Question

C++面向对象程序设计考题求助详细解答

某公司有两种雇员：正式雇员，他们每周无论工作时间长短，付给固定的薪水；合同工，按小时付薪水；定义三个类：Employee，SalariedEmployee和HourlyEmployee。Employee是抽象类，存储雇员的姓名（name：string类型）和id（id：string类型）；SalariedEmploy需要加上正式雇员的薪水（salary：double类型）；HourlyEmploy需要加上合同工的每小时工资（wage：double类型）和每周工作的小时数（hours：double类型）；三个类都有printf（）函数输出雇员的所有信息，还有一个earings（）函数返回雇员的收入。要求：（1）按以上要求写出三个类的实现并简单验证。

（2）实现多态，提示：创建一个指向Employee的指针数组或引用。然后用new创建若干个SalariedEmployee或HourlyEmployee类型的对象来保存数据，最后将指向对象的指针存入数组。

（3）将数组中的指针所指向的所有雇员的信息写入一个磁盘文件：employee，然后再从该文件中读出并输出到屏幕。

Answer 1

#include <iostream>
#include <cstdio>
using namespace std;
class Employee
{
public:
Employee(){}
virtual ~Employee(){}
public:
virtual void print(){}
virtual double earing(){}
public:
string name;
string id;
};

class SalariedEmploy :public Employee
{
public:
SalariedEmploy(string name,string id,double salary)
{
this->name = name;
this->id = id;
this->salary = salary;
}
virtual ~SalariedEmploy(){}
public:
void print()
{
cout << "name: " <<name<< " id: " <<id<< " salary: " <<salary<<endl;
}
double earing()
{
return salary;
}
private:
double salary;
};

class HourlyEmploy :public Employee
{
public:
HourlyEmploy(string name,string id,double wage,double hours)
{
this->name = name;
this->id = id;
this->wage = wage;
this->hours = hours;
}
virtual ~HourlyEmploy(){}
public:
void print()
{
cout << "name: " <<name<< " id: " <<id<< " salary: " <<wage*hours<<endl;
}
double earing()
{
return wage*hours;
}
private:
double wage;
double hours;
};

int main()
{
Employee* p[5];
p[0] = new SalariedEmploy("MissA","sd0001",7000);
p[1] = new SalariedEmploy("Apink","sd0002",8000);
p[2] = new SalariedEmploy("Tara","sd0003",9000);
p[3] = new HourlyEmploy("Fx","sd0004",105,60);
p[4] = new HourlyEmploy("Kara","sd0005",100,62);
FILE* fp = fopen("employee","a+");
for(int i=0; i<5; i++)
{
char buf[200];
const char* Name = p[i]->name.c_str();
const char* Id = p[i]->id.c_str();
sprintf(buf,"name:%s id:%s salary:%lf",Name,Id,p[i]->earing());
fwrite(buf,1,sizeof(buf),fp);
}
fseek(fp,0,SEEK_SET);//文件指针指向文件头
for(int j=0; j<5; j++)
{
char vt[200];
fread(vt,1,sizeof(vt),fp);
printf("%s\n",vt);
}
fclose(fp);
}
程序我自己经过编译没有问题
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