PHP 7 Zend Certification Study Guide

Transcription

1 PHP 7 Zend Certification Study Guide Ace the ZCE 2017-PHP Exam Andrew Beak

2 PHP 7 Zend Certification Study Guide Andrew Beak Grafham, Cambridgeshire, United Kingdom ISBN-13 (pbk): ISBN-13 (electronic): Library of Congress Control Number: Copyright 2017 by Andrew Beak This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Trademarked names, logos, and images may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, logo, or image we use the names, logos, and images only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Cover image by Freepik ( Managing Director: Welmoed Spahr Editorial Director: Todd Green Acquisitions Editor: Nikhil Karkal Development Editor: James Markham Technical Reviewer: Nico Loubser Coordinating Editor: Prachi Mehta Copy Editor: Kezia Endsley Distributed to the book trade worldwide by Springer Science+Business Media New York, 233 Spring Street, 6th Floor, New York, NY Phone SPRINGER, fax (201) , orders-ny@springer-sbm.com, or visit Apress Media, LLC is a California LLC and the sole member (owner) is Springer Science + Business Media Finance Inc (SSBM Finance Inc). SSBM Finance Inc is a Delaware corporation. For information on translations, please rights@apress.com, or visit Apress titles may be purchased in bulk for academic, corporate, or promotional use. ebook versions and licenses are also available for most titles. For more information, reference our Print and ebook Bulk Sales web page at Any source code or other supplementary material referenced by the author in this book is available to readers on GitHub via the book's product page, located at For more detailed information, please visit Printed on acid-free paper

3 For Duckems, Beastly, and Bratface for whom I d change the world if I had the source code

4 Contents About the Author... xix About the Technical Reviewer... xxi Introduction... xxiii Chapter 1: PHP Basics... 1 Introduction... 1 Basic Language Features... 1 Inserting PHP into Web Pages... 1 Language Constructs... 3 Comments... 5 Representing Numbers... 5 Variables... 6 Variable Types...6 Naming Variables...10 Checking If a Variable Has Been Set...11 Constants Superglobals Magic Constants Operators Arithmetic...15 Logic Operators...16 v

5 Ternary Operator...16 Null Coalescing Operator...17 Spaceship...18 Bitwise...18 Bit Shifting...19 Bitwise NOT...20 Assignment Operators...21 Reference Operator...22 Comparison Operators...22 Two More Operators...23 Control Structures Conditional Structures...24 Loops...25 Breaking Out of Loops...26 Namespaces...26 Fully Qualified Namespace Names...27 Configuration Where Settings May Be Set or Changed...28 Php.ini...29 User INI Files...29 Apache Version of INI Files...29 Performance Memory Management...30 Symbols Are Pointed to zval Containers Arrays and Objects...31 Memory Leaks in Arrays and Objects...32 Garbage Collection...32 The Opcode Cache...32 Extensions...33 vi

6 Chapter 2: Functions Arguments Argument Type Declarations...39 Optional Arguments...42 Overloading Functions...43 Variadics...44 References Variable Functions Returns Return Type Declarations...46 Return Void...47 Return by Reference...47 Variable Scope in Functions Lambda and Closure Early and Late Binding...49 Binding Closures to Scopes...50 Self-Executing Closures...51 Callables Chapter 3: Strings and Patterns Declaring Strings Embedding Variables...57 Control Characters...59 Heredoc and Nowdoc...60 Referencing Characters in Strings PHP and Multibyte Strings Unicode...62 Telling Clients How a String Is Encoded...62 Changing Between Encoding Schemes...62 vii

7 Practical Example...63 Matching Strings...64 Extracting Strings Searching Strings Useful Tips...67 Quick Overview of Search Functions...68 Replacing Strings...68 Formatting Strings Formatting Numbers String Patterns: Regular Expressions Delimiters...72 Meta-Characters...72 Generic Character Types...73 Boundaries...74 Character Classes...74 Matching More Than Once...74 Capturing Groups...75 Greed and Laziness...76 Getting All Matches...76 Naming Groups...77 Pattern Modifiers...78 Chapter 4: Arrays Declaring and Referencing Arrays Functions That Create an Array Array Operators Proper ties of PHP Array Keys Filling Up Arrays...88 Push, Pop, Shift, and Unshift (Oh My!)...90 viii

