Are you still using PHP 5 or an older PHP 7 version? Upgrading to PHP 8 is a game-changer! With massive performance improvements, enhanced security, and powerful new features, PHP 8 is the best version yet for modern web development. In this guide, we’ll break down the key differences between PHP 5 and PHP 8, explore the speed and efficiency gains, and highlight must-know features like JIT compilation, union types, and attributes. Whether you’re maintaining legacy code or building a new project, this comparison will help you understand why upgrading is worth it. Let’s dive in!
1. Performance Improvements
Difference: PHP 8 is significantly faster due to the JIT (Just-In-Time) Compiler, while PHP 5 relies on traditional interpretation.
Example:
// PHP 8 with JIT
function sum($a, $b) {
return $a + $b;
}
echo sum(5, 10);
➡ In PHP 8, JIT compiles functions to machine code, improving execution speed.
2. New Type System and Stronger Typing
Difference: PHP 8 enforces stricter type checking, while PHP 5 allowed more implicit type conversions.
Example:
// PHP 5: No strict type checkingfunction add($a, $b) {
return $a + $b;
}
echo add("5", "10"); // Outputs: 15
// PHP 8: Enforcing types
function add(int $a, int $b): int {
return $a + $b;
}
echo add("5", "10"); // Fatal error in PHP 8 if strict_types is enabled
3. Nullsafe Operator (?->)
Difference: PHP 8 introduced the nullsafe operator, which avoids errors when calling methods on null.
Example:
PHP 5: Causes fatal error
$user = null;
echo $user->profile->name; // Fatal error
PHP 8: Safe null handling
echo $user?->profile?->name; // Outputs nothing, but no error4. Match Expression
Difference: PHP 8 introduced match, which is more powerful than switch.
Example:
// PHP 5: Using switch$color = "red";
switch ($color) {
case "red":
$result = "Stop";
break;
case "green":
$result = "Go";
break;
default:
$result = "Unknown";
}
echo $result;
// PHP 8: Using match
$color = "red";
$result = match ($color) {
"red" => "Stop",
"green" => "Go",
default => "Unknown"
};
echo $result;
➡ match is faster and does strict type checking.
5. Named Arguments
Difference: PHP 8 allows passing arguments by name instead of position.
Example:
// PHP 5
function greet($name, $greeting) {
return "$greeting, $name!";
}
echo greet("John", "Hello");
// PHP 8: Named arguments
echo greet(greeting: "Hello", name: "John"); // Same output but more readable6. Constructor Property Promotion
Difference: PHP 8 simplifies class constructors by defining properties directly in the constructor.
Example:
// PHP 5: Long syntax
class User {
public $name;
public $email;
public function __construct($name, $email) {
$this->name = $name;
$this->email = $email;
}
}
// PHP 8: Shorter syntax
class User {
public function __construct(public string $name, public string $email) {}
}7. Attributes (Annotations)
Difference: PHP 8 introduced attributes (#[...]) to replace PHP 5-style annotations (@).
Example:
// PHP 5: Annotations (ignored by PHP, used by third-party tools)
/**
* @Route("/home")
*/
function home() {}
// PHP 8: Native Attributes
#[Route("/home")]
function home() {}8. Union Types
Difference: PHP 8 allows specifying multiple types for a variable.
Example:
// PHP 5: No union types
function setAge($age) {
if (!is_int($age) && !is_string($age)) {
throw new Exception("Invalid type");
}
}
// PHP 8: Union types
function setAge(int|string $age) {} 9. WeakMap Support
Difference: PHP 8 introduced WeakMap to avoid memory leaks when storing objects.
Example:
// PHP 8 Only
$map = new WeakMap();
$obj = new stdClass();
$map[$obj] = "data";10. String Functions Improvements
Difference: PHP 8 improves string manipulation functions.
Example:
// PHP 5: No str_contains
if (strpos("hello world", "hello") !== false) {
echo "Found!";
}
// PHP 8: str_contains
if (str_contains("hello world", "hello")) {
echo "Found!";
}11. Throw Expressions
Difference: PHP 8 allows throw inside expressions.
