friend_class.cpp

友元类的一种设计

#include <stdio.h>
#include <string.h>

#define SZ 20

struct holder{
	private:
		int a[SZ];
	public:
		void initialize();
		
		struct pointer{
			private:
				holder* h;
				int * p;
			public:
				void initialize(holder* H);
				void next();
				void previous();
				void top();
				void end();
				int read();
				void set(int i);
		};
		friend holder::pointer;
};

void holder::initialize()
{
	memset(a, 0, sizeof(int) * SZ);
}

void holder::pointer::initialize(holder* H)
{
	h = H;
	p = h->a;
}

void holder::pointer::next()
{
	if( p < &(h->a[SZ-1]) )
		p++;
}
void holder::pointer::previous()
{
	if( p > &(h->a[0]) )
		p--;
}
void holder::pointer::top()
{
	p = &(h->a[0]);
}
void holder::pointer::end()
{
	p = &(h->a[SZ-1]);
}

void holder::pointer::set(int i)
{
	*p = i;
}

int main()
{
	return 0;
}