//时间：2016.4.8
#include <iostream>
#include<stdlib.h>
using namespace std;
class SavingAccount//定义一个名为SavingAccount的类
{
private:
    double savingsBalance;//私有数据成员，用户的存款
public:
    SavingAccount(double a);//声明构造函数原型
    double calculateMothlyInterest();//声明非静态公有成员函数calculateMothlyInterest
    static void ModifyInterestRate(double);//声明静态成员函数ModifyInterestRate
    static double annualInterestRate;//定义静态数据成员annualInterestRate
    double printsavingsbalance();//声明非静态公有成员函数printsavingsbalance

};

double SavingAccount::annualInterestRate = 0.03;//静态数据成员初始化

SavingAccount::SavingAccount(double a)//定义构造函数SavingAccount，作用是存储用户输入的本金
{
    this->savingsBalance = a;
}

void SavingAccount::ModifyInterestRate(double b)//定义静态成员函数ModifyInterestRate，作用是存储利率
{
    annualInterestRate = b;
}

double SavingAccount::calculateMothlyInterest()//定义非静态成员函数calculateMothlyInterest，作用是计算利息及统计新的余额
{
    double interest = this->savingsBalance * this->annualInterestRate / 12;//计算利息并把值赋给interest
    this->savingsBalance = this->savingsBalance+interest;//这里不是赋值了吗？？！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！
    return interest;//返回interset的值
}
double SavingAccount::printsavingsbalance()//定义非静态成员函数printsavingsbalance，作用是返回savingsbalance的值
{
   
        return this->savingsBalance;
   
}
int main()
{
   
    SavingAccount person1(20000);//建立第一个SavingAccount对象person1
    SavingAccount person2(30000);//建立第二个SavingAccount对象person2
    SavingAccount::ModifyInterestRate(0.03);//调用静态成员函数ModifyInterestRate，给静态数据成员annualInterestRate赋初值
    cout << "person1这个月的利息为:" << person1.calculateMothlyInterest() << "余额:" << person1.printsavingsbalance() << endl;
    cout << "person2这个月的利息为:" << person2.calculateMothlyInterest() << "余额:" << person2.printsavingsbalance() << endl;
    SavingAccount::ModifyInterestRate(0.04);//调用静态成员函数ModifyInterestRate，给静态数据成员annualInterestRate赋初值
    cout << endl;
    cout << "person1下个月的利息为:" << person1.calculateMothlyInterest() << "余额:" << person1.printsavingsbalance() << endl;
    cout << "person2下个月的利息为:" << person2.calculateMothlyInterest() << "余额:" << person2.printsavingsbalance() << endl;
    system("pause");
    return 0;
}

C++不懂。

呜呜 不会怎么解决啊

int main()
{
    
    SavingAccount person1(20000);//建立第一个SavingAccount对象person1
    SavingAccount person2(30000);//建立第二个SavingAccount对象person2
    SavingAccount::ModifyInterestRate(0.03);//调用静态成员函数ModifyInterestRate，给静态数据成员annualInterestRate赋初值
    cout << "余额:" << person1.printsavingsbalance() << "person1这个月的利息为:" << person1.calculateMothlyInterest() << endl;  //其他的代码太多没改我就不贴了，主要是这四个输出语句，先输出了后面的
    cout << "余额:" << person2.printsavingsbalance() << "person2这个月的利息为:" << person2.calculateMothlyInterest() << endl;
    SavingAccount::ModifyInterestRate(0.04);//调用静态成员函数ModifyInterestRate，给静态数据成员annualInterestRate赋初值
    cout << endl;
    cout << "余额:" << person1.printsavingsbalance() << "person1下个月的利息为:" << person1.calculateMothlyInterest() << endl;
    cout << "余额:" << person2.printsavingsbalance() << "person2下个月的利息为:" << person2.calculateMothlyInterest() << endl;
    system("pause");
    return 0;
}

另外C++的帖最好到C++版块问，那里懂的人比较多

非常感谢，谢谢耐心的回复了