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In this tutorial, you will learn what the PHP programming language is and how to write your first PHP program with this programming language. Also, I will expose the phases of the Zend Engine, especially the PHP lexical token, with an example.

On the other hand, you will also learn the differences between the interpreter and the compiler, the dynamic web page and the static page.

Also, you will learn how to execute the PHP command on your operating system using the CLI or terminal.

PHP is the first and most popular scripting language in terms of webpage development. Also, it can be embedded with HTML markup.

In the next few lines, I’ll explain what PHP means.

PHP is a server-side and interpreted language, but it is also used as a general-purpose programming language. There are over 50 million domains around the world that are based on PHP, which makes it the first and most popular web application language.

PHP is a scripting language created to develop interactive and dynamic web pages; this language is written in C++, the high-level programming language.

It is so easy to write a function or a class inside the web pages and then include each other on one page. The server will execute them in a few moments as one snippet without any problem.

Anyway, to write web applications with PHP on your local machine, you just need to install a PHP server on your operating system. But before you do that, we need to explain the PHP history and how the interpreter was working.

The first release for PHP was in 1994 under the name PHP/FI, designed by Rasmus Lerdorf. He wrote this version to monitor and track the visitors who were reading his online resume.

The translator at this time was not known as an interpreter; it was only a small program that translates a few letters and numbers.

In the following year, PHP was known as Personal Home Page Tool because the changes were in the translator to read and translate a number of utilities, special instructions, and counters for the basic home page. At this time, the parser name was PHP/FI version 2.

The FI was designed in 1995; it stands for Form Interpreter, and that was another package that was combined with the Personal Home Page Tool to parse the HTML form data.

Then he added another package to allow the parser to interact with the database, its name being mSQL.

PHP/FI was in hot demand in 1997; the total number of websites that were using it was 15000, and the number was increasing bit by bit until it reached 50000.

Over the following years, PHP became more popular than any other programming language in web development.

Currently, PHP is using an advanced interpreter designed by the Zend Company, whose name is “Zend Engine”.

Superficially, at least you understood some tasks for the old PHP parser in the previous history, but the question is, how do the other programming languages work? And here, to expose that, I have to explain the difference between the interpreter and the compiler. Let’s move onto it.

Understanding the Differences Between the Interpreter and the Compiler

On either side, the compiler and the interpreter are programs that take the source code or the human language of the high-level programming language and convert it to binary bits (1s and 0s)—the machine language.

The two have the same task, which is generating the binary code, which is the machine language to be understood by the computer.

But there are some differences between them. Let’s understand each one.

The interpreter program translates the source code line by line as one statement. On the other hand, the compiler translates the full source code into one piece.

Any translator has a thing called lexical analysis to analyze the source code before translating it. So the interpreter doesn’t take time to do the lexical analysis for the source code, but the overall time is slower than the compiler.

But the compiler takes a while to do the lexical analysis for the source code, and the overall time is faster than the interpreter.

Editing the Source Code during the execution

As I mentioned, the overall execution in the interpreter is slower than in the compiler, but it allows the developers to edit and update their code during the execution process.

On the contrary, you will not be able to update the source code during the process until you stop the program.

In the code-executing phase, the interpreter will never stop if there is an error in the source code.

On the contrary, the compiler will terminate the execution phase immediately if it finds an error in the source code.

The interpreter doesn’t save the binary-bit file in disk storage. But the compiler already saves this file in disk storage.

The compiler is affecting the memory more than the interpreter. If the device doesn’t have more efficient components, especially the memory, that will affect the machine’s performance and capabilities.

In the previous section, I explained the differences for each one, but our question is, does the interpreter of the PHP programming language work as well as in the previous discussion?

The answer of this question is yes, and we are going to cover everything related to all stages of the PHP interpreter in-depth.

As I discussed in the PHP history overview, the interpreter of PHP was a small parser, its task was to read and analyze numbers and some of the small instructions.

In the following years, the interpreter program was developed, and currently, it is stronger than its first appearance.

The name of the PHP interpreter is “Zend Engine”, and here we are going to explore the phases in-depth to see how the interpreter translates the PHP source code with examples.

The first phase is lexical analysis, and its task is, to generate the sequence of tokens. Here we will see how the lexical phase analyzes the PHP source code with an example.

