VISUAL QUICKPRO GUIDE

    PHP 5 ADVANCED

    Larry Ullman

    Peachpit PressVisual QuickPro Guide

    PHP 5 Advanced

    Larry Ullman

    Peachpit Press

    1249 Eighth Street

    Berkeley, CA 94710

    510524-2178

    510524-2221 (fax)

    Find us on the Web at: www.peachpit.com

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    Peachpit Press is a division of Pearson Education.

    Copyright ? 2007 by Larry Ullman

    Editor: Rebecca Gulick

    Copy Editor: Robert Campbell

    Technical Reviewer: Jay Blanchard

    Proofreader: Liz Welch

    Production Coordinator: Becky Winter

    Compositor: Kate Kaminski

    Indexer: Karin Arrigoni

    Cover Design: Peachpit Press

    Notice of Rights

    All rights reserved. No part of this book may be reproduced or transmitted in any form by any

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    The information in this book is distributed on an “As Is” basis, without warranty. While every

    precaution has been taken in the preparation of the book, neither the author nor Peachpit Press

    shall have any liability to any person or entity with respect to any loss or damage caused or

    alleged to be caused directly or indirectly by the instructions contained in this book or by the

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    Visual QuickPro Guide is a registered trademark of Peachpit Press, a division of Pearson

    Education.

    MySQL is a registered trademark of MySQL AB in the United States and in other countries.

    Macintosh and Mac OS X are registered trademarks of Apple Inc. Microsoft, Windows, Windows

    XP, and Windows Vista are registered trademarks of Microsoft Corp. Screenshots of Web sites in

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    claimed as trademarks. Where those designations appear in this book, and Peachpit was aware

    of a trademark claim, the designations appear as requested by the owner of the trademark. All

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    tion with this book.

    ISBN-13: 978-0-321-37601-5 ISBN-10: 0-321-37601-3

    9 8 7 6 5 4 3 2 1

    Printed and bound in the United States of AmericaDedication

    To my good friend Michael K. and his family:

    I cannot thank you all enough for your con-

    tinuing friendship, generosity, and kindness

    over these many years.My utmost thanks to…

    Jessica, the love of my life, for just about

    everything.

    Zoe and Sam, for making my world a

    better place.

    The grandparents, who traveled far and

    often, pitching in with babysitting and

    housework so that I might write this book.

    Everyone at Peachpit Press for their support,for their dedication to putting out quality

    books, and for everything else they do to

    make all this happen.

    The most excellent editor, Rebecca Gulick,for so many reasons.

    Bob Campbell, for his spot-on copy editing

    and attention to detail.

    The production coordinator, Becky Winter,the compositor, Kate Kaminski, the proof-

    reader, Liz Welch, and the indexer, Karin

    Arrigoni, who turn my mess of files into an

    actual book.

    Jay Blanchard, for his technical review.