8 Comparing Arrays array_diff()...91 array_intersect()...92 User-Defined Matching Functions...92 Quick List of Comparison Functions...94 Combining Arrays Splitting Arrays Destructuring Arrays Calculating with Arrays Iterating Through Arrays Looping Through Arrays...99 Using Array Cursors Walking Through Arrays Sorting Arrays Natural Order Sorting Standard PHP Library (SPL): ArrayObject Class Chapter 5: Object-Oriented PHP Declaring Classes and Instantiating Objects Autoloading Classes Visibility or Access Modifiers Instance Properties and Methods Properties Methods Static Methods and Properties Static Properties Working with Objects Copying Objects Serializing Objects ix

9 Casting Between Arrays and Objects Casting Objects to String Class Aliases Constructors and Destructors Constructor Precedence Constructor Parameters Inheritance The final Keyword Overriding Interfaces Abstract Classes Anonymous Classes Reflection Type Hinting Class Constants Late Static Binding Forwarding calls Magic ( *) Methods get and set isset and unset call and callstatic invoke debuginfo More Magic Functions Standard PHP Library (SPL) Data Structures Iterators Exceptions x

10 File Handling ArrayObject Observer Pattern Generators Yield Keyword Yielding with Keys Yielding NULL Yielding by Reference Returning from a Generator Generator Delegation Traits Declaring and Using Traits Namespacing Traits Inheritance and Precedence Conflict Resolution Visibility Chapter 6: Security Configuration Errors and Warnings Disabling Functions and Classes PHP as an Apache Module PHP as a CGI Binary Running PHP-FPM Session Security Session Hijacking Session Fixation Improving Session Security xi

11 Cross-Site Scripting Mitigating XSS Attacks Cross-Site Request Forgeries SQL Injection Prepared Statements Escaping General Principles Remote Code Injection Functions That Evaluate Strings as Code Gaming include and require Injection Filter Input Escape Output Avoid Log Poisoning Encryption and Hashing Algorithms Encryption in PHP Hash Functions Secure Random Strings and Integers Salting Passwords Checking a Password A Quick Note on Error Messages File Uploads Database Storage Avoid Publishing Your Password Online xii

12 Chapter 7: Data Formats and Types XML The Basics of XML Well-Formed and Valid XML Processing Instructions XML Transformations with PHP XSL Parsing XML in PHP DOM SimpleXML SOAP What SOAP Does Using a SOAP Service Offering a SOAP Service REST Web Services Application and Resource States REST Verbs HATEOAS Request Headers Response Headers and Codes Sending Requests JSON Date and Time Formatting Dates Date Calculations Manual Date Calculations Comparing Dates xiii

13 xiv PHP SPL Data Structures Interfaces Related to Data Structures Lists Heaps Arrays Maps Summary of SPL Data Structures Chapter 8: Input-Output Files Opening Files File Modes File Mode Flags Reading Files Writing to Files File System Functions Directories File Information Managing Files Determining the Type of a File System Object Magic File Constants Streams Stream Wrappers Filters Stream Contexts Chapter 9: Web Features Request Types Request Data The Request Superglobal POST GET PUT...222

14 Sessions Starting a Session Session Identifier and Session Variables Ending a Session Session Handlers File Uploads Limiting the Size of Uploads Temporary Files Forms Form Elements Arrays in HTML Forms Selecting Multiple Items from a List Cookies Setting Cookies Retrieving Cookies HTTP Headers Sending Headers Tracking Headers HTTP Authentication HTTP Status Codes Output Control Functions Chapter 10: Databases and SQL Database Basics Keys Indexes Relationships SQL Data Types Numeric Types Character Types xv

15 Working with SQL Creating a Database and Table Dropping Database and Tables Retrieving Data Inserting New Data Updating Data Aggregating Data Grouping Data Joins Join Types Prepared Statements Transactions PHP Data Object (PDO) Connecting to PDO Transactions in PDO Fetching PDO Results Prepared Statements in PDO Repeated Calls to PDO Prepared Statements Chapter 11: Error Handling Throwables The Throwable Interface Errors Error Constants Using an Error-Handler Function Displaying or Suppressing Non-Fatal Error Messages Error-Handling Functions xvi

16 Exceptions Extending Exception Classes The Exception Hierarchy Handling Exceptions Catching Exceptions The finally Block Setting the Default Exception Handler Chapter 12: Exercises Appendix: Quiz Answers Chapter 1: PHP Basics Chapter 2: Functions Chapter 3: Strings and Patterns Chapter 4: Arrays Chapter 5: Object-Oriented PHP Chapter 6: Security Chapter 7: Data Structures Chapter 8: Input-Output Chapter 9: Web Features Chapter 10: Databases and SQL Chapter 11: Error Handling Chapter 12: Exercises Index xvii

