Arrays ....................................................97

Part III: Basic PHP Programming .............................127

Chapter 7: Controlling the Flow of the Script ............................................................129

Chapter 8: Reusing PHP Code ......................................................................................157

Chapter 9: Object-Oriented Programming Meets PHP ..............................................177

Part IV: Common PHP Applications ...........................197

Chapter 10: The Basics of Web Applications .............................................................199

Chapter 11: Other Web Applications ..........................................................................223

Chapter 12: Storing Data with PHP ..............................................................................247

Chapter 13: PHP and Your Operating System ............................................................279

Chapter 14: PHP Extensions .........................................................................................303

Part V: The Part of Tens ...........................................319

Chapter 15: Ten Things to Look For When Troubleshooting a Script ....................321

Chapter 16: Ten PHP Resources You Can’t Live Without .........................................327

Part VI: Appendixes .................................................331

Appendix A: Installing PHP............................................................................................333

Appendix B: Useful PHP Built-in Functions.................................................................353

Index .......................................................................377

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Table of Contents

Introduction .................................................................1

About This Book ..............................................................................................1

How to Use This Book ....................................................................................2

Foolish Assumptions ......................................................................................3

How This Book Is Organized ..........................................................................4

Part I: Say Hello to the PHP Scripting Language ................................4

Part II: Variables and Data ....................................................................4

Part III: Basic PHP Programming .........................................................4

Part IV: Common PHP Applications ....................................................4

Part V: The Part of Tens ........................................................................5

Part VI: Appendixes ...............................................................................5

Icons Used in This Book .................................................................................5

Part I: Say Hello to the PHP Scripting Language ............7

Chapter 1: Getting to Know PHP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Getting Familiar with PHP ..............................................................................9

Considering the Various Uses for PHP .......................................................10

Using PHP for Web applications ........................................................11

Using PHP for database applications ................................................12

Using PHP with your file system .......................................................13

Using PHP for system commands .....................................................13

Understanding How PHP Works ..................................................................14

PHP as a general-purpose language ..................................................14

PHP for the Web ...................................................................................15

Keeping Up with Changes in PHP ................................................................16

PHP 5 .....................................................................................................17

Previous versions of PHP ...................................................................18

Chapter 2: Setting Up the Environment . . . . . . . . . . . . . . . . . . . . . . . . . .19

Establishing Your Web Environment ..........................................................19

Using an existing Web environment ..................................................21

Choosing a Web hosting company ....................................................22

Setting up your own Web environment ............................................25

Testing PHP ..........................................................................................27

Setting Up PHP for General-Purpose Scripting ..........................................30

Configuring PHP ............................................................................................32

Using Tools to Build PHP Scripts ................................................................32

Programming editors ..........................................................................32

Integrated Development Environment (IDE) ...................................33

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Chapter 3: Creating Your First PHP Script . . . . . . . . . . . . . . . . . . . . . . .35

Writing PHP Statements ...............................................................................36

Building Scripts .............................................................................................37

Adding PHP statements to HTML pages ...........................................38

Using PHP independent of the Web ..................................................40

Writing Your First Script ...............................................................................42

Discovering More about Output Statements .............................................44

Processing PHP output statements ...................................................45

Using special characters in output statements ...............................46

Documenting the Script ................................................................................48

Part II: Variables and Data .........................................51

Chapter 4: Using Variables in PHP Scripts . . . . . . . . . . . . . . . . . . . . . .53

Naming Variables ...........................................................................................53

Assigning and Displaying Variable Values ..................................................55

Creating variables ................................................................................55

Displaying variable values .................................................................56

Writing Your First Script That Uses Variables ...........................................57

Discovering More about Output Statements with Variables ...................59

Using Variable Variables ...............................................................................60

Removing Variables ......................................................................................61

Working with Constants ...............................................................................62

Creating constants ..............................................................................62

Understanding when to use constants .............................................63

Displaying constants ...........................................................................66

Utilizing built-in PHP constants .........................................................66

Handling Error Messages .............................................................................67

Changing the error level for your Web site ......................................68

