C++ 訪问控制权限图解

基类訪问权限	类继承方式	子类訪问权限
public		public
protected	public	protected
private		No Access
public		protected
protected	protected	protected
private		No Access
public		private
protected	private	private
private		No Access
基类訪问权限	类继承方式	子类訪问	子类对象訪问
public		ok	ok
protected	public	ok	no
private		no	no
public		ok	ok
protected	protected	ok	no
private		no	no
public		ok	no
protected	private	ok	no
private		no	no