PHP Programming Overview

What is PHP?

• PHP stands for Hypertext Preprocessor, a server-side scripting language used for web development and as a general-purpose programming language.
• PHP code is executed on the server, generating HTML that is sent to the client's web browser.

History of PHP

• PHP was created by Danish-Canadian programmer Rasmus Lerdorf in 1994.
• The first version of PHP, named PHP/FI (Personal Home Page/Forms Interpreter), was released in 1995.

Key Features of PHP

• Open Source: PHP is freely available and actively maintained by a vast community of developers.
• Cross-platform Compatibility: PHP runs on various operating systems like Windows, Linux, macOS, etc.
• Server-side Scripting: PHP scripts are executed on the server, producing dynamic content that can be sent to the client's browser.
• Database Integration: PHP supports integration with various databases like MySQL, PostgreSQL, SQLite, etc.
• Extensive Library Support: PHP offers a rich set of built-in functions and extensions for various tasks such as string manipulation, file handling, networking, and more.

Difference between PHP and Client-side Scripting Languages

• PHP is executed on the server, whereas JavaScript runs on the client's browser.
• PHP generates dynamic content on the server before sending it to the client, while JavaScript manipulates the content already rendered in the browser.
• PHP is primarily used for server-side processing and interacting with databases, while JavaScript is used for client-side interactivity and validation.

PHP Frameworks

• Laravel, Symfony, CodeIgniter, Yii, and Zend Framework are popular PHP frameworks.
• These frameworks provide pre-built modules and libraries to streamline the development process, improve code organization, and enhance security.

Connecting PHP with a Database

• PHP can connect to various databases using database-specific extensions or APIs.
• For example, to connect to a MySQL database, you can use the mysqli or PDO extension in PHP.

Embedding PHP Code within HTML

• PHP code is embedded within HTML using special delimiters: <?php ?>
• For example: <?php echo "Hello, World!"; ?>

PHP Variables

• A variable in PHP is a placeholder for storing data values.
• Variables are preceded by a dollar sign ($) followed by the variable name.
• PHP variables are case-sensitive and must begin with a letter or underscore, followed by letters, numbers, or underscores.

PHP Data Types

• Integer: Represents whole numbers, both positive and negative, without decimal points.
• Float (or Double): Represents numbers with decimal points or numbers in exponential form.
• String: Represents sequences of characters, such as text.
• Boolean: Represents either true or false.
• Array: Represents a collection of key-value pairs or an ordered list of values.
• Object: Represents instances of classes, allowing for object-oriented programming.
• NULL: Represents a variable with no value.

PHP Comments

• Single-line comments: Single-line comments start with // and extend to the end of the line.
• Multi-line comments: Multi-line comments start with /* and */ and can span multiple lines.