1. Just-In-Time (JIT) Compiler

The biggest feature of PHP 8 is the Just-In-Time (JIT) Compiler. It improves performance, especially for CPU-intensive tasks. JIT compiles PHP code into machine code at runtime, resulting in faster execution.

👉 While improvements in web applications are limited, JIT is highly noticeable in heavy calculations, image processing, and complex data handling.

2. Union Types

PHP 8 allows multiple types to be specified for function or method arguments and return types.

function test(int|string $value): int|string {
    return $value;
}
    

3. Named Arguments

You can now pass values to a function by specifying the parameter name directly, improving readability and allowing you to skip optional parameters.

function userProfile($name, $age, $email) {}

userProfile(
    name: "Avinash",
    email: "avinash@gmail.com",
    age: 25
);
    

4. Attributes (Annotations)

Previously, annotations in PHP were implemented using comments (/** ... */). In PHP 8, the #[Attribute] syntax was introduced.

#[Route("/home", methods: ["GET"])]
function homePage() {}
    

5. Constructor Property Promotion

Class properties and constructor assignments can now be written in a single line, reducing boilerplate code.

class User {
    public function __construct(
        public string $name,
        public int $age
    ) {}
}
    

👉 Previously, you had to separately declare properties and assign them in the constructor.

6. Match Expression

A modern and safer alternative to the switch statement.

$status = 2;
$message = match($status) {
    1 => "Pending",
    2 => "Approved",
    3 => "Rejected",
    default => "Unknown"
};
    

7. Nullsafe Operator (?->)

A shortcut for null checks when accessing chained properties or methods.

$country = $user?->getAddress()?->getCountry();
    

👉 If $user or getAddress() is null, it returns null instead of throwing an error.

8. Stringable Interface

Any class that implements the __toString() method will automatically implement the Stringable interface.

function printData(Stringable $obj) {
    echo $obj;
}
    

9. New String Functions

• str_contains("Hello World", "World") → true
• str_starts_with("Hello", "He") → true
• str_ends_with("Hello", "lo") → true

10. Consistent Type Errors

In PHP 8, type mismatches now throw a TypeError instead of generating warnings.

11. Throw Expression

You can now use throw inside expressions.

$value = $input ?? throw new InvalidArgumentException("Input required");
    

12. Weak Maps

The WeakMap was added in PHP 8, allowing objects to be referenced without preventing garbage collection.

$map = new WeakMap();
$obj = new stdClass();
$map[$obj] = "data";
    

⚠️ Deprecations and Breaking Changes

• create_function() removed
• is_real() removed
• each() function removed
• Magic quotes / Safe mode / Register globals were already removed in PHP 7.x
• Resources (GD, Sockets) converted into objects
• @ error suppression adjusted for performance
• Engine warnings and notices are now more consistent and strict

👉 Summary

• Performance boost (JIT + engine improvements)
• Modern language features (match, attributes, nullsafe, union types, named arguments)
• Developer productivity significantly improved
• Old/unsafe functions removed to make PHP cleaner