Airline Traveler

In this workshop, you are to initialize the data within an object of class type upon its creation.

LEARNING OUTCOMES

Upon successful completion of this workshop, you will have demonstrated the abilities to:

• define a constructor that initializes an object's data at creation time;
• define a default constructor that sets an object to a safe empty state;
• describe what you have learned in completing this workshop.

IN-LAB

Design and code a Traveler module for an airline application.

In the Traveler.h header file, predefine the following constants as integers:

• max_destination_size with the value 32. This represents the maximum number of characters for the destination of the traveler
• max_name_size with the value 16. This represents the maximum num-ber of characters for the name of the traveler

Define a class named Traveler in the sict namespace. The class defines the structure of a traveler's information for an airline company. The class holds the following private information:

• The traveler's first name: an array of characters of size max_name_size (including '\0');
• The traveler's last name: an array of characters of size max_name_size (including '\0');
• The destination: an array of characters of size max_destination_size (including '\0');

Your Traveler type includes the following member functions (which you need to implement make sure to reuse existing code wherever possible instead of duplicating existing code):

default constructor (a no-argument constructor): this constructor sets the Traveler object to a safe empty state;

constructor with 3 parameters: This constructors set the attributes to the data from the parameters, if the parameters are valid.

The first parameter receives the address of a null-terminated C-style string containing the first name of the traveler.

The third parameter receives the address of a null-terminated C-style string containing the name of their destination.

This constructor copies the data at the received addresses to the ob-ject instance variables, only if that data is valid. Data is valid if the address refers to a non-empty string; that is, data is not valid if its address is the null address or the string at that address is empty. If the data is not valid, this constructor sets the object to a safe emp-ty state.

bool isEmpty() const: a query that reports if the Traveler object is in a safe empty state.

void display() const: a query that displays the contents of the Traveler object in the following format (see also the output listing below).

FIRST-NAME LAST-NAME goes to DESTINATION< ENDL>

If the object is in a safe empty state, this function outputs the following message

--> Not a valid traveler! <--< ENDL>

Using the w4_in_lab.cpp implementation file of the main module shown below, test your code and make sure that it works. The expected output from your pro-gram is listed below this source code. The output of your program should match exactly this expected output.

IN-LAB MAIN MODULE

#include < iostream>
#include "Traveler.h"
#include "Traveler.h" // this is intentional

using namespace std;
using namespace sict;

int main() {
Traveler travelers[] = {
Traveler(nullptr, nullptr, "Toronto"),
Traveler(nullptr, "", "Toronto"),
Traveler(nullptr, "Smith", "Toronto"),

Traveler("", nullptr, "Toronto"),
Traveler("", "", "Toronto"),
Traveler("", "Smith", "Toronto"),

Traveler("John", nullptr, "Toronto"),
Traveler("John", "", "Toronto"),
Traveler("John", "Smith", "Toronto"), // valid

Traveler("John", "Smith", nullptr),
Traveler("John", "Smith", ""),
Traveler(nullptr, nullptr, nullptr),
Traveler("", "", ""),
Traveler()
};
cout << "----------------------------------------" << endl;
cout << "Testing the validation logic" << endl;
cout << "(only traveler 9 should be valid)" << endl;
cout << "----------------------------------------" << endl;
for (int i = 0; i < 14; ++i)
{
cout << "Traveler " << i + 1 << ": "
<< (travelers[i].isEmpty() ? "not valid" : "valid") << endl;
}
cout << "----------------------------------------" << endl << endl;

sict::Traveler vanessa("Vanessa", "Williams", "Paris"),
mike("Mike", "Jones", "Tokyo"),
alice("Alice", "Miller", "Rome");

cout << "----------------------------------------" << endl;
cout << "Testing the display function" << endl;
cout << "----------------------------------------" << endl;
vanessa.display();
mike.display();
alice.display();
travelers[0].display(); // not valid
travelers[8].display();
travelers[13].display(); // not valid
cout << "----------------------------------------" << endl << endl;

return 0;
}

IN-LAB EXPECTED OUTPUT

----------------------------------------
Testing the validation logic
(only traveler 9 should be valid)
----------------------------------------
Traveler 1: not valid
Traveler 2: not valid
Traveler 3: not valid
Traveler 4: not valid
Traveler 5: not valid
Traveler 6: not valid
Traveler 7: not valid
Traveler 8: not valid
Traveler 9: valid
Traveler 10: not valid
Traveler 11: not valid
Traveler 12: not valid
Traveler 13: not valid
Traveler 14: not valid
----------------------------------------

