RIS214. Class Test 3

Transcription

1 RIS214 Class Test 3 Use console applications to solve the following problems and employ defensive programming to prevent run-time errors. Every question will be marked as follows: mark = copied? -5 : runs? 2 : good attempt? 1 : 0; if (Sum(marks) < 0) assignment is incomplete resubmit entire assignment if (mark for resubmit > 50%) mark = 0 else assignment is incomplete if (second assignment incomplete) module is incomplete Come back next year Please read the departmental disciplinary code on the csi server. If you are found guilty of plagiarism (dealer or stealer), you will get incomplete for this assignment and you will have to resubmit. If your resubmitted program does not run correctly you will get an incomplete for the module. Come back next year. Remember that these weekly exercises are exercises. The more time you spend, the easier you will find the tests and exam. Submit before Wednesday 26 February 17:00. Section A (Operator overloading) 1. Consider the basic class for fractions that was discussed in class. Make provision for all types of exceptions. 1.1 Expand the class to make provision for the operators: -, *, /, ==,!=, >, <, Equals (unary) 1.2 Provide a method ToDouble() that will return the double equivalent of the fraction. 1.3 Provide a method, Parse(), which will take string input and instantiate a new instance of the class Fraction. Use hard coded values and expressions in the Main() method to test all operators and methods. static void Main() //Input Fraction f1 = new Fraction(3, 6); Fraction f2 = Fraction.Parse("1/3"); 1

2 //Return as decimals Console.WriteLine(f1.ToString() + " = " + f1.todouble().tostring()); Console.WriteLine(f2.ToString() + " = " + f2.todouble().tostring()); //Basic operations Fraction f3 = f1 + f2; Console.WriteLine(f1.ToString() + " + " + f2.tostring() + " = " + f3.tostring()); f3 = f1 - f2; Console.WriteLine(f1.ToString() + " - " + f2.tostring() + " = " + f3.tostring()); f3 = f1 * f2; Console.WriteLine(f1.ToString() + " * " + f2.tostring() + " = " + f3.tostring()); f3 = f1 / f2; Console.WriteLine(f1.ToString() + " / " + f2.tostring() + " = " + f3.tostring()); //Comparisons Console.WriteLine(f1 == f2? f1.tostring() + " = " + f2.tostring() : f1.tostring() + " <> " + f2.tostring()); Console.WriteLine(f1.Equals(f2)? f1.tostring() + " equals " + f2.tostring() : f1.tostring() + " not equal to " + f2.tostring()); Console.WriteLine(f1 > f2? f1.tostring() + " > " + f2.tostring() : f1 < f2? f1.tostring() + " < " + f2.tostring() : f1.tostring() + " = " + f2.tostring() ); Console.Write("Press any key to exit..."); //Main Section B (Generics and Indexers) 2. Develop a generic method that will accept a list of elements of any type and print all elements to the screen. Provide and implement several test cases. 3. Develop a generic class called Stock. The class should privately store the name of the stock, the current value of the stock and the value the stock was previously (default: 0). The class should contain a suitable constructor, a method to set the current value of the stock and override ToString() so that when it is called the class returns the current and previous value of the stock as well as the stocks name. In Main() create three instances of Stock: an int, decimal and long version. Use ToString() to write to console the stock values, change the current value then write to console once again. Ensure that the previous value of the stock is kept. Section C (Project) 4. Do number 22 in Nakov, page 616 and 618. Use an enum for the names of disciplines. Create a class CSchool with nested classes for CSchoolClass, CStudent, CTeacher, CDiscipline. Define generic lists for school classes, students, and teachers. Use serialisation to save your data (see the extra notes given to you last year as part of Chapter 13 of Blignaut or page 262 in the 2014 version of Blignaut). Use a menu driven application from a console application. Provide for reports with students in a class, classes taught by a teacher, etc. Be creative and see how much detail you can add. You may work together in groups for this one. List the names of all group members together with his/her contribution in a comment block at the top of every class. The contribution is expressed as a percentage of the input provided by the person who contributed the most. For example if A did the most, he gets 100%. If B did about 80% of the amount of work that A did, he gets 80%. The same for the other team members. I trust your integrity. Don t disappoint me. 2