Then we will dive more into the following phase, which is called the parser, to see the Zend Engine VM tasks.

Also, we will see what is happening in the compilation step to generate the AST. And then the execution stage.

So, let’s focus on each one for a few moments.

The duty of this phase is tokenization or lexing, which is to receive the source code from the web server and then delete all whitespaces from the PHP code, remove all comment syntaxes and then convert all characters inside the source code into a sequence of tokens.

Actually, this stage doesn’t produce errors because its mission is lexing or tokenizing. But in general, If the compiler found an error in the source code during this phase, it will terminate this process immediately.

On the contrary, the PHP interpreter will throw an error without stopping this phase.

Let’s see how the lexical analysis works on the following PHP example.

In the previous PHP example, you will see whitespaces and lines in the source code, and there is also a PHP comment syntax.

Once the lexical analysis starts, it will remove all unneeded characters like comments, and spaces and convert the other source code characters to a sequence of tokens.

Before applying the tokenization to the previous PHP code, we just need to clarify the common token names in this phase.

Let’s see that with our previous PHP code.

Firstly, the lexical analysis searches for all the previous common tokens and sets them in a sequence. Like the below table.

Let’s see the final result for the sequence of tokens.

In the previous section, you saw the final result of the sequence of the lexical tokens. So each line in this sequence contains characters from the main source code, and each string has a token name like in the previous table.

Once the lexical analyzer finishes the task, it ignores the comment lines and sends the sequence of tokens to the following phase, which I name the heart of the interpreter. Let’s move on to the next phase.

In this phase, the parser receives the sequence of tokens and sends an order to init the Zend Engine VM&nbsp;(the virtual machine), which has the same job of the assembly language. And according to these VM instructions, the parser starts to manipulate the sequence of lexical tokens that were already been received during the previous phase.

In the previous section, we succeeded in generate a sequence of lexical tokens. Now we need to pass these characters to the parser.

Actually, there is another step in the parser, called the compilation to see what is happening there, we just need to move on to the next stage.

As I mentioned before, this phase already works within the parser – Let’s see the compilation process.

In this phase, the parser takes the manipulated lexical tokens and generates the AST (Abstract Syntax Tree ), which is building and performing the structures with nodes, each of which has a piece according to the characters that are already displayed in the lexical tokens.

The compilation stage has to pass the AST into the code generator to produce intermediate codes that are known as the OP Codes or Operation Codes, which are the machine language ( or the machine code ) – that already depends on the Zend Engine VM.

These OP Codes have three operands, one for the outputs and two for the inputs. These three operands have a list of instructions, which are complicated missions that require the execution of flow control.

Once the executor receives the OP Codes, it starts to execute and read them according to the list of the array instructions.

The last two phases (the compilation and The execution) have two direct functions in the Zend engine to do their missions. They are the&nbsp;zend_compile&nbsp;and the&nbsp;zend_execute.

Once the executor is finished with the OP Codes, it produces the final results and sends them to the web browser.

The following mission of the web browser is to render them within the HTML markups.

From this point, we are going to explain another concept regarding HTML data rendering, Let’s see the difference between a dynamic web page and a static web page.

The Difference Between the Static Web Page and the Dynamic Web Page

The static web page can only show previously prepared data using HTML structure and it can be changed only if the developer changes the page structure and contents using HTML development.

On the contrary, a dynamic web page can change the information and contents of its page according to the incoming data from a database using any programming language which can display different information for different users.

Let’s see how to write a PHP program to see the dynamic web page contents.

In this PHP program, we need to generate unique characters which should contain a group of letters, numbers, and symbols.

Every time you load the page, these characters should be changed, which means it shouldn’t have the same value as the previous page.

But before doing that, you have to make sure that you have installed the PHP package on your operating system. If it doesn’t exist, you can&nbsp;<a href="https://flatcoding.com/tutorials/php-programming/install-php-server-and-mysql/" target="_blank" rel="">install PHP</a>&nbsp;first and go back here again.

Currently, I am using a wamp server on my local machine, and my operating system is windows – You can install it through this&nbsp;<a href="https://flatcoding.com/tutorials/php-programming/install-php-server-and-mysql/" rel="" target="_blank">link</a>,

Accordingly, we just need to know what the Wamp word means.

