The PHP Workshop: Learn to build interactive applications and kickstart your career as a web developer

603 Pages·2019·8.599 MB·English

by  Alexandru Busuioc, David Carr, Markus Gray, Vijay Joshi, Mark McCollum, Bart McLeod, M A Hossain Tonu

The PHP Workshop
A New, Interactive Approach to Learning PHP
Alexandru Busuioc, David Carr, Markus Gray, Vijay Joshi,
Mark McCollum, Bart McLeod, and M A Hossain Tonu
The PHP Workshop
Copyright © 2019 Packt Publishing
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Authors: Alexandru Busuioc, David Carr, Markus Gray, Vijay Joshi, Mark McCollum,
Bart McLeod, and M A Hossain Tonu
Technical Reviewers: Jordi Martinez and Kristian Secor
Managing Editor: Rutuja Yerunkar
Acquisitions Editor: Sarah Lawton
Production Editor: Samita Warang
Editorial Board: Shubhopriya Banerjee, Bharat Botle, Ewan Buckingham, Megan Carlisle,
Mahesh Dhyani, Manasa Kumar, Alex Mazonowicz, Bridget Neale, Dominic Pereira,
Shiny Poojary, Abhishek Rane, Erol Staveley, Ankita Thakur, Nitesh Thakur, and
Jonathan Wray
First Published: October 2019
Production Reference: 2201119
ISBN: 978-1-83864-891-6
Published by Packt Publishing Ltd.
Livery Place, 35 Livery Street
Birmingham B3 2PB, UK
Table of Contents
Preface i
Chapter 1: Introducing PHP 1
Introduction .................................................................................................... 2
Getting Started with PHP Web Development ............................................. 2
Built-in Templating Engine .................................................................................. 3
PHP in the Interactive Shell ................................................................................ 4
Exercise 1.1: Printing Hello World to the Standard Output ............................ 4
Exercise 1.2: Printing Hello World by Executing a PHP File ............................ 6
Assigning and Using Variables ........................................................................... 7
Creating and Assigning Variables to Print Simple Messages
on the Web Browser ........................................................................................... 8
Exercise 1.3: Using Input Variables to Print Simple Strings ............................ 9
Exercise 1.4: Using the Built-in Server to Print a String ................................ 11
HyperText Markup Language ..................................................................... 12
Cascading Style Sheets ................................................................................ 15
Exercise 1.5: Creating a Login Form Page Using Bootstrap .......................... 18
Exercise 1.6: Printing PHP Code Output between HTML Tags ...................... 20
Using the Server Variable ........................................................................... 21
Exercise 1.7: Displaying Server Information ................................................... 21
Other Predefined Variables .............................................................................. 22
Assignment by Value and by Reference .......................................................... 23
Exercise 1.8: Assigning a Variable by Reference and Changing its Value ... 23
Using isset to Check for Variable Declaration ................................................ 25
Exercise 1.9: Using isset to Check whether a Variable Has Been Set .......... 26
Activity 1.1: Displaying Query Strings in the Browser ................................... 27
Summary ....................................................................................................... 28
Chapter 2: Types and Operators 31
Introduction .................................................................................................. 32
What are Data Types? .................................................................................. 32
Integers ............................................................................................................... 32
Strings .................................................................................................................. 33
Single and Double-Quoted Strings ................................................................... 33
Heredoc and Nowdoc Syntaxes ....................................................................... 35
Floats ................................................................................................................... 37
Boolean ............................................................................................................... 37
Exercise 2.1: Using Simple Data Types ........................................................... 38
Arrays .................................................................................................................. 40
Indexed and Associative Arrays ....................................................................... 41
Adding and Removing Items from an Array ................................................... 45
Exercise 2.2: Creating a Multidimensional Array .......................................... 48
Scalar Types .................................................................................................. 51
Type Conversion ................................................................................................. 52
Exercise 2.3: Converting a Boolean to an Integer .......................................... 54
Exercise 2.4: Converting an Integer to a String ............................................. 55
Exercise 2.5: Converting Centimeters to Meters ............................................ 57
Operators and Expressions ........................................................................ 58
Arithmetic Operators ........................................................................................ 59
String Operators ................................................................................................ 59
Bitwise Operators .............................................................................................. 60
Assignment Operators ...................................................................................... 61
Comparison Operators ...................................................................................... 62
Increment/Decrement Operators .................................................................... 63
Logical Operators ............................................................................................... 63
Array Operators ................................................................................................. 64
Conditional Assignment Operators ................................................................. 64
Activity 2.1: Printing the BMI of a User ........................................................... 64
Summary ....................................................................................................... 65
Chapter 3: Control Statements 67
Introduction .................................................................................................. 68
Boolean Expressions ................................................................................... 70
Boolean Constants ....................................................................................... 71
Logical Operators ......................................................................................... 71
The not Operator ............................................................................................... 72
The and Operator .............................................................................................. 72
The or Operator ................................................................................................. 72
The xor Operator ............................................................................................... 73
Short-Circuit Evaluation and Operator Precedence ...................................... 73
The Precedence of Logical Operators ............................................................. 74
|| versus or ...................................................................................................74
&& versus and ...............................................................................................75
Comparison Operators ...................................................................................... 76
Branching ...................................................................................................... 77
The if Statement ................................................................................................. 78
The if…else Statement ....................................................................................... 79
Exercise 3.1: Creating a Basic Script to Implement the if...else Test Case .. 80
Exercise 3.2: Implementing the Nested if...else Structure ............................ 81
The Ternary Operator ....................................................................................... 83
The if…elseif…else Statement .......................................................................... 83
Exercise 3.3: Creating a Script Using the if... elseif... else Statement .......... 85
The switch Case .................................................................................................. 86
Exercise 3.4: Creating a Script to Implement a Switch Case ......................... 90
Looping .......................................................................................................... 92
Bounded Loops versus Unbounded Loops ..................................................... 92
The while Loop ................................................................................................... 93
Exercise 3.5: Printing the Numbers 1 to 10 Using a while Loop ................... 94
The do…while Loop ............................................................................................ 96
Exercise 3.6: Converting a while Loop to a do...while Loop .......................... 97
