编译器：vs2022

main.cpp

#include <iostream>
#include <iomanip>
#include "person.h"

const int Sum = 2;

class Group
{
protected:
    PostGra st[Sum];
    int sum;
public:
    Group();
    void Input();
    void SortByID();
    void Output();
};

Group::Group()
{
    sum = Sum;
}

void Group::Input()
{
    int i;
    for (i = 0; i < sum; i++)
        st[i].Input();
}

void Group::SortByID()
{
    int index, i, k;
    PostGra temp;
    for (k = 0; k < sum - 1; k++)
    {
        index = k;
        for (i = k + 1; i < sum; i++)
            if (st[i].GetID() < st[index].GetID())
                index = i;
        if (index != k)
        {
            temp = st[index];
            st[index] = st[k];
            st[k] = temp;
        }
    }
}

void Group::Output()
{
    int i;
    std::cout << std::endl << "The group information:" << std::endl;
    std::cout << "ID" << std::setw(10) << "Name" << std::setw(10) << "Age" << std::setw(10) << "Gender" <<
        std::setw(10) << "Spec" << std::setw(10) << "research"<< std::endl;
    for (i = 0; i < sum; i++)
    {
        std::cout << st[i].GetID() << std::setw(10) << st[i].GetName()
            << std::setw(10) << st[i].GetGender() << std::setw(10) << st[i].GetSpeciality()
            << std::setw(10) << st[i].GetResearchTopic() << std::setw(10) << st[i].GetAcademicTitle() << std::endl;
    }
}

int main()
{
    Group group;
    group.Input();
    group.SortByID();
    group.Output();
    return 0;
}

person.h

#pragma once
#ifndef _PERSON
#define _PERSON
#include <string>

class Person
{
protected:
    std::string ID;
    std::string name;
    std::string gender;
public:
    Person(std::string = "000", std::string = "unknown", std::string = "unknown");
    void Input();
    std::string GetID();
    std::string GetName();
    std::string GetGender();
};

class Student : virtual public Person
{
protected:
    std::string speciality;
public:
    Student(std::string, std::string, std::string = "000", std::string = "unknown");
    void Input();
    std::string GetSpeciality();
};

class Graduate :virtual public Student
{
protected:
    std::string researchTopic;
public:
    Graduate(std::string=" ", std::string=" ", std::string=" ", std::string = "000", std::string = "unknown");
    void Input();
    std::string GetResearchTopic();
};

class Teacher :virtual public Person
{
protected:
    std::string academicTitle;
public:
    Teacher(std::string, std::string, std::string, std::string = "unknown");
    void Input();
    std::string GetAcademicTitle();
};

class PostGra :public Graduate, public Teacher
{
public:
    PostGra(std::string=" ", std::string=" ", std::string=" ", std::string=" ", std::string = "000", std::string = "unknown");
    void Input();
};
#endif

person.cpp

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

Person::Person(std::string id, std::string name, std::string gender)
{
    ID = id;
    name = name;
    gender = gender;
}

void Person::Input()
{
    std::cout << "Enter ID: ";
    std::cin >> ID;
    std::cout << "Enter name: ";
    std::cin >> name;
    std::cout << "Enter gender: ";
    std::cin >> gender;
}

std::string Person::GetID()
{
    return ID;
}

std::string Person::GetName()
{
    return name;
}

std::string Person::GetGender()
{
    return gender;
}

Student::Student(std::string id, std::string name, std::string gender, std::string speciality) : Person(id, name, gender)
{
    speciality = speciality;
}

void Student::Input()
{
    Person::Input();
    std::cout << "Enter speciality: ";
    std::cin >> speciality;
}

std::string Student::GetSpeciality()
{
    return speciality;
}

Graduate::Graduate(std::string id, std::string name, std::string gender, std::string speciality, std::string rese) :Person(id, name, gender), Student(id, name, gender, speciality)
{
    researchTopic = rese;
}

void Graduate::Input()
{
    Student::Input();
    std::cout << "Enter research topic: ";
    std::cin >> researchTopic;
}

std::string Graduate::GetResearchTopic()
{
    return researchTopic;
}

Teacher::Teacher(std::string id, std::string name, std::string gender, std::string title) : Person(id, name, gender)
{
    academicTitle = title;
}

void Teacher::Input()
{
    Person::Input();
    std::cout << "Enter academic title: ";
    std::cin >> academicTitle;
}

std::string Teacher::GetAcademicTitle()
{
    return academicTitle;
}

PostGra::PostGra(std::string id, std::string name, std::string gender, std::string speciality, std::string rese, std::string title) : Person(id, name, gender), Student(id, name, gender, speciality), Teacher(id, name, gender, title)
{
    ;
}

void PostGra::Input()
{
    Graduate::Input();
    std::cout << "Enter academic title: ";
    std::cin >> academicTitle;
}