    The readers, the readers, the readers!Introduction ix

    Chapter 1: Advanced PHP Techniques 1

    Chapter 2: Developing Web Applications 43

    Chapter 3: Advanced Database Concepts 81

    Chapter 4: Security Techniques 123

    Chapter 5: E-commerce Techniques 169

    Chapter 6: Basic Object-Oriented

    Programming 233

    Chapter 7: Advanced OOP 263

    Chapter 8: Real-World OOP 309

    Chapter 9: Networking with PHP 347

    Chapter 10: PHP and the Server 373

    Chapter 11: PHP’s Command-Line Interface 417

    Chapter 12: Using PEAR 443

    Chapter 13: Ajax 481

    Chapter 14: XML and PHP 529

    Index 569

    v

    Contents at a Glance

    Contents at a Glancevi

    Introduction ix

    Chapter 1: Advanced PHP Techniques 1

    Multidimensional Arrays . . . . . 2

    Advanced Function Definitions . . . . 18

    The Heredoc Syntax . . . . . . 31

    Using printf and sprintf . . . . 37

    Chapter 2: Developing Web Applications 43

    Documenting Code . . . . . . 44

    Code Style and Structure . . . . . 47

    Modularizing a Web Site . . . . . 49

    Affecting the Browser Cache . . . . 74

    Chapter 3: Advanced Database Concepts 81

    Storing Sessions in a Database . . . . 82

    Working with U.S. Zip Codes . . . . 96

    Creating Stored Functions . . . . 110

    Displaying Results Horizontally . . . . 116

    Chapter 4: Security Techniques 123

    Remembering the Basics . . . . . 124

    Validating Form Data . . . . . . 126

    Using PECL Filter . . . . . . 136

    Authentication with PEAR Auth . . . 143

    Using MCrypt . . . . . . . 157

    Chapter 5: E-commerce Techniques 169

    E-commerce Concepts . . . . . 170

    Creating the Database . . . . . 171

    Creating the Configuration File . . . . 183

    Making the Template . . . . . . 190

    Creating the Index Page . . . . . 197

    Browsing by Category . . . . . . 199

    Showing a Product . . . . . . 205

    Implementing a Shopping Cart . . . . 212

    Validating Credit Cards . . . . . 224

    Chapter 6: Basic Object-Oriented

    Programming 233

    OOP Theory . . . . . . . 234

    Defining a Class . . . . . . 235

    Creating an Object . . . . . . 240

    The this Attribute . . . . . . 244

    Creating Constructors . . . . . 251

    Creating Destructors . . . . . . 256

    Autoloading Classes . . . . . . 260

    Chapter 7: Advanced OOP 263

    Advanced Theories . . . . . . 264

    Inheriting Classes . . . . . . 266

    Inheriting Constructors and Destructors . . 271

    Overriding Methods . . . . . . 276

    Access Control . . . . . . . 281

    Using the Scope Resolution Operator . . 289

    Creating Static Members . . . . . 294

    Abstract Classes and Methods . . . . 300

    Chapter 8: Real-World OOP 309

    Catching Exceptions . . . . . . 310

    Extending the Exception Class . . . . 317

    Creating a Shopping Cart Class . . . . 328

    Using the Cart Class . . . . . . 340

    Chapter 9: Networking with PHP 347

    Accessing Other Web Sites . . . . 348

    Working with Sockets . . . . . 355

    Performing IP Geolocation . . . . 363

    Using cURL . . . . . . . 368

    Chapter 10: PHP and the Server 373

    Compressing Files . . . . . . 374

    PHP-GTK . . . . . . . . 385

    Establishing a cron . . . . . . 399

    Scheduling Tasks on Windows . . . . 402

    Using COM with PHP . . . . . . 404

    vii

    Chapter 11: PHP’s Command-Line Interface 417

    Testing Your Installation . . . . . 418

    Executing Bits of Code . . . . . 422

    Creating a Command-Line Script . . . 424

    Running a Command-Line Script . . . 428

    Working with Command-Line Arguments . . 432

    Taking Input . . . . . . . 437

    Chapter 12: Using PEAR 443

    Using Benchmark . . . . . . 444

    Using HTML_QuickForm . . . . 456

    Using Mail_Mime . . . . . . 469

    Chapter 13: Ajax 481

    Introduction to Ajax . . . . . . 482

    A Simple Example . . . . . . 484

    Full-Fledged Ajax . . . . . . 506

    Debugging Ajax Applications . . . . 523

    Chapter 14: XML and PHP 529

    What Is XML? . . . . . . . 530

    XML Syntax . . . . . . . 532

    Attributes, Empty Elements, and Entities . . 536

    Document Type Definitions . . . . 540

    Parsing XML . . . . . . . 548

    Creating an RSS Feed . . . . . . 562

    Index 569

    viii

    If you’re looking at this book, then I probably don’t need to tell you how great PHP is.

    Presumably, since you’re perusing the pages of an advanced text on the topic, you are

    already using PHP for developing dynamic Web sites. Maybe you’ve been doing so for

    a couple of years, perhaps just a couple of months. You could have learned PHP on your

    own, in a class, or by reading one of the many excellent books on the subject. (I’m

    referring not just to my own, of course!) Whatever the case, with some experience

    under your belt, you probably don’t want another “here’s how to use PHP and isn’t it

    swell” book. What you probably want to learn is how to use PHP more efficiently, more

    securely, faster, and all-around better than you already are. If so, you’ve found the

    right book.

