UNIVERSITY OF THE FREE STATE DEPARTMENT OF COMPUTER SCIENCE AND INFORMATICS CSIS2614 MODULE TEST 1

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1 UNIVERSITY OF THE FREE STATE DEPARTMENT OF COMPUTER SCIENCE AND INFORMATICS CSIS2614 MODULE TEST 1 DATE: 18 March 2016 MARKS: 165 ASSESSOR: Prof. P.J. Blignaut (Bonus 8) MODERATOR: Dr T. Beelders TIME: 4 hours This is a limited open-book test. You may use ONLY the text book by Nakov. No other sources are allowed. Internet access will not be available for the duration of the assessment. You may use the tools available in Visual Studio such as IntelliSense. No mobile computing devices may be active for the duration of the assessment (Mobile phones, tablets, etc). Question 1 (Recursion) (12) If you stand in front of two opposite mirrors of the same size, your image in the first mirror is reflected in the second mirror which is in turn reflected in the first mirror, etc. Given your height and the ratio of reflection (hard code if you want to), use recursion to calculate the size of your image after 10 reflections. [12] 1

2 Question 2 (Operator overloading, Indexers) (111) In a marathon race, a team consists of four athletes. The team prize is awarded by using the combined time of the best three runners in a team. The main method of a program will be given to you. You may not change the code in any way. The output of the program should look as in the example: 2.1 You may not use the DateTime class. Develop your own class Time. (1) Include: - Constructors to accept time as a string in the format HH:mm:ss or as three int parameters for hours, minutes and seconds. (8) - Private data members for hours, minutes and seconds. (2) - An overloaded ToString() method to display a time in the format HH:mm:ss. (4) - The class must inherit from IComparable and implement the following method: (1) public int CompareTo(object t) return this < (Time)t? -1 : this > (Time)t? 1 : 0; //CompareTo - Overloaded operators for +, > and <. Make provision for null instances. ( ) - A static method Sort to sort an array of times in increasing order. Use a recursive selection sort technique as in the following high-level algorithm: (10) Sort(times, from, to) if (from!= to) indexofmax = Get index of largest time in the array times Swap times[to] with times[indexofmax] Sort(times, from, to-1); 2.2 Develop a class CAthlete. (1) - Include properties for the race number, athlete name and race time.(3)use the constructor to assign values for the race number and athlete name. Assign a default race time of 59 hours, 59 minutes and 59 seconds. This is the time that will be used if an athlete does not complete the race. (6) 2.3 Develop a class for CTeam (1) - Include properties for the team name and an array of four athletes. Use the constructor to assign values as necessary. (8) - Include an indexer that will return an individual athlete by his race number. (9) - Include a read-only property to return the combined time of the first three athletes in the team. Use the class Time that you developed earlier. (13) 2.4 Develop a class CTeams with a private list of teams. (5) - Add methods to add a team and return the number of teams. (8) - Add an indexer to return a team by index. (5) - Add a method to sort the teams according to their combined times. You may use Linq. (5) [111] Question 3 (Delegates and events) (50) 2

3 Develop a Windows forms application to simulate a car s instrument panel. Use a separate class for the car with private properties for fuel level, distance travelled, etc. No numeric properties may be public. You may of course have public delegate types and events. (5) - The class must have a private recursive method, HandlePedal, which will change the speed depending on the current pedal status. It should also trigger events when the speed, distance or fuel level changes. These events must be handled in the form class. Make provision for the following minimum set of functionalities: Accelerate if the mouse is down on the + or ++ buttons (foot is pressing down lightly or heavily). (5) Keep the speed on the same level if the button is down on Steady (foot is keeping the pedal in the same place). (5) Decelerate light, firm or sharp if the mouse is on the -, -- or --- buttons (braking light, firm or sharp). (5) Decelerate slowly until the car stops if the mouse is not down on any button (foot is up). (5) Show the speed in the speedometer. (5) Keep track of the fuel. Remember that the consumption is higher (less km per litre) when the car moves faster. (5) Decelerate slowly until the car stops when the fuel is depleted. (5) Keep record of the current fuel and odometer reading if you park the car (go out of the program). Next time, start where you left off. (5+5) NB NB NB: You may never use any timer in the application!!! Marks will only be allocated for correct execution. You will get either 5 or 0 for any one of the above-mentioned functionalities. You will get zero for the entire question if there is a timer anywhere in the program. [50] 3

