QUE PHP by Example (2002).pdf

PHP

201 West 103rd Street

Indianapolis, Indiana 46290

To b y Butzon

BY EXAMPLE

PHP By Example

Associate Publisher

Dean Miller

Senior Acquisitions Editor

Jenny L. Watson

Development Editor

Sean Dixon

Technical Editor

Robert Grieger

Managing Editor

Thomas F. Hayes

Project Editor

Karen S. Shields

Indexer

Chris Barrick

Proofreaders

Bob LaRoche

Jeannie Smith

Team Coordinator

Cindy Teeters

Interior Designer

Karen Ruggles

Cover Designer

Rader Design

stored in a retrieval system, or transmitted by any means, elec-

tronic, mechanical, photocopying, recording, or otherwise, with-

out written permission from the publisher. No patent liability is

assumed with respect to the use of the information contained

herein. Although every precaution has been taken in the prepa-

ration of this book, the publisher and author assume no respon-

sibility for errors or omissions. Nor is any liability assumed for

damages resulting from the use of the information contained

herein.

International Standard Book Number: 0-7897-2568-1

Library of Congress Catalog Card Number: 2001090370

Printed in the United States of America

First Printing: November 2001

04 03 02 01

Trademarks

All terms mentioned in this book that are known to be trade-

marks or service marks have been appropriately capitalized. Que

cannot attest to the accuracy of this information. Use of a term

in this book should not be regarded as affecting the validity of

any trademark or service mark.

Warning and Disclaimer

Every effort has been made to make this book as complete and

as accurate as possible, but no warranty or fitness is implied.

The information provided is on an “as is” basis. The author and

the publisher shall have neither liability nor responsibility to

any person or entity with respect to any loss or damages arising

from the information contained in this book.

4321

iii

Contents at a Glance

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

Part I Getting Started with Programming in PHP 5

1Welcome to PHP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

2 ariables and Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

3 Program Input and Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

4 Arithmetic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

5 String Manipulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88

Part II Control Structures 113

6 The if , elseif , and else Statements . . . . . . . . . . . . . . . . . . . . . .114

7 The switch Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .136

8Using while and do-while . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .152

9Using for and foreach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .170

Part III Organization and Optimization of Your Program 185

10 Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .186

11 Classes and Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .214

12 Using Include Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .240

Part IV Advanced PHP Features

261

13 Creating Dynamic Content with PHP and a

MySQL Database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .262

14 Using PHP for Password Protection . . . . . . . . . . . . . . . . . . . . . . .292

15 Allowing Visitors to Upload Files . . . . . . . . . . . . . . . . . . . . . . . . .314

16 Cookies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .336

17 Putting It All Together . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .352

APPENDIX 373

A Debugging and Error Handling . . . . . . . . . . . . . . . . . . . . . . . . . .374

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .386

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .394

Table of Contents

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

Part I Getting Started with Programming in HP 5

1Welcome to PHP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Why PHP? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

If You’re New to Programming… . . . . . . . . . . . . . . . . . . . . . . . . . .10

Writing a Basic PHP Program . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Programming Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Good Style: Using Whitespace and Comments . . . . . . . . . . .17

How Embedded Programming Works . . . . . . . . . . . . . . . . . .20

Server-Side Versus Client-Side Scripting . . . . . . . . . . . . . . . . . . . .22

Running Your New Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

What If It Didn’t Work? . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

2 ariables and Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Introduction to Variables and Constants . . . . . . . . . . . . . . . . . . . .30

Declaration and Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Declaring Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Assigning Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

Declaring a Constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Deciding Whether to Use a Variable or Constant . . . . . . . . .35

Variable Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

Integers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

Floating-Point Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

Type Casting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Necessity of Type Casting . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Variable References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45

3 Program Input and Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

Revisiting Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

The echo Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

Using Here-doc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54

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