    In this humble author’s (or not-so-humble author’s) opinion, advanced PHP is about

    learning: how to do different things, how to improve upon the basic things, and about

    technologies that intersect with PHP. In short, you know how to make a dynamic Web

    site with PHP, but you’d like to know how to make a betterWeb site, with every possible

    meaning of “better.” That’s the approach I’ve taken in writing this book. I’ve not set

    out to blow your mind discussing esoteric idiosyncrasies the language has, rewriting

    the PHP, MySQL, or Apache source code, or making theoretically interesting but

    practically useless code. In short, I present to you several hundred pages of beyond-the-

    norm but still absolutely necessary (and often cool) tips and techniques.

    ix

    Introduction

    i

    IntroductionAbout This Book

    Simply put, I’ve tried to make this book’s

    content accessible and useful for every

    PHP programmer out there. As I suggest

    in the introductory paragraphs, I believe

    that “advanced” PHP is mostly a matter

    of extended topics. You already possess

    all the basic knowledge—you retrieve data-

    base query results in your sleep—but want

    to go further. This may mean learning object-

    oriented programming (OOP), using PEAR

    (PHP Extension and Application Repository),incorporating Ajax (Asynchronous JavaScript

    and XML) into a site, or improving upon

    aspects of your existing skill set.

    My definition of advanced PHP program-

    ming covers three loosely grouped skills:

    ◆ Doing what you already do better, faster,and more securely

    ◆ Learning more sophisticated PHP tech-

    niques

    ◆ Doing standard things using PHP and

    other technologies (like PEAR, Ajax,or OOP)

    This book can be divided into three sections,corresponding to those skills. The first five

    chapters cover advanced PHP knowledge

    in general: programming techniques, Web

    applications, databases, security, and e-com-

    merce. They all cover information that the

    average PHP programmer may not be famil-

    iar with but should be able to comprehend,providing useful code in the process.

    The next six chapters focus on extending

    your knowledge to areas of PHP with which

    you might not be as familiar. Half of this sec-

    tion goes over object-oriented programming

    in great detail, from the fundamentals to

    advanced topics to some real-world examples.

    The other three chapters are on different ways

    you might use PHP: to communicate with

    x

    Introduction

    Introductionnetworked servers, to communicate with

    the host server, or from a command-line

    interface. The remaining three chapters each

    deal with a specific technology tied into

    PHP: PEAR, Ajax, and XML.

    Two bonus chapters, “Image Generation” and

    “Creating PDFs”, can be downloaded from

    Peachpit’s Web site. Those two chapters,which are available for free, provide another

    100 pages of content showing how PHP ties

    into related, and very useful, technologies.

    Visit www.peachpit.comtitle0321376013

    to learn how to register this book and

    download the chapters.

    Most examples used in this book are intended

    to be applicable in the real world, omitting

    the frivolous code you might see in other

    books, tutorials, and manuals. I focus as much

    on the philosophies involved as on the coding

    itself so that, in the end, you will come away

    with not just how to do this or that but also

    how to apply the overarching mentality to

    your own, individual projects.

    Unlike with most of my other books, I do

    not expect that you’ll necessarily read this

    book in sequential order, for the most part.

    Some chapters do assume that you’ve read

    others, like the object-oriented ones, which

    have a progression to them. Some later

    chapters also reference examples completed

    in earlier ones. If you read the later ones

    first, you’ll just need to quickly hop over to

    the earlier ones to generate whatever data-

    base or scripts the later chapter requires.

    Finally, I’ll be using XHTML in my scripts

    instead of HTML. I’ll also use some CSS, as

    warranted. I do not discuss either of these

    subjects in this book (and, to be frank, may

    not adhere to them perfectly). If you are not

    already familiar with the subjects, you should

    look at some online resources or good books

    (such as Elizabeth Castro’s excellent Visual

    QuickStart Guides) for more information.

    xi

    Introduction

    IntroductionWhat’s new in this edition

    The most important change in this edition

    of the book is that every bit of code has been

    updated, rewritten, or replaced to ensure

    100 percent compatibility with PHP 5. Many

    of the examples have also been modified

    to take advantage of features added to the

    language.

    What is also new is my approach. The first

    edition of this text was the second book I

    ever wrote. I’ve learned a lot since then, both

    in terms of PHP and in terms of what read-

    ers expect in a book. A lot of my valuable

    experience in this latter category comes

    from the constant interactions with other

    readers through email and my supporting

    forums (www.DMCInsights.comphorum). A

    fair amount of material is therefore based

    upon frequently asked questions I see.