4 MEMORANDUM Question 1 class Program static int ndepth = 4; const double height = 1.8, ratio = 0.8; static void Main(string[] args) Console.WriteLine(Size(0, height).tostring()); Console.ReadKey(); //Main private static double Size(int n, double height) if (n == ndepth) return height; else return Size(n + 1, ratio * height); //Size //class Program 4

5 Question 2.1 (47) //Partial class for instance methods partial class Time : IComparable //Private data members private int hours, minutes, seconds; //Constructor 1 public Time(string stime) if (stime.length == 8) try hours = int.parse(stime.substring(0, 2)); minutes = int.parse(stime.substring(3, 2)); seconds = int.parse(stime.substring(6, 2)); catch hours = minutes = seconds = 59; //if else hours = minutes = seconds = 59; //Constructor //Constructor 2 public Time(int hours, int minutes, int seconds) this.hours = hours; this.minutes = minutes; this.seconds = seconds; if (hours + minutes + seconds == 0) hours = minutes = seconds = 59; //Time //Convert output to string public override string ToString() return hours.tostring().padleft(2, '0') + ":" + minutes.tostring().padleft(2, '0') + ":" + seconds.tostring().padleft(2, '0'); //ToString //Needed for IComparable public int CompareTo(object t) return this < (Time)t? -1 : this > (Time)t? 1 : 0; //CompareTo //partial class Time 5

6 //Partial class for static methods partial class Time public static Time operator +(Time t1, Time t2) int totalseconds1 = int.maxvalue; if (t1!= null) totalseconds1 = t1.hours * t1.minutes * 60 + t1.seconds; int totalseconds2 = int.maxvalue; if (t2!= null) totalseconds2 = t2.hours * t2.minutes * 60 + t2.seconds; int totalseconds = totalseconds1 + totalseconds2; int hours = totalseconds / 3600; totalseconds = totalseconds - hours * 3600; return new Time(hours, totalseconds / 60, totalseconds % 60); 7 //operator + public static bool operator > (Time t1, Time t2) int totalseconds1 = int.maxvalue; if (t1!= null) totalseconds1 = t1.hours * t1.minutes * 60 + t1.seconds; int totalseconds2 = int.maxvalue; if (t2!= null) totalseconds2 = t2.hours * t2.minutes * 60 + t2.seconds; return totalseconds1 > totalseconds2; x7 //operator > public static bool operator < (Time t1, Time t2) int totalseconds1 = int.maxvalue; if (t1!= null) totalseconds1 = t1.hours * t1.minutes * 60 + t1.seconds; int totalseconds2 = int.maxvalue; if (t2!= null) totalseconds2 = t2.hours * t2.minutes * 60 + t2.seconds; return totalseconds1 < totalseconds2; //operator < public static void Sort(Time[] times, int from, int to) if (from!= to) //Get index of max int indexofmax = 0; Time maxtime = times[indexofmax]; for (int i = 0; i <= to; i++) if (times[i] > times[indexofmax]) indexofmax = i; //Swap Time tmp = times[indexofmax]; times[indexofmax] = times[to]; times[to] = tmp; //Sort smaller array Sort(times, from, to - 1); //Sort //partial class 6