Example:
// PHP 5: Cannot throw in expressions
function checkAge($age) {
if ($age < 18) {
throw new Exception("Too young");
}
}
// PHP 8: Throw in expressions
$age = 17;
$canEnter = $age >= 18 ? true : throw new Exception("Too young");12. Trailing Comma in Function Calls
Difference: PHP 8 allows a trailing comma in function calls.
Example:
// PHP 5: Syntax error
array_map('trim', ['apple', 'banana']);
// PHP 8: Works fine
array_map('trim', ['apple', 'banana',]);13. Consistent Type Errors
Difference: PHP 8 throws TypeError instead of silent conversion.
Example:
// PHP 5: Implicit conversion
function test(int $num) {
return $num;
}
echo test("5"); // Works in PHP 5
// PHP 8: Throws TypeError
echo test("5"); // Fatal error14. Deprecated Features in PHP 8
Difference: Some PHP 5 features are removed in PHP 8.
create_function()→ Use anonymous functions instead.- Magic Quotes (
magic_quotes_gpc) → Removed. each()function → Useforeachinstead.- PHP 4-style constructors (
function ClassName()) → Removed.
15. Named Parameters in Function Calls
Difference: PHP 8 allows passing arguments by name, improving code readability.
Example:
// PHP 5: Positional arguments only
function greet($name, $greeting) {
return "$greeting, $name!";
}
echo greet("John", "Hello");
// PHP 8: Named parameters
echo greet(name: "John", greeting: "Hello");
➡ Named parameters allow skipping optional arguments without worrying about order.
16. Mixed Type
Difference: PHP 8 introduces the mixed type for functions that accept multiple types.
Example:
// PHP 8
function processData(mixed $data) {
if (is_array($data)) {
return count($data);
}
return $data;
}
➡ mixed includes int, float, string, bool, array, object, callable, and null.
17. Static Return Type
Difference: PHP 8 introduces static as a return type for better type hinting.
Example:
// PHP 8
class A {
public static function getInstance(): static {
return new static();
}
}
➡ Useful in inheritance when returning instances of child classes.
18. Non-Capturing Catches
Difference: PHP 8 allows catching exceptions without needing to assign them to a variable.
Example:
// PHP 5: Must capture the exception
try {
throw new Exception("Error!");
} catch (Exception $e) {
echo $e->getMessage();
}
// PHP 8: No need to capture the exception
try {
throw new Exception("Error!");
} catch (Exception) {
echo "An error occurred!";
}19. Improved Error Handling in Internal Functions
Difference: Many PHP built-in functions that previously returned false on failure now throw an exception.
Example:
// PHP 5: Returns false
$file = fopen("nonexistent.txt", "r"); // false
// PHP 8: Throws an exception
try {
$file = fopen("nonexistent.txt", "r");
} catch (Exception $e) {
echo "File not found!";
}
➡ In PHP 8, handling errors is now more predictable.
20. get_debug_type() Instead of gettype()
Difference: get_debug_type() provides better type descriptions than gettype().
Example:
// PHP 5
echo gettype(123); // Outputs: integer
// PHP 8
echo get_debug_type(123); // Outputs: int
➡ get_debug_type() returns better and consistent type names.
21. Stringable Interface
Difference: PHP 8 introduces the Stringable interface for classes that implement __toString().
Example:
// PHP 8
class Person {
public function __toString(): string {
return "John Doe";
}
}
function printName(Stringable $obj) {
echo $obj;
}
printName(new Person()); // Outputs: John Doe
➡ Any object implementing __toString() automatically implements Stringable.
22. preg_match() and preg_match_all() Return null on Error
Difference: In PHP 8, preg_match() returns null on failure instead of false.
Example:
// PHP 5
$result = preg_match('/[/', 'test'); // false
// PHP 8
$result = preg_match('/[/', 'test'); // null
➡ This helps distinguish between an error and a non-matching result.
23. Locale-Independent strtolower() and strtoupper()
Difference: PHP 8 makes string functions locale-independent, preventing unexpected behavior.
Example:
// PHP 5: May be affected by locale settings
setlocale(LC_CTYPE, "tr_TR.UTF-8");
echo strtolower("I"); // Might output "ı" instead of "i"
// PHP 8: Always consistent
echo strtolower("I"); // Outputs "i"
➡ No more issues with Turkish or other locale-specific letter conversions.