    How this book compares to my

    others

    Those readers who have come to this book

    from my PHP for the World Wide Web: Visual

    QuickStart Guide may find themselves in a

    bit over their heads. This book does assume

    comfort with standard PHP programming,in particular debugging your own scripts.

    I’m not suggesting you put this book down,but if you find it goes too fast for you, or

    assumes knowledge you don’t currently pos-

    sess, you may want to check out my PHP

    and MySQL for Dynamic Web Sites: Visual

    QuickPro Guide instead.

    If you have read the PHP and MySQL book,or the first edition of this one, I’m hoping

    that you’ll find this to be a wonderful addi-

    tion to your library and skill set.

    xii

    Introduction

    IntroductionAbout PHP 5

    Although version 5 of PHP has been out

    since July 2004 (when the first non-beta

    version was released), there are still a large

    number of servers running older versions

    of PHP, particularly outside of the United

    States. This book does assume you’re using

    PHP 5, although some examples will work

    with older versions of the language.

    The most important change in PHP 5,with respect to this book, is the completely

    different object model and syntax. Object-

    oriented programming in PHP 4 is a rather

    watered-down concept, really not worth

    using in comparison to PHP 5’s OOP. The

    object-oriented chapters use PHP 5 syntax

    exclusively, and that code will not work on

    older versions of the language.

    In addition, PHP 5 added support for the

    Improved MySQL extension, designed for

    use with MySQL 4.1 or later. With only one

    or two exceptions, I use these Improved

    MySQL functions instead of the older, “regu-

    lar” MySQL functions. If your PHP installa-

    tion (or MySQL installation) does not sup-

    port these functions, you’ll need to change

    the code accordingly.

    xiii

    Introduction

    IntroductionWhat You’ll Need

    Just as this book assumes that you already

    possess the fundamental skills to program in

    PHP (and, more important, to debug it when

    things go awry), it also assumes that you

    already have everything you need to follow

    along with the material. For starters, this

    means a PHP-enabled server. At the time of

    this writing, the latest version of PHP was

    5.2, and much of the book depends upon

    your using at least PHP 5.0.

    Along with PHP, you’ll often need a database

    application. I use MySQL for the examples,but you can use anything. And, for the scripts

    in some of the chapters to work—particularly

    the last five—your PHP installation will have

    to include support for the corresponding

    technology, and that technology’s library

    may need to be installed, too. Fortunately

    PHP 5 comes with built-in support for many

    advanced features. If the scripts in a par-

    ticular chapter require special extensions,that will be referenced in the chapter’s intro-

    duction. This includes the few times where

    I make use of a PEAR or PECL class. Nowhere

    in this book will I discuss installation, though,as I expect you should already know or have

    accomplished that.

    As with any issue, should you have questions

    or problems, you can always search the Web

    or post a message in my support forums for

    assistance.

    Beyond PHP, you need the things you should

    already have: a text editor or IDE, an FTP

    application (if using a remote server), and a

    Web browser. All of the code in this book

    has been tested on both Windows XP and

    Mac OS X; you’ll see screen shots in both

    operating systems.

    xiv

    Introduction

    IntroductionSupport Web Site

    I have developed a Web site to support this

    book, available at www.DMCinsights.com

    phpvqp2. This site:

    ◆ Has every script available for download

    ◆ Has the SQL commands available for

    download

    ◆ Has extra files, as necessary, available

    for download

    ◆ Lists errors that have been found in

    the book

    ◆ Has a support forum where you can get

    help or assist others

    ◆ Provides a way to contact me directly

    When using this site, please make sure

    you’ve gone to the correct URL (the book’s

    title and edition are plastered everywhere).

    Each book I’ve written has its own support

    area; if you go to the wrong one, the down-

    loadable files won’t match those in the book.

