# Pointer Errors and Inheritance

#### Part A

• Locate the errors in the following code. You will notice, not every line will contain a mistake. Pay close attention to the line preceding it. Look out for uninitialized pointers, NULL pointers, pointers to deleted objects, and confusing pointers with objects.

1 int* p = new int;

2 p = 5;

3 *p = *p + 5;

4 Employee e1 = new Employee(“Hacker, Harry”, 34000);

5 Employee e2;

6 e2->set_salary(38000);

7 delete e2;

8 Time* pnow = new time ();

9 Time* t1 = new Time(2, 0, 0);

10 cout << t1->seconds_from(pnow);

11 delete*t1;

12 cout << t1->get_seconds();

13 Employee* e3 = new Employee(“Lin, Lisa”, 68000);

14 cout << e3.get_salary();

15 Time* t2 = new Time(1, 25, 0);

16 cout << *t2.get_minutes();

17 delete t2;

#### Part B

• Implement a class person with the following fields:

The nam

A pointer to the persons best friend

A popularity counter that indicates how many people have this person as their best friend

• Write a program that reads in a list of names, allocates a new Peron for every one of them, and places them in a vector<Person*>. Next, request the name of each best friend for every Person objects. Find the object matching the friend’s name, and call a set_best_friend member function to update the pointer and counter. Lastly, print out every Person objects. Labeling the name, best friend, and popularity counter for all.

#### Part C

• Consider the following classes B and D:

Class B

{

Public;

B();

B( int n);

};

B::B()

{

cout << “B::B()n”;

}

B::B(int n)

{

cout << “B::B(“ << n << “)n”;

}

Class D : Public B

{

public:

D();

D( int n);

private:

B b;

};

D::D()

{

cout << “D::D()n”;

}

D::D(int n) : B(n)

{

b = B(-n);

cout << “D::D(“<< n <<”)n”;

}

What does the following program print?

int main()

{

D d(3);

return 0;

}

• Determine the answer by hand, not by compiling and running the program.

#### Part D

• Implement a base class person. Derive classes Student and Professor from Person. Every Person has will have a name, and birthdate. Every student will have a major, and every professor will have an income. Write the class definitions, the constructors, and the member functions print() for all classes.