The Wamp server contains more than one package. Each letter inside the WAMP word refers to a package name. Let’s see how many packages are inside the Wamp Server.

Montasser Mossallem

PHP is a programming language. Specifically, it's a server-side scripting language widely used for web development. How does it work?...

What is PHP? The PHP Programming Language Intro

PHP Intro

/Root

PHP Tutorial

In this tutorial, you will learn more about the history of PHP and its evolution over the years.

Let’s get started with the PHP/FI interpreter version.

The history started with the first release of PHP. Which was created in 1994 under the name PHP/FI, designed by Rasmus Lerdorf.

This version of PHP was released as “Personal Home Page” to monitor and track the visitors who were reading his online resume. Initially, the PHP compiler was named PHP/FI, which stands for Form Interpreter.

It laid the groundwork for PHP as we know it today, emphasizing ease of use and access to databases, which was a revolutionary concept at the time.

In 1995, version 2 of PHP was released. It could work with databases, helping to build complicated websites.

Let’s move into the following version of PHP in the next section.

It wasn’t until 1998, when PHP 3 came out, that PHP really went worldwide. Andi Gutmans and Zeev Suraski worked together on developing it.

They released the first version of the “Zend Engine” interpreter. It increased speed and expanded the feature set of PHP, cementing its place as a cornerstone of web development.

Anyway, in the following section, you will learn more about the subsequent version, which is PHP 4. Let’s move on.

The introduction of PHP 4 in 2000, which used Zend Engine 1.0 to improve performance, further polished the language.

The addition of features like output buffering, session management, and a more comprehensive extension API greatly enhanced its capabilities.

With this version, PHP’s status as a vital tool for building dynamic websites that update or change without a hitch was cemented as its popularity skyrocketed.

In the next section, we will delve into additional details about the subsequent version of PHP 5.

PHP 5, launched in 2004 and was a big step up. It brought in Zend Engine II with a new way to handle objects and made PHP faster and safer.

This version focused on making PHP good at object-oriented programming (OOP), which means PHP could do more things and let people build bigger, better, and easier to fix apps.

Let’s move onto the following PHP version, which is PHP 7 in the section below.

PHP continued to expand and change. The release of PHP 7 in 2015 was highly anticipated. It greatly improved the speed and usability of PHP.

You could now specify to PHP the kind of data you were working with (text or numbers), find errors more quickly, and take advantage of nifty new tools and shortcuts that made writing easier.

In this tutorial, we explored the history of PHP

PHP has gone a long way since its inception in 1994. Rasmus Lerdorf was the person who created it back then. He wanted to keep track of who visited his website. This modest notion grew into something much bigger, known as PHP/FI, which was PHP’s initial step.

PHP improved gradually over time. In 1995, it could interact with databases, which was useful for having websites do more. Then, in 1998, PHP 3 was released, and it became widely popular across the world. This version was quicker and more capable due to something known as the Zend Engine.

Fast forward to 2000, PHP 4 arrived. It was even better and made websites work smoothly. It could remember users and had new tools for developers.

PHP did not end there. PHP 5 debuted in 2004 with new programming methods that improved speed and security. Then, in 2015, PHP 7 arrived, making things far quicker and more user-friendly.

Each version of PHP strengthened and improved its suitability for website development. It’s fascinating to see how PHP evolved from a simple tool to one that drives so many websites today. So, let’s keep studying and see what happens next with PHP!

PHP started in 1994 with PHP/FI by Rasmus Lerdorf. It evolved from simple tracking to robust web development, with major updates.

PHP History: Over a Quarter-Century of Innovation

PHP History

In this tutorial, you will learn how to install PHP Server on Windows, Linux, and macOS. And install MySQL and PHPStorm IDE of PHP Applications.

PHP is a scripting open-source language created to develop web applications. There are over 50 million domains in the world that are based on PHP and that makes it the most popular web application language.

Normally, there are many server applications that save your time. They are including all tools and extensions you will use with PHP like MySql, PHPMyAdmin, Apache HTTP Server, and some other tools. These applications like WampServer and Xampp.

