#include<iostream.h>
#include"book.h"

class booksale:public book
{
private:
	static float rate;					//設置靜態成員稅率rate
	static float account;				//設置靜態成員銷售總計account
public:	
	int num;							//購買一本書的數量
	void setnum(int);
	int  getnum();
	static float getrate();				//返回靜態稅率rate
	static void setaccount(float);		//使銷售總計account累加
	static float getaccount();			//返回靜態稅率account
};

//		靜態成員變量的賦值
float booksale::rate=0.06f;				
float booksale::account=0.0f;

void booksale::setnum(int n)
{
	num=n;
}

int booksale::getnum()
{
	return num;
}

float booksale::getrate()				//返回靜態稅率rate
{
	return rate;
}
float booksale::getaccount()			//返回靜態稅率account
{
	return account;
}
void booksale::setaccount(float f)		//使銷售總計account累加
{
	account+=f;
}