17 About the Author Andrew Beak is a software architect responsible for the cloud platform of an Internet television company. He is a ZCE and has over six years of professional experience working in PHP. He has been the technical lead for teams in South Africa and the United Kingdom. His enjoyment for writing coupled with his interest in empowering staff inspired him to write this book. He has also written a book on scaling PHP and published a series of video courses focused on the Zend examinations. xix

18 About the Technical Reviewer Nico Loubser is the lead software developer and team lead in a company that specializes in the payment industry, with a degree in information systems. He has been working in PHP since PHP 3.8, as well as working in numerous industries, and is a serious PHP 7 enthusiast. xxi

19 Introduction Welcome to what I hope is an accessible reference that helps you quickly find and learn relevant facts about the PHP language. I m writing it with the following readers in mind: Intermediate PHP programmers with two or three years of experience who are hoping to sit for the Zend 2017 certification exams in the PHP 7.1 language. Programmers who are proficient in another language but want a quick reference book to dive into PHP. This book is specifically not an introduction to programming and no attempt is made to introduce basic topics such as what a variable is. It is purely a reference to learn the idiosyncrasies of PHP and serve as a guide toward certifying. Additionally, it does not intend to replace the PHP manual but rather to focus the reader s attention on aspects of PHP relevant to the Zend certification exams. To that end, I make liberal use of footnotes linking to manual pages and other reference pages. This guide cannot possibly cover the full depth of the PHP manual, 1 and you cannot consider yourself prepared until you have worked through the manual pages. It is essential to follow the footnote links, read the page, and even follow some links through the PHP manual related to the topic. This book focuses on PHP 7.1 and in order to keep focused on the exam syllabus does not attempt to exhaustively explain what features are available in which version of PHP. You can assume that if a feature is referenced in this book then it is available in PHP 7.1. You won t need to know when a feature was introduced into PHP, but you will need to know what features are deprecated in PHP 7.1. I've tried to keep that in mind when giving information about the availability of a feature. Wherever possible, I'll flag where something has changed from PHP 5.6, especially where it is not backward compatible. This book tries to avoid having an opinion about coding standards such as PSR2, but it is strongly recommended that a practicing developer learn these in parallel. You won t be asked about them on the exam and so I won't teach them here. Some paragraphs in this book are marked up with symbols, as explained next. 1 xxiii

20 Introduction Caution These paragraphs draw your attention to something that might be counter-intuitive or a part of PHP weirdness. Note Tip These paragraphs deserve special attention. These paragraphs draw your attention to potential exam questions. The Zend Certification Syllabus Zend certification is one of the few industry certifications that is widely recognized as an established benchmark for proficiency in PHP. Part of why this certification is so well respected is that it is not easy to attain. To pass your exam, you need to have an in-depth knowledge of a wide area of topics in PHP programming. This book aims to highlight the topics that are important in the certification examination. I ve included a bunch of quizzes that test the topics, and if you notice any gaps in your knowledge, you should make sure to go carefully through the relevant sections in the manual. The actual exam consists of about 70 questions drawn from a pool. Questions will vary in difficulty and will sometimes require you to apply the principles from more than one area of the syllabus to solve them. There are ten topics covered in the examination. Zend places varying amount of importance to the topics in the exam. You can find a list of exam topics on the Zend web site. You ll notice that this guide has a chapter for each of the topics in the list: Very Important Average Importance Lower Importance PHP basics Functions Databases and SQL Object-Oriented PHP Web Features Data Format and Types Security Strings Input-Output Arrays Error Handling The sections on PHP basics, object-oriented programming, and security are regarded as being the most important and are given the most weight in the exam. There are a lot of tricky questions in the PHP Basics section, so don t be fooled by the inclusion of the word basics in the topic title. It s one of the three most important topics in the exam syllabus, so don t skimp on the time you spend finding the gaps in your knowledge. xxiv

21 Introduction The sections on databases, data formats and types, and input-output are considered less important. You ll still need to know them, however, as exam questions will often rely on a broad knowledge of PHP and may require you to apply knowledge from different topics. The exam has a mixture of multiple choice and free text questions. You ll be required to code short snippets to answer some questions. Although you won t be required to have an encyclopedic knowledge of the PHP manual, you will be asked questions about function parameters, what function to use in a particular situation, common classes, exceptions, and other elements of PHP. Unless they note otherwise, all questions assume that you are working with PHP 7.1 that has been configured with the recommended settings. You can assume that error display is set on and that error reporting is set to E_ALL. You can mark questions for review and come back to them later. Don't spend more time than is allocated to a question; That just makes the following questions more difficult because you have less time! Finally, there is no negative marking in the exam. You won t be penalized for an incorrect answer, so taking a guess works in your favor. xxv