Changing the error level for a script .................................................69

Sending messages to a log ..................................................................70

Advanced error handling ....................................................................70

Chapter 5: Working with Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73

Understanding Data Types ...........................................................................73

Assigning data types ...........................................................................74

Type casting .........................................................................................74

Working with Numbers .................................................................................75

Performing mathematical operations ...............................................75

Formatting numbers for output .........................................................79

Working with Character Strings ..................................................................81

Using special characters in strings ...................................................82

Comparing single-quoted strings and double-quoted strings .......82

Escaping characters ............................................................................84

Joining strings together ......................................................................85

Manipulating strings ...........................................................................85

Formatting output strings ..................................................................89

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Working with Dates and Times ....................................................................92

Formatting dates .................................................................................92

Storing a timestamp in a variable ......................................................94

Chapter 6: Storing Data in Groups by Using Arrays . . . . . . . . . . . . . . .97

Creating and Working with Arrays ..............................................................97

Creating arrays ....................................................................................97

Viewing arrays ...................................................................................100

Modifying arrays ................................................................................101

Removing values from arrays ..........................................................102

Sorting Arrays ..............................................................................................103

Using Arrays in Statements ........................................................................105

Using arrays in echo statements .....................................................106

Using arrays in list statements ........................................................106

Walking through an Array ..........................................................................107

Traversing an array manually ..........................................................108

Using foreach to walk through an array .........................................109

Finding Array Size .......................................................................................110

Converting Arrays into Strings (And Vice Versa) ...................................110

Converting Variables into Arrays (And Vice Versa) ................................112

Splitting and Merging Arrays .....................................................................113

Comparing Arrays .......................................................................................115

Working with Other Array Operations .....................................................116

Summing arrays .................................................................................116

Removing duplicate items ................................................................117

Exchanging keys and values ............................................................117

Multidimensional Arrays ............................................................................118

Creating multidimensional arrays ...................................................119

Viewing multidimensional arrays ....................................................120

Using multidimensional arrays in statements ...............................120

Walking through a multidimensional array ....................................121

Built-in PHP Arrays .....................................................................................123

Using superglobal arrays ..................................................................123

Using $_SERVER and $_ENV .............................................................125

Using $argv and $argc .......................................................................125

Part III: Basic PHP Programming ..............................127

Chapter 7: Controlling the Flow of the Script . . . . . . . . . . . . . . . . . . .129

Changing the Order of Statement Execution ...........................................129

Setting Up Conditions .................................................................................131

Using comparison operators ...........................................................131

Checking variable content ...............................................................133

Pattern matching with regular expressions ...................................133

Joining multiple comparisons ..........................................................138

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Using Conditional Statements ...................................................................140

Using if statements ............................................................................140

Using switch statements ..................................................................144

Repeating Actions by Using Loops ...........................................................145

Using for loops ...................................................................................146

Using while loops ..............................................................................149

Using do..while loops ........................................................................151

Avoiding infinite loops ......................................................................153

Breaking out of a loop .......................................................................154

Chapter 8: Reusing PHP Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157

Inserting Code in Your Script ....................................................................158

Including files .....................................................................................158

Storing include files ...........................................................................160

Setting up include directories ..........................................................161

Creating Reusable Code (Functions) ........................................................162

Defining functions .............................................................................163

Using variables in functions .............................................................165

Passing values to a function ............................................................167

Returning a value from a function ...................................................171

Using built-in functions .....................................................................174

Handling Errors ..........................................................................................174

Chapter 9: Object-Oriented Programming Meets PHP . . . . . . . . . . .177

Introducing Object-Oriented Programming .............................................177

Objects and classes ...........................................................................178

Properties ...........................................................................................179

Methods ..............................................................................................179

Inheritance .........................................................................................180

Object-oriented concepts PHP 5 omits ...........................................180

Developing an Object-Oriented Program .................................................181

Choosing objects ...............................................................................181

Selecting properties and methods for each object .......................182

Creating and using the class ............................................................182

Defining a Class ...........................................................................................183

Writing a class statement .................................................................183

Setting properties ..............................................................................184

