Classes and Objects in C++

class Led {
public:
    explicit Led(int pin) : pin_(pin) { pinMode(pin_, OUTPUT); }
    void on()  { digitalWrite(pin_, HIGH); }
    void off() { digitalWrite(pin_, LOW); }
private:
    int pin_;
};

Led status(13);
status.on();

public members form the interface; private members are hidden implementation (encapsulation). A struct is the same as a class except members are public by default.