3 SOLUTIONS Question 1 class Fraction //Fields private int numerator; private int denominator; // Constructor public Fraction(int numerator, int denominator) if (denominator == 0) throw new Exception("Cannot have zero denominator."); this.numerator = numerator; this.denominator = denominator; //Reduce(); //Constructor //Parse public static Fraction Parse(string s) string snumerator = s.substring(0, s.indexof("/")); string sdenominator = s.substring(s.indexof("/")+1); int numerator, denominator; if (int.tryparse(sdenominator, out denominator) && int.tryparse(snumerator, out numerator)) return new Fraction(numerator, denominator); else return new Fraction(0, 1); //Parse //Operators public static Fraction operator + (Fraction f1, Fraction f2) Fraction f = new Fraction(f1.numerator * f2.denominator + f2.numerator * f1.denominator, f1.denominator * f2.denominator); return f.reduce(); //operator + public static Fraction operator - (Fraction f1, Fraction f2) Fraction f = new Fraction(f1.numerator * f2.denominator - f2.numerator * f1.denominator, f1.denominator * f2.denominator); return f.reduce(); //operator - public static Fraction operator * (Fraction f1, Fraction f2) Fraction f = new Fraction(f1.numerator * f2.numerator, f1.denominator * f2.denominator); return f.reduce(); //operator * public static Fraction operator / (Fraction f1, Fraction f2) Fraction f = new Fraction(f1.numerator * f2.denominator, f1.denominator * f2.numerator); return f.reduce(); //operator / //Comparisons public static bool operator == (Fraction f1, Fraction f2) return (f1.numerator == f2.numerator && f1.denominator == f2.denominator); 3

4 public static bool operator!=(fraction f1, Fraction f2) return!(f1 == f2); public bool Equals(Fraction f) return (this.numerator == f.numerator && this.denominator == f.denominator); public static bool operator > (Fraction f1, Fraction f2) return f1.numerator * f2.denominator > f2.numerator * f1.denominator; public static bool operator <(Fraction f1, Fraction f2) return f1.numerator * f2.denominator < f2.numerator * f1.denominator; //Convert to double public double ToDouble() return numerator * 1.0 / denominator; // Reduce fraction to simplest form private Fraction Reduce() Fraction f = new Fraction(1, 1); int gcd = Math.Abs(numerator) > Math.Abs(denominator)? Math.Abs(denominator) : Math.Abs(numerator); if (gcd == 0) return this; while (!(numerator % gcd == 0 && denominator % gcd == 0)) gcd--; f.numerator = numerator / gcd; f.denominator = denominator / gcd; return f; //Reduce // Display public override String ToString() if (numerator == 0) return "0"; String sign = ""; if (numerator * denominator < 0) sign = "-"; if (denominator == 1) return sign + Math.Abs(numerator); return sign + Math.Abs(numerator) + "/" + Math.Abs(denominator); //ToString() //CFraction 4

5 Question 2 class Program static void Main(string[] args) //List of ints List<int> lstintegers = new List<int>(); lstintegers.addrange(new int[] 4, 7, 8, 9, 2, 4 ); Print<int>(lstIntegers); //List of strings List<string> lstnames = new List<string>(); lstnames.addrange(new string[] "John", "Mike", "Susan", "Abel", "Henri", "Dan" ); Print<string>(lstNames); //List of students List<CStudent> lststudents = new List<CStudent>(); lststudents.add(new CStudent("123", "John")); lststudents.add(new CStudent("345", "Mike")); lststudents.add(new CStudent("234", "Sarel")); lststudents.add(new CStudent("345", "Peet")); Print<CStudent>(lstStudents); //Opportunity to read output //Main static void Print<T>(List<T> list) foreach (T element in list) Console.WriteLine(element); //Print //class Program class CStudent public string StudentNumber get; set; public string StudentName get; set; public CStudent(string Number, string Name) StudentNumber = Number; StudentName = Name; public override string ToString() return StudentNumber + ", " + StudentName; //class CStudent 5

