//brass.h -- bank account classes
#ifndef BRASS_H_
#define BRASS_H_
#include
//brass account class
class Brass
{
private:
std::string fullName; //x姓名
long acctNum; //账号
double balance; //当前结余
public:
Brass(const std::string & s = "Nullbody", long an = -1, double bal = 0.0); //创建账号
void Deposit(double amt); //存款
virtual void ViewAcct() const; //显示账号情况
virtual void Withdraw(double amt); //取款
double Balance() const; //获取当前余额
virtual ~Brass(){}
};
//brass plus account class
class BrassPlus : public Brass
{
private:
double maxLoan; //透支上限
double rate; //利率
double owesBank; //当前透支总额
public:
BrassPlus(const std::string & s = "Nullbody", long an = -1, double bal = 0.0, double ml = 500, double r = 0.11125);
BrassPlus(const Brass & ba, double ml = 500, double r = 0.11125);
virtual void ViewAcct() const; //显示账号情况
virtual void Withdraw(double amt); //取款
void ResetMax(double m) { maxLoan = m; } //修改透支上限
void ResetRate(double r) { rate = r; } //修改利率
void ResetOwes() { owesBank = 0; } //还款，，欠款置零
};
#endif
上面是c++primer plus 第六版的程序清单13.7
想问问，在基类Brass中设为虚的两个方法 viewacct() 和 withdraw()，在派生类中为什么也设为虚的，我把派生类中的关键字virtual 删掉也没有什么编译和运行的问题……