WampServer is an environment designed to help users to create their web applications on their local machine using the Windows operating system. WAMP word means Windows Apache Mysql PHP the all collected together on only one install.

To install the wamp on windows you need first to navigate to the wamp&nbsp;<a href="https://www.wampserver.com/en/" target="_blank" rel="noreferrer noopener nofollow">official page</a>.

Here we have to download the installation by clicking on the proper button according to your window system type ( bits64 or 32) of the above image.

It will show you a popup box containing warning messages and an empty form. Don’t worry about these messages you only have to click on the download link (&nbsp;you can download it directly&nbsp;).

The installation is being downloaded, once it finished double-click and you have to start the following step by step.

In the above image, you have to select the language of wamp installation. Then it will show you the license agreement screen just accept it and click on the Next button.

The next step it will show you some information about wamp just click on the Next button.

Then it will ask you, what is the destination location for this installation. We advise you to remain on the default path.

In the next step, the program will show you another screen containing all components of the wamp installation you just have to choose the needed versions of each package and there are some default components that are being installed directly with the software package like apache, default PHP version and so on.

The next step will show you another screen that asks you to select the start menu folder location and just remain the current default option.

Here will show you the final screen of the installation containing a summary of options you made before, just click on the install button.

Once the installation is finished just click on the finish button.

If you faced any problem you just have to ensure that your machine has the following needed apps besides the wamp :

To start a new PHP project in the wamp. Firstly you have to play all services on the wamp like apache, PHP, and MySql. And to do that follow the below steps.

Click on the windows start menu search about wamp and play it. To make sure that all services already started. In the taskbar with your right hand, there is a small arrow once you open it you will see a wamp icon just click on it

It shows you a green color icon, this means all services are working correctly. and if you need to restart the wamp click on this green icon it will show you the wamp menu that contains all services.

In the next step, we have to create our PHP project. Do you remember where did we install the location of the wamp server? It is in the C:/ partition if you scroll up to the location screen you will find the right path of it&nbsp;C:\wamp64.

Inside this folder, we have to navigate to the&nbsp;www&nbsp;folder, and here we can create our first project folder with PHP.

As you saw in the previous image, we created a&nbsp;test&nbsp;folder for our PHP project and inside it, we created&nbsp;index.php&nbsp;file containing the below code.

To see the PHP code result, open your browser and navigate to this URL “localhost/site“. Actually, when you load the page there are some processes that happen behind the scene to interpret the PHP source code.

Install PHP and MySQL using the Xampp Server

Before we explain how to install XAMPP we just need to define what are XAMPP stands for? the letters inside the XAMPP word mean “Cross-Platform (X), Apache HTTP Server (A), MySql (M), PHP (P), Perl (P)“. It is an environment that helps us to create a local web server on our machine.

To install XAMPP follow the below steps one by one.

Open your browser and go to this URL&nbsp;<a href="https://www.apachefriends.org/" target="_blank" rel="noreferrer noopener nofollow">apachefriends.org</a>, the next step you have to select the proper installation according to your operating system. It can work on Windows, macOS, and Linux.

Once the download is being finished double-click on the installer

The program will show you a welcome screen like the below image, you have to click on the Next button.

The next screen will show you the program components, just remain the default choices and click on the Next button

In the next step, the program will show you the next screen containing the installation location just select a new path for the installation or remain the default path.

It will show you on the next screen an option to select the application language. select it then click on the Next button.

Once you moved to the next screen, it will show you an optional about if you like to install bitnami for XAMPP. just click on the Next button. Then on the final screen also click on the Next button to start the installation.

In the final step, in the completing screen, just click on the finish button.

Your PHP projects should be created in the “htdocs” folder. you can find it in this path in your machine “C:\xampp\htdocs“. Then you can see the result using your browser “localhost/…“.

Here is the final image showing you the XAMPP Control Panel that and you can start or stop any of the services as you like.

On Linux, we can use the previous XAMP program to install the PHP environment. But some other developers like to install the PHP using the terminal. And to do that you have to install all other tools as a lone like Apache, MariaDB, MySQL, PHPMyAdmin, and so on.

In this section, we only go to install PHP and Apache HTTP Server if you like to know more about the other tools just install LAMP.

Firstly, to install the apache server you have to use the below commands.

