C++ 继承中的访问控制

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我是靠谱客的博主秀丽美女，这篇文章主要介绍C++ 继承中的访问控制，现在分享给大家，希望可以做个参考。

继承类型	基类成员访问说明符	派生类成员访问说明符
public	public	public
	protected	private
	private	inaccessiable
protected	public	protected
	protected	protected
	private	inaccessiable
private	public	private
	protected	private
	private	inaccessible

子类中的友元函数只能通过子类对象去访问基类的protected成员

class Base {
protected: 
	int prot_mem = 10;
};
class Child : public Base {
public:
	int getMember() { return prot_mem; }
	friend int getMember1( Child child);
	friend int getMember2(Base base);
};

int getMember1(Child child)
{
	return child.prot_mem; //correct, can access
}
int getMember2(Base base)
{
	return base.prot_mem;// error C2248: 'Base::prot_mem': cannot access protected member declared in class 'Base' 
}