Using $this ..........................................................................................185

Adding methods ................................................................................185

Writing the constructor ....................................................................186

Putting it all together ........................................................................187

Using a Class ................................................................................................190

Making Properties and Methods Private ..................................................191

Using Exceptions .........................................................................................194

Copying Objects ..........................................................................................195

Destroying Objects .....................................................................................196

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Part IV: Common PHP Applications ...........................197

Chapter 10: The Basics of Web Applications . . . . . . . . . . . . . . . . . . .199

Securing Your Web Site ...............................................................................200

Ensuring the security of the host computer ..................................200

Keeping information private ............................................................201

Being cautious of information from users ......................................202

Using a secure Web server ...............................................................202

Displaying Static Web Pages ......................................................................203

Working with HTML Forms ........................................................................203

Collecting information from Web site visitors ...............................204

Receiving the information ...............................................................211

Checking the information .................................................................213

Cleaning information .........................................................................220

Chapter 11: Other Web Applications . . . . . . . . . . . . . . . . . . . . . . . . . . .223

Overcoming Statelessness .........................................................................223

Navigating Web Sites with Multiple Pages ...............................................224

Echoing links ......................................................................................224

Using forms ........................................................................................224

Relocating users ................................................................................225

Moving Information from Page to Page ....................................................226

Adding information to the URL ........................................................227

Passing information via cookies ......................................................229

Passing information using HTML forms .........................................231

Using PHP sessions ...........................................................................232

Uploading Files ............................................................................................238

Using a form to upload a file ............................................................239

Accessing information about an uploaded file ..............................240

Moving uploaded files to their destination ....................................241

Putting it all together ........................................................................241

Using JavaScript with PHP .........................................................................244

Adding JavaScript code to a PHP script .........................................244

Using PHP variables with JavaScript ..............................................245

Chapter 12: Storing Data with PHP . . . . . . . . . . . . . . . . . . . . . . . . . . . .247

Using Flat Files .............................................................................................249

Accessing files ...................................................................................249

Writing to a file ...................................................................................252

Reading from a file .............................................................................252

Exchanging data with other programs ...........................................255

Working with Databases .............................................................................259

Understanding database software ..................................................259

Understanding database support in PHP .......................................262

Communicating with your database ...............................................265

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Using PHP with a database ...............................................................266

Handling errors ..................................................................................272

Putting it all together ........................................................................273

Using SQLite .................................................................................................276

Chapter 13: PHP and Your Operating System . . . . . . . . . . . . . . . . . . .279

Managing Files .............................................................................................279

Getting information about files ........................................................280

Copying, renaming, and deleting files .............................................282

Organizing files ..................................................................................283

Using Operating System Commands ........................................................286

Using backticks ..................................................................................288

Using the system function ................................................................289

Using the exec function ....................................................................289

Using the passthru function .............................................................290

Understanding security issues ........................................................291

Using FTP .....................................................................................................292

Logging in to the FTP server ............................................................292

Getting a directory listing ................................................................293

Downloading and uploading files with FTP ....................................294

Other FTP functions ..........................................................................295

Using E-Mail .................................................................................................297

Setting up PHP to send e-mail ..........................................................297

Sending e-mail messages ..................................................................299

Sending e-mail attachments .............................................................300

Chapter 14: PHP Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .303

Investigating the Basic Extensions ...........................................................303

Taking a Look at Standard Extensions ......................................................305

Using PEAR ...................................................................................................309

Finding a PEAR Package ...................................................................309

Setting up PEAR .................................................................................311

Installing a PEAR package ................................................................313

Using a PEAR package .......................................................................314

Part V: The Part of Tens ............................................319

Chapter 15: Ten Things to Look For When

Troubleshooting a Script . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .321

Missing Semicolons .....................................................................................321

Not Enough Equal Signs .............................................................................322

Misspelled Variable Names ........................................................................322

Missing Dollar Signs ....................................................................................323

Troubling Quotes ........................................................................................323

Invisible Output ...........................................................................................324

Numbered Arrays ........................................................................................324

Including PHP Statements ..........................................................................325

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