The PSR-12 (Extended Coding Style Guide) builds upon PSR-1 and provides detailed guidelines for formatting PHP code, making it more readable and maintainable. It is widely adopted by PHP frameworks and projects to ensure a consistent coding style.
PSR-12 is an extension of PSR-2 and has the same goal as it, but with a more modern context and new features that follow the evolution of PHP. As PHP 7 has had many changes, the rewritten PSR-2 in a new PSR was necessary to meet all the news available in PHP 7.
1. File Structure & Encoding
- All PHP files must use UTF-8 encoding without a BOM.
- PHP files should use
<?phpas the opening tag and should not use?>at the end in pure PHP files.
✅ Correct:
<?php
declare(strict_types=1);
❌ Incorrect (Closing tag in a pure PHP file):
<?php
declare(strict_types=1);
?>
2. Namespace & Use Declarations
- The namespace declaration must be on the first line after
declare(strict_types=1). - Use statements must be placed after the namespace, grouped, and sorted alphabetically.
✅ Correct:
<?php
declare(strict_types=1);
namespace App\Controllers;
use App\Models\User;
use App\Services\AuthService;
use Exception;
❌ Incorrect (Unsorted use statements):
<?php
declare(strict_types=1);
namespace App\Controllers;
use Exception;
use App\Services\AuthService;
use App\Models\User;
3. Classes, Properties, and Methods
3.1 Class Declaration
- The opening
{must be on the same line as the class declaration. - Use one blank line before the class definition.
✅ Correct:
namespace App\Models;
class User {
private string $name;
public function getName(): string {
return $this->name;
}
}
❌ Incorrect (Braces on a new line):
namespace App\Models;
class User
{
private string $name;
public function getName(): string
{
return $this->name;
}
}
3.2 Properties
-
Visibility (
public,private,protected) must always be declared. - One property per line.
- Typed properties should be preferred.
✅ Correct:
class User {
private string $name;
private int $age;
}
❌ Incorrect (Missing visibility and multiple properties on one line):
class User {
var $name, $age;
}
3.3 Methods
- The function name must be in camelCase.
- The opening
{must be on the same line. - There should be one blank line before a method.
✅ Correct:
class User {
private string $name;
public function getName(): string {
return $this->name;
}
}
❌ Incorrect (Braces on a new line, no blank line before the method):
class User
{
private string $name;
public function getName(): string
{
return $this->name;
}
}
4. Function and Method Arguments
- No space before the opening parenthesis.
- One space after the comma.
- No trailing comma in the last parameter.
✅ Correct:
function registerUser(string $name, int $age): bool {
return true;
}
❌ Incorrect (Extra spaces):
function registerUser ( string $name , int $age , ): bool {
return true;
}
5. Control Structures (if, for, while, switch)
- Braces are always required.
- Spaces before and after parentheses.
✅ Correct:
if ($age >= 18) {
echo "You are an adult.";
} elseif ($age > 0) {
echo "You are a minor.";
} else {
echo "Invalid age.";
}
❌ Incorrect (Missing braces and spaces):
if($age >= 18) echo "You are an adult.";
elseif($age > 0) echo "You are a minor.";
else echo "Invalid age.";
6. Switch Statements
-
casestatements must be indented. - There must be a break or return in each
case.
✅ Correct:
switch ($status) {
case 'active':
echo "User is active.";
break;
case 'inactive':
echo "User is inactive.";
break;
default:
echo "Unknown status.";
break;
}
❌ Incorrect (Cases not indented, missing break):
switch ($status) {
case 'active':
echo "User is active.";
case 'inactive':
echo "User is inactive.";
default:
echo "Unknown status.";
}
7. Arrays
- Arrays must use the short syntax (
[]instead ofarray()). - Each element in a multiline array should be on a new line.
✅ Correct (Short array syntax, proper formatting):
$users = [
'Alice',
'Bob',
'Charlie',
];
❌ Incorrect (Old syntax, multiple values on one line):
$users = array('Alice', 'Bob', 'Charlie');
8. Visibility in Methods
- Abstract, final, and static must be declared before visibility.
✅ Correct:
class Logger {
public static function log(string $message): void {
echo $message;
}
}
❌ Incorrect (Wrong order of modifiers):
class Logger
{
static public function log(string $message): void
{
echo $message;
}
}
9. Blank Lines and Indentation
- Use 4 spaces for indentation (not tabs).
- One blank line between methods.
- Two blank lines before a class definition.
✅ Correct:
namespace App\Models;
class User {
private string $name;
public function getName(): string {
return $this->name;
}
public function setName(string $name): void {
$this->name = $name;
}
}
❌ Incorrect (No spacing between methods, tabs instead of spaces):
class User
{
private string $name;
public function getName(): string
{
return $this->name;
}
public function setName(string $name): void
{
$this->name = $name;
}
}
Summary of PSR-12
| Rule | Description |
|---|---|
| UTF-8 Encoding | PHP files must use UTF-8 without BOM |
| Namespaces & Use Statements | Must be declared in order and alphabetically sorted |
| Class Declarations | Braces {} must be on the same line as the class definition |
| Properties & Methods | One property per line, methods must use camelCase |
| Function Arguments | No space before (), one space after ,
|
| Control Structures | Always use braces {} for if, else, for, while
|
| Arrays | Must use [] short syntax, multi-line elements on separate lines |
| Blank Lines | One blank line before methods, two before classes |
Top comments (5)
I thought I would learn something new, but it turns out I am writing code according to PSR-12.
When I started learning - I wrote it wrong, but then there was no such standard. In my opinion, getting to know the standards of writing code should be the first thing before learning the language.
This standard is updated long ago as php-fig.org/per/coding-style/
Thanks for the comment, I'll post about this update.
some are incorrect actually. Here is the original php-fig.org/psr/psr-12/
Only this package "squizlabs/php_codesniffer"