1. Introduction

The PDF in the document is HERE.

The code in this document is HERE.

This document is a product of Claude from Anthropic. This is a rewrite, for the PHP 8 language, of the course “Introduction to the PHP 7 Language by Example” written by Serge Tahé in July 2019. It retains the outline, examples, and central theme, while changing the language:

the 2019 course used PHP 7.3. Since then, PHP has undergone six major versions: 8.0 (2020), 8.1 (2021), 8.2 (2022), 8.3 (2023), 8.4 (2024), and 8.5 (2025). This document uses PHP 8.5;
between these two versions, PHP has changed significantly: many features have been introduced (types, enumerations, read-only classes, [match], named arguments…), and many others have been deprecated: They still work, but PHP displays a warning message each time they are used, to alert users that they will be removed in a future version. The code in this document does not use any deprecated features: all scripts were run with PHP 8.5 configured to display all errors, warnings, and deprecations, and no [Deprecated] messages appear in their results;
The tools have also changed: the [VS Code] editor replaces the [NetBeans] IDE; the [PHPUnit] testing framework replaces [Codeception]; the [curl] command replaces the [Postman] tool, the [Symfony Mailer] library replaces [SwiftMailer], which has been deprecated, and the [Mailpit] mail server replaces [hMailServer], which has also been deprecated.

This document provides a list of PHP console scripts in various areas (language structures, classes, access to files, databases, and the Internet). Web programming is addressed through web services. In this document, a web service refers to any web application that produces data (plain text, JSON, XML) rather than HTML pages. These are data servers, not web page servers—a combination of HTML, CSS, and JavaScript. It covers classic web concepts (the HTTP protocol, JSON or XML responses, session management, and authentication) that are also used in traditional web programming. The final section of the document also builds a HTML web application.

1.1. The Role of PHP in a Client/Server Application

Nowadays, it is common to build web applications in client/server mode:

In [1], the web browser displays web pages for a user. These pages contain JavaScript, which implements a client for a [2] data web service, as well as a client for a [3] web page fragment server. JavaScript frameworks such as [Vue.js], [React], or [Angular] are designed for this purpose;
In [2], the web server is a data server. It can be written in any language, for example, in PHP. It does not generate web pages in the traditional sense (HTML, CSS, JavaScript) except perhaps the first time. However, this first page can be obtained from a traditional web server ([3]). The JavaScript for the initial page will then generate the application’s various web pages by retrieving the [4] data to be displayed from the data server [2]. It can also retrieve web page fragments ([5]) to format this data from the web page server ([3]);
In [4], the user initiates an action;
in [6, 7], the user receives data formatted with a web page fragment.

In this document, we will write client/server applications in PHP with the following structure:

Here we have a client/server application written entirely in PHP. A [9] console script will query a [4] data server. What you’ll learn here about writing the data service can be reused in a web application: the data service in PHP can be kept, and the PHP client can be replaced by a JavaScript client.

As the central theme of this document, we will build an income tax calculation service in 13 versions. Version 12 will have the following architecture:

The server’s [web] layer will have a MVC architecture (Model–View–Controller). It will be able to respond in JSON, XML, or HTML. The entire course is aimed at building this version, which version 13 secures.

1.2. What Has Changed Between PHP 7 and PHP 8

The new features in PHP 8 are introduced throughout the chapters as they are needed, and are always compared to how things were done in the PHP 7 course. Here are the main ones, along with the chapter in which they appear:

New Feature	Version	Chapter
Strict typing ([declare(strict_types=1)]), parameter and return types ([mixed]), union types ([int\|float]), nullable types ([?string])	7.0 to 8.0	The Basics of PHP
the expression [match], the null-safe operator [?->], named arguments	8.0	The Basics of PHP
[str_contains], [str_starts_with], [str_ends_with], [array_is_list], [json_validate], [array_find], [array_any], [array_all], [array_first], [array_last]	8.0 to 8.5	The Basics of PHP
[fn] arrow functions, [f(...)] first-class callables, [\|>] pipe operator	7.4 to 8.5	The Basics of PHP
Typed attributes, constructor parameter promotion	7.4, 8.0	Classes
Properties and read-only classes [readonly]	8.1, 8.2	Classes
Enumerations [enum]	8.1	Classes
Property hooks and asymmetric visibility [public private(set)]	8.4	Classes
[clone] with attribute modification, the [#[\Override]]	8.5, 8.3	Classes
The intersection types [A&B] and [new] in the default values	8.1	Interfaces
Errors that have become exceptions ([TypeError], [ValueError], [DivisionByZeroError]…), [throw] expression, [catch] without a variable	8.0	Exceptions and Errors
Constants in traits	8.2	Traits
[PDO::connect()] and the subclasses [Pdo\Mysql], [Pdo\Pgsql]	8.4	MySQL
the attribute [#[\SensitiveParameter]]	8.2	Application exercise, versions 5 and later
the new API [Dom\XMLDocument]	8.4	XML Document Processing

Conversely, here are the main features used by the PHP 7 course that are now deprecated or removed, along with their replacements in this document:

