PHP & Laravel Quick Revision: Data Types, OOP, MVC, Composer, and Best Practices

This guide will help you quickly revise PHP basics, OOP concepts, MVC, Composer, and modern best practices.

PHP Basics Refresher

🔹 Data Types in PHP

PHP supports 8 main data types:

String → "Hello"
Integer → 10
Float/Double → 10.5
Boolean → true / false
Array → [1, 2, 3]
Object → instance of a class
NULL → no value
Resource → special types (DB connection, file handles)

🔹 Loops in PHP

for → fixed iterations
while → runs while condition is true
do…while → runs at least once, then checks condition
foreach → loops arrays/objects

🔹 NULL vs Empty

NULL → no value at all.
Empty → value exists but is considered empty ("", 0, false, [], null).
👉 All null are empty, but not all empty are null.

🔹 Arrays

Indexed array → numeric keys
Associative array → string keys
Multidimensional array → arrays within arrays

🔹 Type Casting vs Type Juggling

Type Casting → manual conversion: (int)"10"
Type Juggling → PHP auto-converts when needed: "10" + 5 = 15

⚠️ Juggling can be risky. Protect against it by:

Using strict comparison ===
Enabling strict typing: declare(strict_types=1);

🔹 Error Control Operator

@ suppresses errors: $file = @file("missing.txt");
⚠️ Bad practice — instead use try...catch.

Writing Professional PHP Code

Some best practices every PHP developer should follow:

Enable strict types
Use try…catch for error handling
Use Composer for packages & autoloading
Use require_once instead of require
Follow PSR standards (PSR-1, PSR-4, PSR-12)
Use namespaces
Organize code with OOP & MVC
Validate and sanitize input
Use prepared statements/ORM for DB
Store configs in .env files
Use dependency injection instead of globals/singletons

Dependency Injection (DI) in PHP

Without DI: A class creates its own dependencies.
With DI: Dependencies are provided externally (constructor/method).

👉 Example:

class OrderService {
    private $db;
    public function __construct(Database $db) {
        $this->db = $db; // injected
    }
}

Benefits: loose coupling, testability, easier maintenance.
Laravel handles DI automatically via its Service Container.

PDO vs MySQLi

MySQLi → works only with MySQL.
PDO → works with multiple databases (MySQL, SQLite, PostgreSQL, etc.).
Laravel uses PDO by default.

Switch vs Match

switch → loose comparison, needs break.
match (PHP 8+) → strict comparison, returns value, no break.

Example:

echo match($x) {
    1 => "One",
    2 => "Two",
    default => "Other",
};

Variadic Functions

A variadic function accepts any number of arguments using ....

function sum(...$numbers) {
    return array_sum($numbers);
}

echo sum(1,2,3,4); // 10

Final Thoughts

PHP remains a solid backend choice, especially when paired with Laravel. By following PSR-12 standards, dependency injection, and Composer, you can write clean, professional, and maintainable code.

Modern PHP (with features like match, variadic functions, and strict types) is far more powerful than its old reputation suggests. Combine this with Laravel’s ecosystem, and you’re ready for both small apps and enterprise-level systems.

Let’s start with OOP principles.

There are 4 main principles of OOP (easy to remember with A PIE):

A → Abstraction
- Show only essential details, hide complexity.
- Example: You use car->start() without knowing how engine works.
P → Polymorphism
- One function/method can behave differently depending on context.
- Example: draw() works differently for Circle and Square.
I → Inheritance
- Child class gets properties & methods from parent class.
- Example: Dog inherits from Animal.
E → Encapsulation
- Bundle data & methods together, restrict access with public/private/protected.
- Example: Bank balance can’t be changed directly, only via deposit() method.

👉 Memory Trick:
Think of OOP as eating “A PIE” 🍰 → Abstraction, Polymorphism, Inheritance, Encapsulation.

✅ That’s your revision summary blog post for today!