How can PHP developers ensure proper variable and function visibility within classes for efficient code execution?

To ensure proper variable and function visibility within classes in PHP, developers can use access modifiers like public, private, and protected. By using these modifiers, developers can control the visibility of properties and methods within a class, ensuring that they are only accessed or modified in the intended way. This helps in maintaining code integrity and prevents unintended modifications or access to class members.

class MyClass {
    public $publicVar;
    private $privateVar;
    protected $protectedVar;

    public function publicMethod() {
        // code here
    }

    private function privateMethod() {
        // code here
    }

    protected function protectedMethod() {
        // code here
    }
}