24. Float-to-String Conversion Changes
Difference: PHP 8 improves float to string conversion by removing unnecessary decimal places.
Example:
// PHP 5
echo (string) 1.500000; // Outputs: "1.500000"
// PHP 8
echo (string) 1.500000; // Outputs: "1.5"
➡ More natural number formatting.
25. is_countable() Function
Difference: PHP 8 provides is_countable() to check if a variable is countable.
Example:
// PHP 5
if (is_array($var) || $var instanceof Countable) {
$count = count($var);
}
// PHP 8: Easier
if (is_countable($var)) {
$count = count($var);
}
➡ Makes code more readable and less error-prone.
26. array_key_first() and array_key_last()
Difference: PHP 8 provides built-in functions to get the first and last keys of an array.
Example:
// PHP 5: Custom function needed
reset($array);
$first_key = key($array);
// PHP 8: Built-in functions
$first_key = array_key_first($array);
$last_key = array_key_last($array);
➡ Cleaner and more efficient way to get array keys.
27. Deprecation of filter_var() with FILTER_SANITIZE_STRING
Difference: The FILTER_SANITIZE_STRING filter has been removed in PHP 8.
Example:
// PHP 5: Allowed
$clean = filter_var("<h1>Hello</h1>", FILTER_SANITIZE_STRING);
// PHP 8: Deprecated, use strip_tags()
$clean = strip_tags("<h1>Hello</h1>");
➡ Security improvements by removing unreliable sanitization filters.
28. Changes in Default mbstring Encoding
Difference: PHP 8 changes the default encoding for mbstring functions to UTF-8 instead of system-dependent defaults.
Example:
// PHP 5: Default encoding was system-dependent
mb_internal_encoding("UTF-8");
// PHP 8: Default is always UTF-8
echo mb_internal_encoding(); // Outputs "UTF-8"
➡ Prevents encoding issues when working with multibyte strings.
29. fdiv() for Division by Zero Handling
Difference: PHP 8 introduced fdiv() to handle division by zero without errors.
Example:
// PHP 5: Division by zero causes a fatal error
echo 10 / 0; // Fatal error
// PHP 8: `fdiv()` returns INF instead
echo fdiv(10, 0); // Outputs INF
➡ Useful for mathematical operations that need to handle infinity.
30. get_resource_id() for Resource ID Retrieval
Difference: PHP 8 introduces get_resource_id() to retrieve resource IDs more easily.
Example:
// PHP 8$stream = fopen("file.txt", "r");
echo get_resource_id($stream); // Outputs resource ID number
➡ Makes working with resources more consistent.
31. WeakReference Class
Difference: PHP 8 introduces WeakReference to reference an object without preventing garbage collection.
Example:
// PHP 8
$object = new stdClass();
$weakRef = WeakReference::create($object);
unset($object);
var_dump($weakRef->get()); // NULL, object was garbage collected
➡ Helps manage memory more efficiently.
32. token_get_all() Now Returns Tokens as Strings
Difference: In PHP 8, token_get_all() returns simple tokens as strings instead of arrays.
Example:
// PHP 5
print_r(token_get_all('<?php echo "hello";'));
/*
Array output contains arrays:
[0] => Array ([0] => T_OPEN_TAG [1] => "<?php " [2] => 1)
*/
// PHP 8
print_r(token_get_all('<?php echo "hello";'));
/*
Simpler output with strings:
[0] => "<?php "
*/➡ Reduces unnecessary complexity in token parsing.
33. DateTime::createFromInterface() and DateTimeImmutable::createFromInterface()
Difference: PHP 8 allows easy conversion between DateTime and DateTimeImmutable.
Example:
// PHP 8
$dateImmutable = new DateTimeImmutable("2025-03-19");
$date = DateTime::createFromInterface($dateImmutable);
➡ Simplifies working with date objects.
34. json_validate() to Check JSON Validity
Difference: PHP 8 introduces json_validate() to check if a string is valid JSON without decoding it.
Example:
// PHP 8
$json = '{"name":"John"}';
if (json_validate($json)) {
echo "Valid JSON";
}
➡ More efficient than using json_decode() just for validation.
35. str_starts_with() and str_ends_with()
Difference: PHP 8 makes checking string prefixes and suffixes easier.