----------------------------------------
Testing the display function
----------------------------------------
Vanessa Williams goes to Paris
Mike Jones goes to Tokyo
Alice Miller goes to Rome
--> Not a valid traveler! <--
John Smith goes to Toronto
--> Not a valid traveler! <--
----------------------------------------

AT-HOME

In the "at home" part of this workshop, you enhance your Traveler class by adding date information.

Copy your Traveler module from your in-lab solution. Add data members that store the following additional information to your Traveler class:

year of departure: an integer
month of departure: an integer
day of departure: an integer

To manage this data, declare in your Traveler class definition, the following new member functions and implement them in the .cpp file of your Traveler module:

constructor with 6 parameters: this constructor receives the addresses of the null-terminated C-style strings containing the traveler's first name, last name and destination along with the year, month and day of departure.

Like the other constructors, this constructor validates the parameters before accepting them. This constructor stores the data in the ob-ject's instance variables only if all of the data received is valid. If any data is invalid, this constructor sets the object to a safe empty state.

• Each string is valid if its address is not null and it is not empty;
• The valid years are 2019, 2020, 2021, 2022 (inclusive);
• The valid months are between 1 and 12 (inclusive);
• The valid days are between 1 and 31 (inclusive);

const char* name() const: a query that returns the address of the first name of the traveler; OR the address of an empty string if the Traveler object is in a safe empty state.

bool canTravelWith(const Traveler&) const: a query that receives an unmodifiable reference to a Traveler object and checks if the traveler referenced can travel with the current Traveler (two traveler can travel together if they are flying to the same destina-tion on the same date).

Modify your implementations of the constructor and display() member func-tions to include the date of departure in the format shown below (see also the output listing below):

default constructor (a no-argument constructor): this constructor sets the object to a safe empty state, including the date variables;

constructor with 3 parameters: Same parameters as for in-lab portion. This constructor copies this data from parameters into the instance variables and sets the departure date to July 1st, 2019, only if the data is valid. Data is valid if the address refers to a non-empty string; that is, data is not valid if its address is the null address or the string at that address is empty. If the data is not valid, this con-structor sets the object to a safe empty state.

void display() const: a query that displays the contents of the Traveler object in the following format (see also the output listing below). Note that the month and day values are in two-digit for-mat zero-filled if necessary

LAST-NAME, FIRST-NAME goes to DESTINATION on YEAR/MM/DD< ENDL>

Using the w4_at_home.cpp implementation file of the main module shown below, test your code and make sure that it works correctly. Below the source code is the expected output from your program. The output of your program should match exactly the expected one.

AT-HOME MAIN MODULE

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

using namespace std;
using namespace sict;

int main()
{
Traveler travelers[] = {
Traveler(nullptr, "Smith", "Toronto", 2020, 4, 20),
Traveler("", "Smith", "Toronto", 2020, 4, 20),
Traveler("John", "", "Toronto", 2020, 4, 20),
Traveler("John", "Smith", nullptr, 2020, 4, 20),
Traveler("John", "Smith", "", 2020, 4, 20),
Traveler("John", "Smith", "Toronto", 2020, 4, 20), // valid
Traveler("John", "Smith", "Toronto", 2028, 4, 20),
Traveler("John", "Smith", "Toronto", 2014, 4, 20),
Traveler("John", "Smith", "Toronto", 2022, 12, 31), // valid
Traveler("John", "Smith", "Toronto", 2020, 40, 20),
Traveler("John", "Smith", "Toronto", 2020, 0, 20),
Traveler("John", "Smith", "Toronto", 2019, 1, 1), // valid
Traveler("John", "Smith", "Toronto", 2020, 4, 0),
Traveler("John", "Smith", "Toronto", 2020, 4, 32),
Traveler(nullptr, nullptr, nullptr, 0, 0, 0),
Traveler("John", "Smith", "Toronto"), // valid
Traveler()
};
cout << "----------------------------------------" << endl;
cout << "Testing the validation logic" << endl;
cout << "(only travelers 6, 9, 12 and 16 should be valid)" << endl;
cout << "----------------------------------------" << endl;
for (int i = 0; i < 17; ++i)
{
cout << "Traveler " << i + 1 << ": "
<< (travelers[i].isEmpty() ? "not valid" : "valid") << endl;
}
cout << "----------------------------------------" << endl << endl;

