Announcements
 Homework 5 – Robot game will be assigned this week
 Due in 2 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.
Midterm 1 Grades
 To be announced TOMORROW
 You may see your papers (Thursday)
 At 11:40-13:30 in FENS class to be announced
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
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
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.
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
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 ();
Destructor (not needed in HW5)
void Move (int distance = 1);
bool Blocked ();
void TurnRight ();
bool PickThing ();
bool PutThing ();
member
void SetColor (Color color);
functions
bool FacingEast ();
bool FacingWall ();
bool CellEmpty ();
bool BagEmpty ();
continued on the next slide
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;
pointers for the data structure
you will not need them
friend struct RobotWindow;
};
RobotWindow may refer
Robot’s private data
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);
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
The class 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
Constructing Date objects – see
usedate.cpp
Date
Date
Date
Date
cout
cout
today;
republic(10,29,1923);
million(1000000);
y2k(1,1,2000);
<< "today: " << today << endl;
<< "Republic of Turkey has been founded on: "
<< republic << endl;
cout << "millionth day: " << million << endl;
OUTPUT
today: April 4 2016
Republic of Turkey has been founded on: October 29 1923
millionth day: November 28 2738
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
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
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
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 ???
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
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