Example:
// PHP 5: Had to use substr()
if (substr("hello world", 0, 5) === "hello") {
echo "Starts with hello";
}
// PHP 8: Built-in functions
if (str_starts_with("hello world", "hello")) {
echo "Starts with hello";
}
if (str_ends_with("hello world", "world")) {
echo "Ends with world";
}
➡ Cleaner and more readable string checks.
36. filter_var() Now Validates Boolean Strings More Strictly
Difference: In PHP 5, filter_var() converted "false" to true, but in PHP 8, it correctly returns false.
Example:
// PHP 5
var_dump(filter_var("false", FILTER_VALIDATE_BOOLEAN)); // true
// PHP 8
var_dump(filter_var("false", FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE)); // false
➡ Prevents incorrect boolean parsing.
37. in_array() and array_search() Now Accept strict=true as Default
Difference: In PHP 8, in_array() and array_search() use strict comparison by default.
Example:
// PHP 5
var_dump(in_array("5", [5, 6, 7])); // true (loose comparison)
// PHP 8
var_dump(in_array("5", [5, 6, 7], true)); // false (strict comparison)
➡ Prevents unexpected type coercion issues.
38. Improved Handling of Negative String Offsets
Difference: PHP 8 allows negative string offsets directly without needing substr().
Example:
// PHP 5: Had to use substr()
echo substr("hello", -1); // "o"
// PHP 8: Works directly
echo "hello"[-1]; // "o"
➡ Cleaner and more intuitive.
39. GMP Objects Can Be Used Directly in Arithmetic Operations
Difference: In PHP 5, GMP objects required gmp_*() functions. In PHP 8, you can use them directly.
Example:
// PHP 5
$a = gmp_init(10);
$b = gmp_init(20);
$sum = gmp_add($a, $b);
// PHP 8
$sum = $a + $b; // Works directly!
➡ More natural arithmetic operations with GMP.
40. Changes in Error Reporting Levels (E_WARNING Instead of E_NOTICE)
Difference: PHP 8 changes some E_NOTICE errors to E_WARNING.
Example:
// PHP 5: Undefined variable generates E_NOTICE
echo $undefinedVar;
// PHP 8: Now generates E_WARNING
echo $undefinedVar;
➡ More visibility for potential issues.
41. imap Extension is Now Optional
Difference: The imap extension is no longer included by default in PHP 8.
Example:
// PHP 5: Installed by default
php -m | grep imap
// PHP 8: Must be installed manually
sudo apt install php8.0-imap
➡ Requires explicit installation if needed.
42. Removal of PHP Safe Mode and Magic Quotes (Since PHP 5.4)
Difference: PHP 5 still had safe_mode and magic_quotes_gpc, while PHP 8 has completely removed them.
Example:
// PHP 5safe_mode = On
magic_quotes_gpc = On
// PHP 8These settings no longer exist.
➡ Security improvements by removing outdated features.
Conclusion: Why Upgrading from PHP 5 to PHP 8 is Essential
PHP has evolved significantly from version 5 to PHP 8, bringing massive performance improvements, modern syntax, better error handling, and stronger type safety. With features like the Just-In-Time (JIT) compiler, union types, named arguments, match expressions, and nullsafe operators, PHP 8 provides a faster, more secure, and developer-friendly experience.
Why You Should Upgrade to PHP 8 Today
- Speed & Performance – The JIT Compiler dramatically boosts execution speed, making PHP applications significantly faster than PHP 5.
- Better Code Quality – Union types, named arguments, and constructor property promotion make your code cleaner and easier to maintain.
- Stronger Error Handling – PHP 8 replaces many silent failures with exceptions, reducing hard-to-debug issues.
- Security Enhancements – Deprecated insecure features like magic quotes,
safe_mode, andFILTER_SANITIZE_STRINGare removed. - Modern Development Practices – New features like attributes (annotations), match expressions, and
Stringablealign PHP with modern programming standards.
Is It Worth Upgrading?
If you’re still running PHP 5, upgrading is a must—not only for speed but also because PHP 5 no longer receives security updates, making your application vulnerable.
If you’re using PHP 7, the performance boost from PHP 8 (especially with JIT) and improved syntax still make it a worthwhile upgrade.
Don’t let outdated PHP slow you down! Upgrade to PHP 8 today and future-proof your applications.