Question: Explain the concept of dependency injection.

Answer: Dependency injection is a design pattern where the dependencies of a class are injected from the outside rather than created within the class. It promotes loose coupling and testability.

Example:

class Database { 
/* database operations */ 
}

 class UserRepository { 
private $database; 
public function __construct(Database $database) { 
$this->database = $database; 
}
 }