1. Announcements Homework 3 – Robot game will be assigned this Friday
Due in 1.5 WEEKS  Start EARLY!
Common Questions:
Be aware of the flow of the game, read the document for all details
The flow of the game will repeat inside a big while loop until the game ends, we call one run of this loop a “turn” in the document:
Do not use TurnRight in TurnFace member function
Instead Turn the robot to a given direction by updating the private data member directly that you implemented for this HW in recitations
Submit ALL files in your project: main.cpp, robot_modified.cpp, robot_modified.h, minifw_modified.cpp, minifw_modified.h
Use the world.rw file in the homework zip to open an example world.

2. Midterm Grades To be announced NEXT WEEK Tuesday
You may see your papers on
Wednesday at 15:00-16:30 in FENS L030

3. Using, Understanding, Updating, Designing and Implementing Classes
Chapters 5 (5.4) and partially 6 and 7
in Chapter 6, up to 6.2.3
in Chapter 7
concepts of 7.1 and 7.2 are explained, but different examples are given
Robot class implementation details

4. RandGen Class A Tapestry class for random number generation
Add randgen.cpp to your project and have
#include "randgen.h" in your program
Four member functions
int RandInt(int max = INT_MAX);
returns a random integer in [0..max)
int RandInt(int low, int max);
returns a random integer in [low..max]
double RandReal();
returns a random double value in [0..1)
double RandReal(double low, double max);
returns a random double value in the range of [low..max]
see numberguess.cpp for an example program that use RandGen

5. Overloading
In RandGen class, there are two different functions named RandInt
so as RandReal
Using the same name for more than one function is called overloading.
They are differentiated by parameter types
Return types do not differentiate funtions
All member and free functions can be overloaded.

6. Implementation of Robot Class - 1
Your next homework will be about updating the Robot class
you will add some new member functions that requires to deal with robots.h and robots.cpp files (actually in the homework, you will use an updated class for which the file names are robots_modified.h and robots_modified.cpp)
and you will use those newly added functions in an application
It is a good idea to have a look at how this class is implemented
It is designed and implemented by Ersin Karabudak
We have made some changes later
Robot class implementation is quite complex
Robot, RobotWindow and RobotWorld are different structures
we will not deal with RobotWindow and RobotWorld, but the implementation file contains robot class implementation and the details of RobotWindow and RobotWorld too. Do not get confused.
Robots are maintained as a circular doubly linked list
it is a data structure that uses pointers (probably will see in CS300)
but do not get thrilled! you will not need those complex structures for the member functions that you will add.
Some details you have to know will be given now and more details will be given in recitations this week

7. Implementation of Robot Class - 2
enum Direction { east, west, north, south }; enum Color { white, yellow, red, blue, green, purple, pink, orange }; class Robot { public: Robot (int x, int y, Direction dir = east, int things = 0); ~Robot (); void Move (int distance = 1); bool Blocked (); void TurnRight (); bool PickThing (); bool PutThing (); void SetColor (Color color); bool FacingEast (); bool FacingWall (); bool CellEmpty (); bool BagEmpty ();
constructor
Destructor (not needed in HW5)
member
functions
continued on the next slide

8. Implementation of Robot Class - 3
private: int xPos; //x coordinate of the location of robot int yPos; //y coordinate of the location of robot Direction direction; //current direction of robot Color color; //current color of robot int bag; //current # of things in the bag of robot bool stalled; //true if the robot is dead bool visible; //true if the robot is visible Robot *next; Robot *prev; static Robot *list; friend struct RobotWindow; };
Private Data
pointers for the data structure
you will not need them
RobotWindow may refer
Robot’s private data

9. Implementation of Robot Class - 4
Previous two slides were in the robots.h (now robots_modified.h).
Now let’s go over the robots.cpp (now robots_modified.cpp) file in VC++ environment
In the next homework, you are going to add 6-8 member functions to the robot class
Some of the member functions will be done in recitations this week
Hints
try to use currently available member functions
e.g. for PickThings, try to use PickThing in a loop rather than writing some thing similar to PickThing
do not hesitate to modify or access private data members when needed
e.g. you will need such an update for TurnFace function
if you change the state of a robot within the current cell, use the following to update the window
theRobotWindow->Redraw(this);

