EX 8

人生的许多大困难，只要活着，没什么是解决不了的，时间和智慧而已

　　　　　　　　　　　　　　　　　　　　　　　　——三毛

ps:以后不能说自闭了，之前说了一次，然后一语成谶，以后要说rank1。

手慢无场

Problem A: Person类与Student类的关系

main函数：

int main()
{
    string n;
    int a, g;
    cin>>n>>a>>g;
    Student student(n, a, g);
    student.Person::show();
    student.show();
    return 0;
}

没什么考点吧应该，怎么说怎么写，本来以为是考虚函数的，结果发现想多了。。。。

AC代码：

#include <bits/stdc++.h>
using namespace std;
 
class Person
{
    string name;
    int age;
public:
    Person(string _name,int _age):name(_name),age(_age){cout << "A person " << name << " whose age is " << age << " is created." << endl;}
    ~Person()
    {
        cout << "A person " << name << " whose age is " << age << " is erased." << endl;
    }
    void show()
    {
        cout << "Name is " << name << " and age is " << age << "." << endl;
    }
};
class Student :public Person
{
        int grade;
    public:
        Student(string _name,int _age,int _grade):Person(_name,_age),grade(_grade){cout << "A student whose grade is " << grade << " is created." << endl;}
        ~Student()
        {
            cout << "A student whose grade is " << grade << " is erased." << endl;
        }
        void show()
        {
            cout << "Grade is " << grade << "." << endl;
        }
};

Problem B: 家教课程

main函数：

int main()
{
    string s1, s2, s3, s4;
    int i;
    cin>>s1>>s2>>s3>>s4>>i;
    Person person1(s1), person2(s2);
    Teacher teacher(s1, s3);
    Student student(s2, i);
    Course course(s1, s2, s3, s4, i);
    return 0;
}

细节题，我看到了hint，但是我居然认为它在框我，想想我脑回路也是清奇。

类的继承加上类的组合吧，但不算难。

AC代码：

#include <bits/stdc++.h>
using namespace std;
class Person
{
    friend class Student;
    friend class Teacher;
   string name;
   public:
       Person(string _name):name(_name){
       cout << "Person " << name << " is created." << endl;
       }
       ~Person()
       {
           cout << "Person " << name << " is erased." << endl;
       }
};
class Student :public Person
{
      int id;
  public:
    Student(string _name,int _id):Person(_name),id(_id){
        cout << "Student " << name << " with id " << id << " is created." << endl;
    }
    ~Student()
    {
        cout << "Student " << name << " with id " << id << " is erased." << endl;
    }
};
class Teacher:public Person
{
    string work;
public:
    Teacher(string _name,string _work):Person(_name),work(_work){
        cout << "Teacher " << name << " with position " << work << " is created." << endl;
    }
    ~Teacher()
    {
        cout << "Teacher " << name << " with position " << work << " is erased." << endl;
    }
};
class Course
{
    Teacher t;
    Student s;
    string OPP;
public:
    Course(string _name1,string _name2,string _work,string _OPP,int _id):t(_name2,_work),s(_name2,_id),OPP(_OPP){
    cout << "Course " << OPP << " is created." << endl;
    }
    ~Course()
    {
        cout << "Course " << OPP << " is erased." << endl;
    }
};

Problem C: 一帮学生

main函数：

int main()
{
    int year, month, day, id, i;
    string name;
    int num;
    cin>>num;
    Student **students = new Student*[num];
    for (i = 0; i < num; i++)
    {
        cin>>year>>month>>day>>id>>name;
        students[i] = new Student(year, month, day, name, id);
    }
    for (i = 0;i <num; i++)
        delete students[i];
    delete[] students;
    return 0;
}

考点：静态数据成员+继承

AC代码：

#include <bits/stdc++.h>
using namespace std;
class Date
{
    friend class Person;
    friend class Student;
    int yy,mm,dd;
public:
    Date(int _y,int _m,int _d):yy(_y),mm(_m),dd(_d){
        cout << "Date " << yy << "-" << mm << "-" << dd << " is created." << endl;
    }
    ~Date()
    {
        cout << "Date " << yy << "-" << mm << "-" << dd << " is erased." << endl;
    }
};
class Person
{
    friend class Student;
    Date birth;
    string name;
    static int numOfPersons;
public:
    Person(int _y,int _m,int _d,string _name):birth(_y,_m,_d),name(_name){numOfPersons++;
       cout << "The " << numOfPersons << "th person " << name << " whose birthday is " << birth.yy << "-" << birth.mm << "-" << birth.dd << " is created." << endl;
    }
    ~Person()
    {
        numOfPersons--;
        cout << "Person " << name << " whose birthday is " << birth.yy << "-" << birth.mm << "-" << birth.dd <<" is erased." << endl;
    }
 
};
class Student :public Person
{
        int id;
        static int numOfStudents;
    public:
        Student(int _y,int _m,int _d,string _name,int _id):Person(_y,_m,_d,_name),id(_id){numOfStudents++;
        cout << "The " << numOfStudents << "th student " << name <<  " whose birthday is " << birth.yy << "-" << birth.mm << "-" << birth.dd << " and id is " << id << " is created." << endl;
        }
        ~Student()
        {
            cout << "Student " << name << " whose birthday is " << birth.yy << "-" << birth.mm <<"-"<< birth.dd <<" and id is " << id << " is erased." << endl;
 
            numOfStudents--;
        }
};
int Person::numOfPersons = 0;
int Student::numOfStudents = 0;