The for Loop ....................................................................................................... 98
Exercise 3.7: Using a for Loop to Print the Days of the Week ................... 100
The foreach Loop ............................................................................................ 101
Exercise 3.8: Using a foreach Loop to Print the Days of the Week .......... 102
Nesting Loops .................................................................................................. 103
Exercise 3.9: Using Nested foreach Loops ................................................... 105
The break Statement ...................................................................................... 108
Exercise 3.10: Using a break Statement to Terminate
a Loop's Execution .......................................................................................... 109
The continue Statement ................................................................................ 110
Exercise 3.11: Using continue to Skip an Item in a List .............................. 110
Alternative Control Syntaxes ........................................................................ 112
Using System Variables .................................................................................. 113
Activity 3.1: Creating a Movie Listing Script
to Print Movies per Director .......................................................................... 113
Tips for Control Structures ............................................................................ 114
Summary .................................................................................................... 115
Chapter 4: Functions 117
Introduction ................................................................................................ 118
What is a Callable? ..................................................................................... 119
Exercise 4.1: Using Built-in Functions ........................................................... 121
Types of Callables ........................................................................................... 124
Language Constructs ................................................................................. 125
Introduction to Built-In Functions ........................................................... 126
Finding Built-In Functions .............................................................................. 127
Parameters and Return Values ..................................................................... 128
Passing Parameters by Reference ................................................................ 129
Passing Scalar Variables by Reference ......................................................... 130
Optional Parameters ...................................................................................... 133
Exercise 4.2: Working with print_r() .............................................................. 134
A Varying Number of Parameters ................................................................. 135
Flag Parameters .............................................................................................. 136
Exercise 4.3: Using Built-In Functions with Arrays ...................................... 137
Introduction to User-Defined Functions ................................................. 142
Naming Functions ........................................................................................... 142
Documenting Your Functions ........................................................................ 142
Namespaced Functions .................................................................................. 143
Pure Functions ................................................................................................ 144
Scope ................................................................................................................ 144
The $GLOBALS Superglobal Array ................................................................. 145
Exercise 4.4: Using the $GLOBALS array ...................................................... 146
The Single Responsibility Principle ............................................................... 147
The function Keyword .................................................................................... 148
Identifier .......................................................................................................... 148
Type Hints ........................................................................................................ 149
The Spread Operator (…) with Type Hints ................................................... 149
Parameters in User-Defined Functions ........................................................ 151
Return Types in User-Defined Functions ..................................................... 152
Signature .......................................................................................................... 152
Returning a Value ........................................................................................... 153
Parameters and Arguments .......................................................................... 153
Optional Parameters ...................................................................................... 154
Parameters Passed by Reference to Our Function ..................................... 155
Default Values for Parameters ...................................................................... 155
Exercise 4.5: Writing a Function that Adds Two Numbers ......................... 156
Variable Functions .......................................................................................... 158
Anonymous Functions .................................................................................... 158
Using a Variable from Outside of Scope Inside
an Anonymous Function ................................................................................ 159
Exercise 4.6: Working with Anonymous Functions ..................................... 159
Exercise 4.7: Creating Variable Functions .................................................... 161
Exercise 4.8: Playing with Functions ............................................................. 162
Activity 4.1: Creating a Calculator ................................................................. 164
Summary ..................................................................................................... 165
Chapter 5: Object-Oriented Programming 167
Introduction ................................................................................................ 168
The Object-Oriented Approach ................................................................ 169
OOP Concepts .................................................................................................. 170
Classes ............................................................................................................. 172
Instantiating a Class ...................................................................................... 173
Class Attributes ............................................................................................... 174
Class Constants ............................................................................................... 176
The $this Variable ........................................................................................... 177
Class Methods ................................................................................................. 177
Exercise 5.1: Using the Getter and Setter Methods .................................... 179
Constructor ...................................................................................................... 182
Destructor ........................................................................................................ 183
Exercise 5.2: Instantiating the Class and Printing the Details ................... 185
Inheritance ...................................................................................................... 189
Exercise 5.3: Implementing Inheritance ...................................................... 192
Access Modifiers ............................................................................................ 195
Exercise 5.4: Applying Access Modifiers ....................................................... 198
Static Fields and Methods .............................................................................. 202
parent:: and self:: ............................................................................................ 204
Exercise 5.5: Applying a Static Member ....................................................... 205
Class Abstraction ............................................................................................ 206
Exercise 5.6: Implementing an Abstract Class ............................................. 208
Interfaces .................................................................................................... 213
Exercise 5.7: Implementing an Interface ..................................................... 216
Abstract Classes versus Interfaces ............................................................... 219
Class Type Hinting Plays a Role in Dependency Injection .......................... 220
Overriding .................................................................................................. 222
Attribute Overriding ....................................................................................... 222
Method Overriding ......................................................................................... 222
Exercise 5.8: Overriding an Inherited Method ............................................ 223
Overloading ..................................................................................................... 225
Attribute Overloading .................................................................................... 227
Method Overloading ....................................................................................... 230