Revision Exercise - 2

Exercise 1

Given an initialisation of the following structure type, describe what happens with each initialisation. Explain any problems with these initialisations.

struct Date {
    int month;
    int day;
    int year;
};

1. Date date = {12, 21};

2. Date date = {12, 21, 20, 22};

3. Date date = {12, 21, 22};

Exercise 2

Define a structure type to contain information about a given person. The information that this structure should contains are:

• The annual salary for the person

• The accrued vacation for the person (represented as a whole number of days)

• Status, which is either hourly or salaried, represented by two char values 'H' and 'S' respectively.

This structure type is to be called EmployeeRecord

Exercise 3

Part 1

Given the following class declaration:

class DayOfYear {
    int day;
    int month;
public:  
    void input();
    void output();
};

Implement the DayOfYear::input and DayOfYear::output functions such that the following program results in the following output:

int main() {
    DayOfYear dayOfYear;
    dayOfYear.input();
    dayOfYear.output();
}

Enter the day of the month: 13
Enter the month as a number: 5
day=13, month=5

Define the member functions separately from the class, using the scope resolution operator (::).

Part 2

Create a private member function DateOfYear::check_date that will be called by DateOfYear::input to ensure that the dates being input are valid:

• The day of the month cannot be less than 1, and cannot exceed 31.

• The month of the year cannot be less than 1, or greater than 12.

Part 3

Create two constructors for the DayOfYear class. The first should take two int parameters corresponding to the day and month respectively. The second should have no parameters which constructs a date represented as January 1.

Create two DayOfYear variables that use each of these constructors.

Part 4

Suppose we now want to be able to compare two instances of DayOfYears, we can do so by overloading the == operator.

Create this overload function, that returns true if both the day and month member variables of a given DayOfYear is equal to another.

DayOfMonth first = DayOfMonth(3, 6);
DayOfMonth second = DayOfMonth(3, 6);

if (first == second) {
    std::cout << "The dates are equal!" << std::endl;
}

Implement the same for the operator <, which tests if a date comes before another.

Exercise 4

Consider the following class definition:

class Automobile {
private:
    double price;
    double profit;
    double get_profit();
    
public:
    void set_price(double new_price);
    void set_profit(double new_profit);
    double get_price();
};

Suppose the program has created two instances of Automobile and has set the values of all member variables to some value:

Automobile hyundai, jaguar;

Which of the following statements are allowed to be called from main()?

1. hyundai.price = 1999.99

2. jaguar.set_price(30000.10)

3. double a_price = jaguar.get_price();

4. double a_profit = jaguar.get_profit();

5. double b_profit = hyundai.get_profit();

Exercise 5

Consider the following class definition:

class Foo {
public:
    Foo(int x, char y);
    Foo(); 
    void bar();
private:
    int x;
    char y;
};

Assuming that all the functions declared have been later defined, which of the following are legal?

1. Foo foo_one(42, 'A')

2. Foo foo_two;

3. Foo foo_three();

4. foo_one = Foo(99, 'B');

5. foo_one = Foo();

6. foo_one = Foo;

Exercise 6

1. Define a simple class Foo that inherits from a class Bar. (Use public inheritance)

2. If Bar were to have any private member variables or functions, would these be accessible in Foo? If not, how can we change it so that it can be accessible within Foo?

Exercise 7

Given the following class definitions:

class Fish {
public:
    void greet() {
        std::cout << "I am a Fish" << std::endl;
    }
};

class Tuna {
public:
    void greet() {
        std::cout << "I am a Tuna!" << std::endl;
    }
};

Predict the output of the following program:

int main() {
    Fish fish;
    Tuna tuna;
    
    fish.greet();
    tuna.greet();
    
    tuna.Fish::greet();
    fish.Fish::greet();
}

What would be the output if we removed the Tuna::greet function?