In the next step, open your browser and navigate to&nbsp;localhost&nbsp;you should see a web page like the below image.

To restart the apche2 HTTP server use one of the below commands

The next setup will be the PHP scripting language installation. Just run only the below commands to install it

The previous command will install the latest version of PHP. But if you need to install the old version just put the version number beside the PHP word.

To install MySQL use the following command through the ubuntu terminal.

To install the PHP package on your macOS machine you need to use&nbsp;<a href="https://brew.sh/" target="_blank" rel="noreferrer noopener nofollow">homebrew</a>. If you don’t have it just run the command in the&nbsp;<a href="https://brew.sh/" target="_blank" rel="noreferrer noopener nofollow">brew.sh</a>&nbsp;according to the instructions there.

In the next step, we need to install the PHP package using the brew command.

And to install MySQL use the following command.

PHPStorm is created by JetBrains, to download it navigate to&nbsp;<a href="http://www.jetbrains.com/phpstorm/download/" target="_blank" rel="noreferrer noopener nofollow">JetBrains</a>&nbsp;and download the product according to your operating system. They support Windows, macOS, and Linux.

Once you download it just click two times on the app, and the program will start the installation with the welcome screen. Then click on the Next button.

The next screen asks you to choose the install location. If you don’t need to choose a path for the installation just remain it with the default location. And click on the Next button.

And then the program will show you options to choose from. Like if you need to create a shortcut from the program on your desktop, Update the context menu, and so on.

Once you click on the next button it will show you the final screen containing a summary of the selected options. Just click on the install button.

On the final screen, check on “Run PHPStorm” and click on the finish button. It will show you terms agreement. Just check on it and then click on the continue button.

And finally congratulations, it is ready.

XDebug is an extension created for PHP to help developers to profile and debug the capabilities during the development stage.

To install XDebug navigate to the&nbsp;<a href="https://xdebug.org/download#releases" target="_blank" rel="noreferrer noopener nofollow">official page</a>&nbsp;to learn more about the installation guide.

Before downloading the XDebug we need to know what is the version already installed in the local web host for PHP. In this case, our current PHP version is&nbsp;<code>7.4.26</code>

So we need to download the compatible version for our PHP.

To install the PHP server and MySQL download the XAMPP or wamp for windows, use sudo apt install PHP mysql for ubuntu, or use brew install php mysql for mac.

How to Install the PHP Server and MySQL

Install PHP

The PHP tag, or syntax, is a set of rules and guide lines for PHP code. Therefore, when writing code in PHP, you have to follow it; otherwise, the interpreter will ignore the code execution.

Before getting started, it is essential to know that the file name of a PHP document ends with “.PHP” as an extension.

Actually, there are many types of PHP tags, which are:

Anyway, let’s move onto the following section to understand how the default tag work in PHP.

Opening and closing tags in PHP are similar to “hello” and “goodbye” in a conversation. So on computer, you have to start the document with “&lt;?php” and close it with “?&gt;”.Between these two syntaxes, the PHP blocks.

You can also open the PHP code with the “&lt;?php” syntax and keep it open without a closing tag. However, you need to use a semicolon “;” at the end of each line.

Additionally, you can write the last line within a PHP script without a semicolon, but in this case, you must use the closing tag. Otherwise, it will display a syntax error.

Anyway, PHP also supports shorthand echo. Let’s move into the following section to understand how it works.

The shorthand echo is a quicker way to print or display data in PHP. So, when you want to show something on the webpage, you have to write the word `echo` followed by the data or variable. But the shorthand echo can perform this task more swiftly.

Observe the standard echo in PHP, which can be written as shown in the code below.

This can be written in shorthand, as shown below:

So, you can use this syntax when mixing PHP code with HTML. It also makes the code cleaner and easier to read.

However, remember that this shorthand only works if your PHP settings (specifically&nbsp;<code>short_open_tag</code>&nbsp;) allow it.

Anyway, let’s move on to another pattern for short tags in PHP, which also depends on the PHP setting&nbsp;<code>short_open_tag</code>.

PHP short tag is a shorter version of PHP standard opening tags.

PHP syntax ( tags ) is key in PHP scripting. It includes standard open/close tags, short tags, and shorthand tags for coding. For Example...

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