PHP: Introduction

Introduction to PHP:

Let’s begin with the introduction to PHP.

Applications of PHP:

PHP is a server-side scripting language that allows you to create dynamic web pages. That is, PHP enables you to use web server scripts to generate customized responses for each client’s (user’s) request.

PHP is the backbone of:

  • Several CMS are available (WordPress, Drupal, Joomla)
  • Platforms for E-Commerce (WooCommerce, Magento)
  • Frameworks for Web Development (Laravel, CakePHP, Symfony)

Terminating a PHP Statement:

A semicolon ; must use to end a statement in PHP.

Because whitespace can usually ignore, ignoring a semicolon at the end of a statement causes PHP to assume that the next statement is part of the current one. So, it might result in errors.

// Three statements, all with their own ;
echo "Jim";
echo "Alex";
$var1 = "Hello";

PHP Keyword Case-Insensitivity:

if, else, null, echo, foreach, or other language keywords are not case sensitive in PHP.

For example, the words Echo and echo are interchangeable. Using the same casing as when the keyword or function was defined is, however, a good practice.

Constants, variables, array keys, class constants, and class properties, on the other hand, are case-sensitive.

echo "Hello";
Echo "Hello";
//Both the above lines are correct in PHP
 
$var1 = 2;
$Var1 = 4;
// These are two different variables in PHP

PHP Comments:

Comments are lines of code that aren’t executed when the program is run.

Comments can use to explain how code works and to leave notes for other developers. PHP allows for both single-line and multi-line comments.

The syntax for single-line comments is // or #. Hence the PHP interpreter ignores anything after these symbols on a line.

The interpreter ignores everything between /* and */ in multi-line comments.

echo "Hello";
 
// This is a single-line comment. This line is ignored by PHP.
 
# This is also a single-line comment. This line is also ignored by PHP.
 
/* This is a multi-line comment.
   everything in between these two comment 
   delimiters is ignored by PHP. */

Dynamic Webpages using PHP:

PHP is a server scripting language. This server-side code can use to populate HTML templates, resulting in a completely functional HTML document for a visitor. A dynamic webpage is the name given to the completed document.

Unlike static pages, which give the same collection of materials to everyone, dynamic PHP webpages can deliver a custom set of assets to each visitor.

PHP Script Execution:

The PHP can provide in such a way that it can execute by any browser that connects to the server.It refers to server-side scripting.

PHP scripts can run on demand from the terminal, and the script’s output can log to the terminal. Scripting on the command line can refer to as command-line scripting.

PHP Code Embedding:

When a file with .php extension is saved, PHP can generate HTML. These files must always start with the tag <?php  (closing tag is optional).

PHP can also embed into HTML. Both the opening tag <?php and the closing tag ?> can use in this case.

The PHP code, for example, has been embedded into the HTML in the given code by enclosing it within the <?php and ?> tags.

<html>
  <body>
    <?php
      echo "Hello World!";
      ?>
  </body>
</html>

PHP echo Keyword:

If output is being served, the echo keyword in PHP is used to write it to the browser.

If the command is run from the command line, the echo keyword prints the output to the terminal.

echo "Hey, how are you?"

Helpful Tools:

Here are some useful tools to help you along your journey!

Setting up an IDE (Integrated Development Environment) can be difficult for beginners. The Online Compiler will enable you to run your code inside your browser without the need to install an IDE. If you need a more detailed explanation of a specific topic, the best place to find answers is in the Official Documentation.

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