7 Question 2.2 (10) class CAthlete public string RaceNumber get; private set; public string Name get; private set; public Time time get; set; public CAthlete(string RaceNumber, string Name) this.racenumber = RaceNumber; this.name = Name; time = new Time(59, 59, 59); //CAthlete //class CAthlete Question 2.3 (31) class CTeam //Public data members public string Name get; private set; public CAthlete[] Athletes get; set; //Constructor public CTeam(string Name) this.name = Name; Athletes = new CAthlete[4]; Athletes[0] = new CAthlete("0", ""); Athletes[1] = new CAthlete("0", ""); Athletes[2] = new CAthlete("0", ""); Athletes[3] = new CAthlete("0", ""); //Indexer to get athlete public CAthlete this[string RaceNumber] get foreach (CAthlete athlete in Athletes) if (athlete.racenumber == RaceNumber) return athlete; return null; //this //Read-only property for total time of first three athletes public Time TotalTime get Time total = new Time(0, 0, 0); Time[] times = new Time[] Athletes[0].time, Athletes[1].time, Athletes[2].time, Athletes[3].time ; Time.Sort(times, 0, times.length - 1); for (int i = 0; i < 3; i++) total = total + times[i]; return total; //TotalTime //class CTeam 7

8 Question 2.4 (23) class CTeams //Private list of teams private List<CTeam> lstteams; //Constructor public CTeams() lstteams = new List<CTeam>(); //Constructor public void Add(CTeam team) lstteams.add(team); //Add public int Count() return lstteams.count; //Count //Indexer to return team public CTeam this[int i] get return lstteams[i]; //Indexer public void Sort() lstteams = lstteams.orderby(t => t.totaltime).tolist(); //Sort //class CTeams 8

9 Question 3 (50) public enum Pedal Break1, Break2, Break3, Petrol1, Petrol2, Petrol3, None public class CCar : IDisposable //To enable the Dispose event //Private members private int maxspeed; private double fuel; private double fuelcapacity ; private double distanceontank; private Pedal pedal; private CfrmCar frmparent; private bool ison = false; //Delegates public delegate void delspeedchanged(int speed); public delegate void delvaluechanged(double value); public delegate void delonstop(double fuel, double odo); //Events public event delspeedchanged SpeedChanged; public event delvaluechanged DistanceChanged; public event delvaluechanged FuelChanged; public event delonstop OnStop; //Constructor public CCar(CfrmCar frmparent, int maxspeed, double fuelcapacity) this.frmparent = frmparent; this.maxspeed = maxspeed; this.fuelcapacity = fuelcapacity; frmparent.pedaldown += frmparent_pedaldown; fuel = 50; distanceontank = 0; //Constructor public void Dispose() ison = false; frmparent.pedaldown -= frmparent_pedaldown; //Dispose public void Start(double fuel, double odo) this.fuel = fuel; this.distanceontank = odo; ison = true; HandlePedal(0); //First call //Start public void Stop() if (OnStop!= null) OnStop(fuel, distanceontank); ison = false; public void AddFuel(double fuel) this.fuel += fuel; if (this.fuel > fuelcapacity) this.fuel = fuelcapacity; Start(this.fuel, 0); private void frmparent_pedaldown(pedal pedal, bool isdown) this.pedal = isdown? pedal : Pedal.None; //frmparent_pedaldown 9

10 private void HandlePedal(int speed) switch (pedal) case Pedal.Break1: speed -= 2; break; //Light brake case Pedal.Break2: speed -= 4; break; //Firm brake case Pedal.Break3: speed -= 6; break; //Sharp brake case Pedal.Petrol1: speed += 0; break; //Keep constant case Pedal.Petrol2: speed += 2; break; //Steady accelerate case Pedal.Petrol3: speed += 4; break; //Fast accelerate default: speed -= 1; break; //Slow deceleration //switch //Speed if (speed < 0) speed = 0; if (speed > maxspeed) speed = maxspeed; //Distance double distancethisinterval = speed * 0.02; //s = v*t distanceontank += distancethisinterval; //Fuel if (speed > 0) double consumption = speed / 10.0; fuel -= distancethisinterval / consumption; if (fuel < 0) fuel = 0; pedal = Pedal.None; //Trigger events if (SpeedChanged!= null) SpeedChanged(speed); if (DistanceChanged!= null) DistanceChanged(Math.Round(distanceOnTank, 1)); if (FuelChanged!= null) FuelChanged(Math.Round(fuel, 1)); //Ensure that all event handlers are triggered before next execution of this method Application.DoEvents(); //Wait and repeat Thread.Sleep(200); if (ison) HandlePedal(speed); //Recursive call //HandlePedal //class CCar 10

