Classes and inheritance

[DeathLeap]

So I wrote a simple code about classes. I have two questions:

1) can I avoid giving definition of the default constructor?
2) can I put the default constructor under "private" section?

#include <iostream>
#include <string>

using namespace std;

class Student{

private:
	string Name;
	string Address;
	string ID;
	string SSN;
public:
	void registerClass();
};

class fullTimeStudent : public Student{

private:
	float GPA;
public:
	void takeExam();
};

class partTimeStudent : public Student{

private:
	int numberOfCourses;
public:
	void attendClass();
};

void Student::registerClass(){

	cout << "I am in registerClass()" << endl;

}

void fullTimeStudent::takeExam(){

	cout << "I am in takeExam()" << endl;

}

void partTimeStudent::attendClass(){

	cout << "I am in attendClass()" << endl;

}

int main(){

	Student student1;
	student1.registerClass(); 

	fullTimeStudent fullTimeStudent1;
	fullTimeStudent1.takeExam();

	partTimeStudent partTimeStudent1;
	partTimeStudent1.attendClass();


	system("Pause");
	return 0;
}

void registerClass();

[MiiNiPaa]

1) can I avoid giving definition of the default constructor?

Elaborate what fo you want. If you do not define any constructor, default constructor will be generated for you.
In C++11 you can explicitely state that you want compiler-generated constructor by using:

class foo
{
public:
    foo() = default;

2) can I put the default constructor under "private" section?

Yes, but there is little reason to do so.
If you do not want to have default constructor removed and uncallable, use
foo() = delete;

[DeathLeap]

How can I demonstrate that it's ok not to define the default constructor with the code I provided?

[MiiNiPaa]

In your case default constructor is generated by compiler and you are using it.
To explicitely state that you are fine with compiler generated version, you can use

class Student
{
public:
    Student() = default;

[DeathLeap]

But although I didn't state that in my code, the compiler will still generate a default constructor?

[MiiNiPaa]

Yes it will because default constructor is one of the special member functions and you are using it in your code. I fact you do stated that you want default constructor to be generated on line 53 where it was used first time.

[DeathLeap]

Can you copy my code and note where does the constructor, objects reside in it?

[MiiNiPaa]

int main()
{
	Student student1; //Calls default constructor for Student
	student1.registerClass(); 

	fullTimeStudent fullTimeStudent1; //Calls default constructor for fullTimeStudent 
                                          //Which in order calls Student default constructor
	fullTimeStudent1.takeExam();

	partTimeStudent partTimeStudent1; //Calls default constructor for partTimeStudent 
                                          //Which in order calls Student default constructor
	partTimeStudent1.attendClass();


	system("Pause");
	return 0;
}

[DeathLeap]

So I can't avoid not defining the default constructor in this case, because my code will just not work.

int main(){

	
	Student.registerClass(); 

	fullTimeStudent.takeExam();

	partTimeStudent.attendClass();


	system("Pause");
	return 0;
}

[MiiNiPaa]

So I can't avoid not defining the default constructor in this case, because my code will just not work.

Yes, you cannot. Why would you want that anyway?

Student.registerClass(); You cannot do that. Non-static member functions should be invoked on instances of class, not on the classes themself