Feature from the PHP 7 course	Status	Replacement
Dynamic attributes (created by simple assignment [$object->x = 1])	Deprecated in 8.2	declared attributes, or the class [stdClass]
interpolation ["${var}"]	deprecated in 8.2	["$var"] or ["{$var}"]
[utf8_encode], [utf8_decode]	Deprecated in 8.2	[mb_convert_encoding]
Implicitly nullable parameters [Type $x = null]	Deprecated in 8.4	[?Type $x = null]
conversions [(integer)], [(boolean)], [(double)]	deprecated in 8.5	[(int)], [(bool)], [(float)]
The constants *[PDO::MYSQL_ATTR_]**	deprecated in 8.5	*[Pdo\Mysql::ATTR_]**
Functions *[imap_]**	removed from the core of PHP in 8.4	POP3 / IMAP clients written using sockets
the [SwiftMailer] library	discontinued	[Symfony Mailer]
the [php-mime-mail-parser] library	requires an extension that is not provided	[zbateson/mail-mime-parser]
[Codeception]	Replaced	[PHPUnit] 12
Apache 2.2 syntax [deny from all]	obsolete	[Require all denied] (Apache 2.4)

1.3. Tools Used

The examples were written and tested using the following tools (their installation is described in the next chapter):

[PHP] 8.5, configured to report all errors, warnings, and deprecations;
The [Laragon] 8 package, which combines [Windows] and PHP 8.5, the [Apache] 2.4 web server, the [MySQL] 8.4 DBMS, the [Redis] server, and the [Composer] dependency manager; the [PostgreSQL] DBMS can be added with just a few clicks;
the [Visual Studio Code] editor (VS Code) and its extension [PHP Intelephense];
the PHP libraries installed with [Composer]: [symfony/http-foundation], [symfony/http-client], [symfony/mailer], [symfony/mime] 8, [predis/predis] 3, [zbateson/mail-mime-parser] 3, and, for testing, [phpunit/phpunit] 12;
the test mail server [Mailpit] and, for the IMAP protocol, an IMAP server (a [Gmail] account, or a local server);
the command-line tool [curl], included with [Windows], which displays raw HTTP exchanges;
a browser ([Chrome], [Firefox], [Edge]…).

The scripts in this document are commented, and their console output is reproduced. Additional explanations are sometimes provided. This document requires active reading: to understand a script, you must read its code, its comments, and its execution results. The screenshots of the web pages were taken using a program-controlled browser: these are actual pages from the course applications.

1.4. Examples

The code in this document is stored in a single folder named [php8-oct-2026]:

php8-oct-2026/
├── composer.json        the libraries used by the course
├── phpunit.xml          the PHPUnit test configuration
├── vendor/              the libraries, installed by Composer (to be created, see next chapter)
├── scripts-console/     the scripts run in a terminal
│   ├── basics/          the basics of the language
│   ├── json/            JSON encoding / decoding
│   ├── classes/         classes
│   ├── interfaces/      interfaces
│   ├── exceptions/      exceptions and errors
│   ├── traits/          traits
│   ├── three-layers/    a layered application
│   ├── mysql/           using the MySQL DBMS
│   ├── inet/            network functions (TCP, HTTP, SMTP, POP3, IMAP)
│   ├── web-clients/     the web service clients
│   ├── xml/             processing XML documents
│   └── tax/             the tax calculation, versions 1 to 12 (the console versions and the clients)
└── scripts-web/         the scripts run by the Apache server
    ├── 01/ … 08/        the web services
    └── tax/             the tax calculation servers, versions 8 to 13

The folder [php8-oct-2026] must be placed inside the folder [www] of [Laragon] (for example, [C:\laragon\www\php8-oct-2026]): This is the root directory of the [Apache] web server. The web scripts are then accessible at URLs of the form [http://localhost/php8-oct-2026/scripts-web/...].

1.5. Document Contents

Chapter	Contents
Installation	Laragon, PHP 8.5, VS Code, Composer
The Basics of PHP	Variables, Types, Strict Typing, Arrays, Strings, Functions, Text Files, JSON
Practical Exercise, Versions 1 and 2	Tax calculation, using functions
Classes, Interfaces	classes, inheritance, typed attributes, [readonly], enumerations, property hooks, interfaces
Exceptions and errors	The [Throwable] hierarchy of PHP 8, its own exceptions
Application exercise, version 3	Tax calculation using classes
Traits, layered applications	Reusing code, architecture [dao] / [business] / [console]
Practical Exercise, Version 4	Layered tax calculation, tests [PHPUnit]
Using the MySQL DBMS	PDO, prepared SQL statements, transactions
Practical Exercise, Versions 5 through 7	Tax data in a database: MySQL, then PostgreSQL, then either one
Network Functions	TCP, HTTP, SMTP, POP3, IMAP
Web services	Static and dynamic pages, JSON, settings, sessions, authentication, HTTPS
Practical Exercise, Versions 8 through 10	A tax calculation server and its client, logging, sending emails, cache [Redis]
XML document processing	SimpleXML, the DOM API of PHP 8.4
Application Exercise, Version 11	The tax calculation server responds with XML
Practical Exercise, Version 12	An MVC server responding with JSON, XML, or HTML; a web application; a client of the JSON service
Practical Exercise, Version 13	Secure access to the application’s files

These are all chapters for beginners in PHP. However, it is assumed that the reader has already programmed in some language and knows what a variable, a loop, and a function are.