11 public partial class CfrmCar : Form private CCar Car; public delegate void delpedaldown(pedal pedal, bool isdown); public event delpedaldown PedalDown; public CfrmCar() InitializeComponent(); //Constructor private void CfrmCar_Shown(object sender, EventArgs e) trbarspeed.maximum = 200; prbarfuel.maximum = 50; Car = new CCar(this, trbarspeed.maximum, prbarfuel.maximum); Car.SpeedChanged += delegate(int speed) lblspeed.text = speed.tostring(); trbarspeed.value = speed; ; Car.DistanceChanged += delegate(double distanceontank) lbldistanceontank.text = distanceontank.tostring(); ; Car.FuelChanged += delegate(double fuel) lblfuel.backcolor = (fuel < 10)? Color.Red : SystemColors.Control; lblfuel.text = fuel.tostring(); prbarfuel.value = Math.Min((int)fuel, prbarfuel.maximum); ; Car.OnStop += Car_OnStop; double fuel_ = 0, odo = 0; if (File.Exists("FuelOdo.txt")) StreamReader rdr = new StreamReader("FuelOdo.txt"); fuel_ = double.parse(rdr.readline()); odo = double.parse(rdr.readline()); rdr.close(); Car.Start(fuel_, odo); //CfrmCar_Shown private void Car_OnStop(double fuel, double odo) StreamWriter writer = new StreamWriter("FuelOdo.txt"); writer.writeline(fuel); writer.writeline(odo); writer.close(); //Car_OnStop private void CfrmCar_FormClosing(object sender, FormClosingEventArgs e) Car.Stop(); Car.Dispose(); //CfrmCar_FormClosing private void btnaddfuel_click(object sender, EventArgs e) Car.AddFuel(50); 11

12 #region event handlers for pedals 12 x 0.5 = 6 private void btnbreak1_mousedown(object sender, MouseEventArgs e) PedalDown(Pedal.Break1, true); private void btnbreak1_mouseup(object sender, MouseEventArgs e) PedalDown(Pedal.Break1, false); private void btnbreak2_mousedown(object sender, MouseEventArgs e) PedalDown(Pedal.Break2, true); private void btnbreak2_mouseup(object sender, MouseEventArgs e) PedalDown(Pedal.Break2, false); private void btnbreak3_mousedown(object sender, MouseEventArgs e) PedalDown(Pedal.Break3, true); private void btnbreak3_mouseup(object sender, MouseEventArgs e) PedalDown(Pedal.Break3, false); private void btnpetrol1_mousedown(object sender, MouseEventArgs e) PedalDown(Pedal.Petrol1, true); private void btnpetrol1_mouseup(object sender, MouseEventArgs e) PedalDown(Pedal.Petrol1, false); private void btnpetrol2_mousedown(object sender, MouseEventArgs e) PedalDown(Pedal.Petrol2, true); private void btnpetrol2_mouseup(object sender, MouseEventArgs e) PedalDown(Pedal.Petrol2, false); private void btnpetrol3_mousedown(object sender, MouseEventArgs e) PedalDown(Pedal.Petrol3, true); private void btnpetrol3_mouseup(object sender, MouseEventArgs e) PedalDown(Pedal.Petrol3, false); #endregion event handlers for pedals //class 12