Traveler david("David", "Davis", "Toronto", 2019, 6, 20);
Traveler friends[] = {
Traveler("Vanessa", "Miller", "Toronto", 2019, 6, 20),
Traveler("John", "Miller", "Toronto", 2019, 6, 6),
Traveler("Alice", "Turner", "Toronto", 2019, 10, 20),
Traveler("Bob", "Moore", "Paris", 2019, 6, 20),
Traveler("Jennifer", "Hill", "Toronto", 2020, 6, 20),
Traveler("Mike", "Flores", "Toronto", 2019, 6, 20),
Traveler("Sarah", "Stewart", "Toronto", 2019, 6, 20),
Traveler("Mark", "Simmons", "Toronto")
};

cout << "----------------------------------------" << endl;
cout << "Testing Traveler::display(...)" << endl;
cout << "----------------------------------------" << endl;
for (int i = 0; i < 8; ++i)
friends[i].display();
cout << "----------------------------------------" << endl << endl;

cout << "----------------------------------------" << endl;
cout << "Testing Traveler::canTravelWith(...)" << endl;
cout << "----------------------------------------" << endl;
cout << david.name() << " can travel with: " << endl;
for (int i = 0; i < 8; ++i)
{
if (david.canTravelWith(friends[i]))
cout << " - " << friends[i].name() << endl;
}
cout << "----------------------------------------" << endl << endl;

return 0;
}

AT-HOME EXPECTED OUTPUT

----------------------------------------
Testing the validation logic
(only travelers 6, 9, 12 and 16 should be valid)
----------------------------------------
Traveler 1: not valid
Traveler 2: not valid
Traveler 3: not valid
Traveler 4: not valid
Traveler 5: not valid
Traveler 6: valid
Traveler 7: not valid
Traveler 8: not valid
Traveler 9: valid
Traveler 10: not valid
Traveler 11: not valid
Traveler 12: valid
Traveler 13: not valid
Traveler 14: not valid
Traveler 15: not valid
Traveler 16: valid
Traveler 17: not valid
----------------------------------------

----------------------------------------
Testing Traveler::display(...)
----------------------------------------
Miller, Vanessa goes to Toronto on 2019/06/20
Miller, John goes to Toronto on 2019/06/06
Turner, Alice goes to Toronto on 2019/10/20
Moore, Bob goes to Paris on 2019/06/20
Hill, Jennifer goes to Toronto on 2020/06/20
Flores, Mike goes to Toronto on 2019/06/20
Stewart, Sarah goes to Toronto on 2019/06/20
Simmons, Mark goes to Toronto on 2019/07/01
----------------------------------------

----------------------------------------
Testing Traveler::canTravelWith(...)
----------------------------------------
David can travel with:
- Vanessa
- Mike
- Sarah
----------------------------------------

REFLECTION

Study your final solution, reread the related parts of the course notes, and make sure that you have understood the concepts covered by this workshop. This should take no less than 30 minutes of your time.

Create a file named reflect.txt that contains your detailed description of the topics that you have learned in completing this workshop and mention any issues that caused you difficulty. Include in your explanationbut do not limit it tothe following points:

1)What is a safe empty state? Could you define another state as the safe emp-ty state?

2)Describe how you have minimized code duplication.

3)Explain why the canTravelWith(...) member function can access the pri-vate data of the object referenced in its parameter.