PHP Fundamentals: A Comprehensive Introduction

PHP Fundamentals:
A Comprehensive
Introduction
Nilesh Valva

Introduction
PHP (Hypertext Preprocessor) is a popular open-
source scripting language especially suited for web
development. It can be embedded in HTML and is
widely used to create dynamic web pages.

Key Features of PHP
● Server-Side Scripting: PHP scripts are executed on the server.
The client receives the output, which is usually HTML, rather
than the PHP code itself.
● Cross-Platform: PHP runs on various platforms (Windows,
Linux, Unix, Mac OS) and interfaces easily with different web
servers like Apache and IIS.

● Ease of Use: PHP is designed to be simple for beginners but offers many
advanced features for professional programmers.
● Embedded in HTML: PHP code can be embedded directly within HTML
code, which simplifies the creation of dynamic content.
● Database Integration: PHP has built-in support for working with databases,
including MySQL, PostgreSQL, Oracle, and many others.
● Wide Range of Libraries: PHP has a rich set of built-in functions and
extensions, as well as a large repository of third-party libraries.

Setting Up the Environment
Installing PHP
Setting up a local server with XAMPP or MAMP

Basic PHP Syntax
PHP code is usually written inside <?php ... ?> tags within an HTML
document.

Here’s a simple example:
<!DOCTYPE html>
<html>
<head>
<title>My First PHP Page</title>
</head>
<body>
<h1><?php echo "Hello, World!"; ?></h1>
</body>
</html>

Variables and Data Types
PHP supports various data types, including strings, integers, floats,
arrays, objects, and more. Variables in PHP are prefixed with a $
sign.

Here’s a simple example:
<?php
$name = "First Name"; // String
$age = 30; // Integer
$height = 5.9; // Float
$is_student = true; // Boolean
echo "Name: $name, Age: $age, Height: $height, Is Student: $is_student";
?>

Control Structures
Control structures in PHP allow you to control the flow of your
program based on certain conditions and repeatedly execute blocks
of code. These include conditional statements, loops, and include
statements. Here’s an overview of the main control structures in
PHP:

● Conditional Statements
○ if Statement
○ if...else Statement
○ if...elseif...else Statement
○ switch Statement
● Loops
○ while Loop
○ do...while Loop
○ for Loop
○ foreach Loop
● break and continue
○ break is used to exit a loop or switch statement.
○ continue is used to skip the current iteration of a loop and proceed
to the next iteration.

● Include Statements
○ Include: Includes and evaluates the specified file. If the file is not
found, it gives a warning but the script continues.
○ require: Includes and evaluates the specified file. If the file is not
found, it gives a fatal error and stops the script.
○ include_once and require_once: Includes the specified file only once,
even if called multiple times. This is useful for including files with
functions or classes to avoid redeclaration errors.

Object-Oriented Programming
Object-Oriented Programming (OOP) in PHP is a programming
paradigm that uses objects and classes to create modular, reusable
code. PHP has supported OOP since version 5, and it provides a rich
set of features for developing robust and maintainable applications.

Key Concepts of OOP in PHP
Classes and Objects:
● Class: A blueprint for creating objects (a particular data
structure), containing methods and properties.
● Object: An instance of a class.

Properties and Methods:
● Properties: Variables that belong to an object.
● Methods: Functions that belong to an object.
Visibility:
● public: The property or method can be accessed from anywhere.
● protected: The property or method can be accessed within the class
and by classes derived from that class.
● private: The property or method can only be accessed within the class.

Inheritance: A class can inherit properties and methods from another class.
Polymorphism: Methods can be overridden in derived classes to provide
specific implementations.
Encapsulation: Keeping the internal state of an object hidden and only
allowing access through public methods.
Abstraction: Abstract classes and interfaces provide a way to define
methods that must be implemented by derived classes.

<?php
class Person {
public $name;
private $age;
public function __construct($name, $age) { // Constructor
$this->name = $name;
$this->age = $age;
}
public function greet() { // Method
return "Hello, my name is " . $this->name . " and I am " . $this->age . " years old.";
}
public function getAge() { // Getter for private property
return $this->age;
}
public function setAge($age) { // Setter for private property
if($age > 0) {
$this->age = $age;
}
}
}
?>

Creating Objects
<?php
// Include the class definition
require_once 'Person.php';
// Create an object of the Person class
$person1 = new Person("Alice", 30);
echo $person1->greet(); // Output: Hello, my name is Alice and I am 30 years old.
$person2 = new Person("Bob", 25);
echo $person2->greet(); // Output: Hello, my name is Bob and I am 25 years old.
?>

PHP frameworks
PHP frameworks provide a structured foundation for building web
applications by offering reusable libraries, components, and tools.
They help developers write clean, maintainable code and speed up
the development process. Here are some popular PHP frameworks:
Laravel, Symfony, CodeIgniter, CakePHP, Zend Framework /
Laminas etc..

Conclusion
PHP is a versatile language that can be used for a wide range of
web development tasks, from simple scripts to complex web
applications. Its ease of integration with HTML and databases,
along with a large community and extensive documentation, make
it a valuable tool for web developers.

PHP Fundamentals: A Comprehensive Introduction

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