需要帮助理解C++类的语法

我已经完成了哈佛CS50课程，并且使用python相当多。我现在正在做一个C++课程(Microsoft的)，学习练习让我创建了几个课程。该练习专门要求我在 main 中实例化一些对象并返回一些值;

#include <iostream>
#include "School.h"
int main()
{
Student student1("Joe", "Bloggs", 31, "123 Fake Street", "London");
Student student2("Fred", "Adams", 24, "95 Something Avenue", "Manchester");
Student student3("John", "Doe", 90, "44a Old Man Lane", "Kettering");
Course course1("Introduction to Psychology");
course1.addStudent(student1);
course1.addStudent(student2);
course1.addStudent(student3);
Teacher teacher1("Helen", "Professorson", 48, "15 Teacher Way", "Kent");
course1.addTeacher(teacher1);
std::cout << course1.getCourseName() << std::endl;
teacher1.GradeStudent();
}

我正在使用头文件和 cpp 文件来定义类，School.h：

#pragma once
#include <string>
class Person
{
public:
// Constructors and Destructors
Person();
Person(std::string, std::string);   // First and Last Name
Person(std::string, std::string, int, std::string, std::string, std::string); // fName, lName, Age, Address, City, Phone
~Person();
// Member functions
std::string getFirstName();
void setFirstName(std::string);
std::string getLastName();
void setLastName(std::string);
int getAge();
void setAge(int);
std::string getAddress();
void setAddress(std::string);
std::string getCity();
void setCity(std::string);
std::string getPhone();
void setPhone(std::string);
private:
std::string _fName;
std::string _lName;
int _age;
std::string _address;
std::string _city;
std::string _phone;
};
class Student : public Person
{
public:
// Constructors and Destructors

// Member Functions
void SitInClass();
};
class Teacher : public Person
{
public:
// Member Functions
void SitInClass();
void GradeStudent();
};
class Course
{
public:
// Constructors and Desctructors
Course();
Course(std::string); // course name
~Course();
// Member functions
void addStudent(Student);
void addTeacher(Teacher);
// Getters and Setters
std::string getCourseName();
void setCourseName(std::string);

private:
// Member variables
std::string _courseName;
Student _students[30];
Teacher _teacher;
};

学校.cpp：

#include "School.h"
#include <iostream>
#include <string>
// Constructors
Person::Person()
{
std::string _fName{};
std::string _lName{};
int _age{};
std::string _address{};
std::string _city{};
std::string _phone{};
}
Person::Person(std::string fName, std::string lName)
{
std::string _fName{ fName };
std::string _lName{ lName };
int _age{};
std::string _address{};
std::string _city{};
std::string _phone{};
}
Person::Person(std::string fName, std::string lName, int age, std::string address, std::string city, std::string phone)
{
std::string _fName{ fName };
std::string _lName{ lName };
int _age{ age };
std::string _address{ address };
std::string _city{ city };
std::string _phone{ phone };
}
// Destructor
Person::~Person()
{
}
std::string Person::getFirstName()
{
return this->_fName;
}
void Person::setFirstName(std::string fName)
{
this->_fName = fName;
}
std::string Person::getLastName()
{
return this->_lName;
}
void Person::setLastName(std::string lName)
{
this->_lName = lName;
}
int Person::getAge()
{
return this->_age;
}
void Person::setAge(int age)
{
this->_age = age;
}
std::string Person::getAddress()
{
return this->_address;
}
void Person::setAddress(std::string address)
{
this->_address = address;
}
std::string Person::getCity()
{
return this->_city;
}
void Person::setCity(std::string city)
{
this->_city = city;
}
std::string Person::getPhone()
{
return this->_phone;
}
void Person::setPhone(std::string phone)
{
this->_phone = phone;
}
void Student::SitInClass()
{
std::cout << "Sitting in main theater" << std::endl;
}
void Teacher::SitInClass()
{
std::cout << "Sitting at front of class" << std::endl;
}
void Teacher::GradeStudent()
{
std::cout << "Student Graded" << std::endl;
}
Course::Course()
{
Student* _students;
Teacher* _teacher;
std::string _name{};
}
Course::Course(std::string name)
{
Student* _students[30];
Teacher* _teacher;
std::string _name{ name };
}
Course::~Course()
{
}
void Course::addStudent(Student student)
{
// TODO: Loop through _students and insert new student in
}
void Course::addTeacher(Teacher teacher)
{
this->_teacher = &teacher;
}
std::string Course::getCourseName()
{
return this->_name;
}
void Course::setCourseName(std::string name)
{
this->_name = name;
}

我实际上还没有被教导继承，但由于学生和老师都需要相同的变量(姓名、年龄、地址等)。我决定这样做是明智的。

不过有一些问题：

1. 我在main.cpp中对Student和Teacher的实例不正确。我认为是因为他们继承自 Person(？如何在这些派生类中创建构造函数？我用谷歌搜索了这个，但解决方案似乎不起作用。

2. Course班需要一系列学生。我是否必须在头文件中指定数组的大小？我在头文件和 cpp 文件中都指定了 30 似乎很愚蠢，但如果我不这样做，VSstudio 会抱怨。

3. 我在这里使用字符串。我以前从另一门课程中学到了关于 char* 和关于字符串的内存。为所有这些字符串类变量分配了多少个字符？如果我实例化一个名字为"Joe"的学生，然后想稍后使用student1.SetFirstName将他的名字更改为"Joseph"，这会导致分段错误吗？