10. Implementation of Robot Class - 5
Hints for the next homework (cont’d)
you will need to use the function called IsPressed defined in miniFW.h (it is going to be renamed as miniFW_modified.h)
so include this header file to your main program file
this function (IsPressed) is to check whether a key (e.g. an arrow key) is pressed or not - details are in recitations
Some other changes in the Robot World and Robot Class
If a robot hits another robot, both die!
No automatic message is displayed when a robot dies
Now the bag content is written in robots (if not zero)
Use robots_modified.h, robots_modified.cpp, miniFW_modified.h and miniFW_modified.cpp files in HW5
They will be provided to you in the homework and/or recitation package

11. The class Date The class Date models a calendar date:
The class Date is accessible to client programmers
#include "date.h"
to get access to the class
The compiler needs this information.
It may also contain documentation for the programmer
Link the implementation in date.cpp
Add this cpp to your project
The class Date models a calendar date:
Month, day, and year make up the state of a Date object
Dates can be printed, compared to each other, day-of-week determined, # days in month determined, many other behaviors
Behaviors are called methods or member functions

12. Constructing Date objects – see usedate.cpp
Date today;
Date republic(10,29,1923);
Date million( );
Date y2k(1,1,2000);
cout << "today: " << today << endl;
cout << "Republic of Turkey has been founded on: "
<< republic << endl;
cout << "millionth day: " << million << endl;
OUTPUT
today: April
Republic of Turkey has been founded on: October
millionth day: November

13. Constructing/defining an object
Date objects (as all other objects) are constructed when they’re first defined
Three ways to construct a Date
default constructor, no params, initialized to today’s date
single long int parameter, number of days from January 1, 1
three params: month, day, year (in this order).
Constructors for Date objects look like function calls
constructor is a special member function
Different parameter lists mean different constructors
Once constructed, there are many ways to manipulate a Date
Increment it using ++, subtract an integer from it using -, print it using cout, …
MonthName(), DayName(), DaysIn(), …
See date.h for more info on date constructors and member functions

14. Date Member Functions Date MidtermExam(27,3,2017);
Construct a Date object given month, day, year
MidtermExam.DayName()
Returns the name of the day (“Monday” or “Tuesday”, or ...)
in this particular case, returns “Monday” since December 1, 2014 is a Monday
MidtermExam.DaysIn()
Returns the number of days in the particular month
in our case return 31, since March 2017 has 31 days in it
Add, subtract, increment, decrement days from a date
Date GradesDue = MidtermExam + 9;
GradesDue is April 5, 2017
Let’s see usedate.cpp in full and datedemo.cpp now

15. Example: Father’s day (not in book)
Father’s day is the third Sunday of June
write a function that returns the date for the father’s day of a given year which is the parameter of the function
In main, input two years and display father’s days between those years
Date fathersday(int year)
// post: returns fathers day of year {
Date d(6,1,year); // June 1
while (d.DayName() != "Sunday")
d += 1; }
//d is now the first Sunday, 3rd is 14 days later
return d + 14;
See fathersday.cpp for full program

16. What if there were no date class?
It would be very cumbersome to deal with dates without a date class
imagine banking applications where each transaction has associated date fields
Classes simplify programming
they are designed and tested.
then they can be used by programmers
You are lucky if you can find ready-to-use classes for your needs
otherwise ???

17. Updating a Class (not in book)
Suppose you want to add more functionality to the date class
need to change the header file (date.h)
need to add implementation of new function(s) to date.cpp
Example: a new member function to calculate and return the remaining number of days in the object’s month
any ideas? do you think it is too difficult?
have a look at the existing member functions and see if they are useful for you

18. Updating a Class (not in book)
We can make use of DaysIn member function
Prototype in Date class (add to the header file)
int RemainingDays () const;
Implementation
int Date::RemainingDays () const {
return DaysIn() - myDay; }
In a member function implementation private data and other member functions referred without the dot operator.
They operate on the object for which the member function is called