    Two bonus chapters, “Image Generation”

    and “Creating PDFs,” can be downloaded

    for free. Visit www.peachpit.comtitle

    0321376013 to learn how to register this

    book and access the chapters.

    xv

    Introduction

    IntroductionThis page intentionally left blank At the most basic level good programming is determined by whether or not an appli-

    cation or script works as intended. This is where the beginning programmer will leave

    things, and there is nothing wrong with that. However, the advanced programmer

    will work past that point, striving toward improved efficiency, reliability, security,and portability. This book teaches you how to develop the skills of an advanced PHP

    programmer.

    One thing the advanced PHP programmer does better than the beginner is learning to

    take advantage of more obscure or harder-to-comprehend features of the language. For

    example, while you probably already know how to use arrays, you may not have mas-

    tered multidimensional arrays: creating them, sorting them, and so on. You have writ-

    ten your own functions by this point but may not understand how to use recursion and

    static variables. Issues like these will be discussed as well as other beyond-the-basics

    concepts, like the heredoc syntax and the printfsprintf family of functions.

    1

    Advanced

    PHP Techniques

    1

    Advanced PHP techniquesMultidimensional Arrays

    Because of their power and flexibility, arrays

    are widely used in all PHP programming. For

    advanced uses, the multidimensional array

    often solves problems where other variable

    types just won’t do.

    For the first of the two examples, I’ll demon-

    strate how to sort a multidimensional array.

    It’s a common question users have and isn’t

    as hard as one might think. For the second

    example, I’ll create a database-driven to-do

    list, which can have limitless dimensions

    (Figure 1.1).

    Sorting multidimensional arrays

    Sorting arrays is easy using PHP, thanks to

    the sort, ksort, and related functions.

    You can sort a one-dimensional array by key,by value, in reverse order, etc. But these func-

    tions will not work on multidimensional

    arrays (not as you’d probably like, at least).

    Say you have an array defined like so:

    a = array (

    array (‘key1’ => 940, ‘key2’ => ‘blah’),array (‘key1’ => 23, ‘key2’ => ‘this’),array (‘key1’ => 894, ‘key2’ => ‘that’));

    This is a simple two-dimensional array (an

    array whose elements are also arrays) that

    you might need to sort using key1 (a numeric

    sort) or key2 (an alphabetical sort). To sort a

    multidimensional array, you define your own

    sort function and then tell PHP to use that

    function via the usort, uasort, or

    uksort function. The function you define

    must take exactly two arguments and return

    a value indicating which should come first.

    Figure 1.2 The multidimensional array

    sorted by numeric value (key1).

    Figure 1.1 One use of multidimensional

    arrays will be to create a nested to-do

    list.

    2

    Chapter 1

    Multidimensional ArraysFigure 1.4 An alphabetical sort on

    the example array using key2.

    Figure 1.3 By printing out the values

    of x[‘key1’] and y[‘key1’], one

    can see how the user-defined sorting

    function is invoked.

    To sort the preceding array on the first key,the sorting function would like this:

    function mysort1 (x, y) {

    return (x[‘key1’] > y[‘key1’]);

    }

    Then the PHP code would use this function

    by doing:

    usort (a, ‘mysort1’);

    Figure 1.2 shows the same array at this

    point.

    PHP will continue sending the inner arrays

    to this function so that they may be sorted. If

    you want to see this in detail, print the values

    being compared in the function (Figure 1.3).

    The usort function sorts by values and does

    not maintain the keys (for the outermost

    array). If you used uasort, the keys would

    be maintained, and if you used uksort, the

    sort would be based upon the keys.

    To sort on the second key in the preceding

    example, you would want to compare two

    strings. That code would be (Figure 1.4

    shows the result):

    function mysort2 (x, y) {

    return strcasecmp(x[‘key2’],? y[‘key2’]);

    }

    usort (a, ‘mysort2’);

    Or you could just use strcmp, to perform a

    case-sensitive sort.

    To see this in action for yourself, let’s run

    through an example.

    3

    Advanced PHP Techniques

    Multidimensional ArraysTo sort a multidimensional array:

    1. Create a new PHP script in your text edi-

    tor or IDE, starting with the HTML code

    (Script 1.1).

    
    DTD XHTML 1.0 TransitionalEN”

    “http:www.w3.orgTRxhtml1DTD

    xhtml1-transitional.dtd”>

    
    xhtml” xml:lang=”en” lang=”en”>

    

    
    content=”texthtml; charset=

    iso-8859-1” >