What should be paid attention to when reviewing code to ensure its quality?

When conducting a code review in PHP, the following aspects should be paid attention to:

• Readability and coding style: adherence to PSR standards (e.g., PSR-12), clear variable and function names.
• Security: checking for vulnerabilities, such as protection against SQL injections, XSS, proper use of filtering and validation of data.
• Logic and architecture: the code should be logical, without duplication, with proper separation of responsibilities.
• Error handling: correct use of exceptions and checks to avoid failures.
• Performance: avoid unnecessary database queries, heavy operations in loops.
• Testability: the code should be covered by tests or be easily testable.

Example of style check:

// Bad
function getuser(){return $this->user;}

// Good
public function getUser(): User
{
    return $this->user;
}