6 Question 3 class Program static void Main(string[] args) Stock<int> ComputerStock = new Stock<int>(20, "Computer INC"); Stock<decimal> RetailStock = new Stock<decimal>(14.33m, "Pick and Pray"); Stock<double> UFSStock = new Stock<double>( d, "UFS"); Console.WriteLine(UFSStock.ToString()); Console.WriteLine(RetailStock.ToString()); Console.WriteLine(ComputerStock.ToString()); ComputerStock.SetValue(30); RetailStock.SetValue(22.5m); UFSStock.SetValue(15.333d); Console.WriteLine(UFSStock.ToString()); Console.WriteLine(RetailStock.ToString()); Console.WriteLine(ComputerStock.ToString()); Console.ReadLine(); //Main //class Program public class CStock <T> private T Value; private T PreviousValue get; set; private string StockName get; set; public CStock(T value, string StockName) this.value = value; this.stockname = StockName; public void SetValue(T value) this.previousvalue = this.value; this.value = value; public override string ToString() return "Value of " + this.stockname +" was " + this.previousvalue + " and is now " + this.value; //clas CStock 6

7 Question 4 Below is one possible solution. This exercise was left open ended and you could have implemented it in any way that you thought would work. I tried to model a primary school where all students have the same set of subjects and stay in the same class for the entire year. In other words, a student belongs to one class only. Teachers who teach in different classes had to be entered spearately for all classes. I know that this is not always realistic, but we have to make some assumptions to keep the design simple. enum Disciplines Accounting, Afrikaans, English, History, IT, LifeSkills, Maths, Science //enum Disciplines [Serializable] class CSchool //Students [Serializable] public class CStudent public string Number get; set; public string Name get; set; //class CStudent //public List<CStudent> lststudents get; private set; //Classes [Serializable] public class CSchoolClass public string classidentifier; public List<CTeacher> lstteachers; public List<CStudent> lststudents; public CSchoolClass() lstteachers = new List<CTeacher>(); lststudents = new List<CStudent>(); //class CSchoolClass public List<CSchoolClass> lstclasses get; private set; //Teachers [Serializable] public class CTeacher public string Name get; set; public List<CDiscipline> lstdisciplines; public CTeacher() lstdisciplines = new List<CDiscipline>(); //class CTeacher //Disciplines [Serializable] public class CDiscipline public Disciplines Name; int NumberOfLessons; int NumberOfExercises; //class CDiscipline //Constructor public CSchool() lstclasses = new List<CSchoolClass>(); //class CSchool 7

8 class Program static CSchool School; #region Main and Menu static void Main(string[] args) School = new CSchool(); Read(); //Read data from disk Menu(); //Display menu first time //Main private static void Menu() Console.WriteLine("1. Enter classes"); Console.WriteLine("2. List classes"); Console.WriteLine("3. Enter teachers per class"); Console.WriteLine("4. List teachers per class"); Console.WriteLine("5. List classes per teacher"); Console.WriteLine("6. Enter students per class"); Console.WriteLine("7. List students per class"); Console.WriteLine("X. Exit"); Console.Write("\nSelect: "); char option = Console.ReadKey().KeyChar.ToString().ToUpper()[0]; switch (option) case '1': EnterClasses(); Menu(); break; case '2': ListClasses(); Menu(); break; case '3': EnterTeachersPerClass(); Menu(); break; case '4': ListTeachersPerClass(); Menu(); break; case '5': ListClassesPerTeacher(); Menu(); break; case '6': EnterStudentsPerClass(); Menu(); break; case '7': ListStudentsPerClass(); Menu(); break; case 'X': Save(); break; default: Menu(); break; //Menu #endregion Main and Menu #region Serialize private static void Save() FileStream fs = new FileStream("School.bin", FileMode.Create); IFormatter formatter = new BinaryFormatter(); formatter.serialize(fs, School); fs.close(); //Save private static void Read() if (File.Exists("School.bin")) FileStream fs = null; fs = new FileStream("School.bin", FileMode.Open); IFormatter formatter = new BinaryFormatter(); School = (CSchool)formatter.Deserialize(fs); fs.close(); //Read #endregion Serialize 8

9 #region School classes private static void EnterClasses() //if (School.lstClasses == null) // School.lstClasses = new List<CSchool.CSchoolClass>(); string sidentifier = ""; do Console.Write("Class name (x to exit): "); sidentifier = Console.ReadLine(); if (sidentifier.toupper()!= "X") School.lstClasses.Add(new CSchool.CSchoolClass classidentifier = sidentifier ); while (sidentifier.toupper()!= "X"); //EnterClasses private static void ListClasses() foreach (CSchool.CSchoolClass class_ in School.lstClasses) Console.WriteLine(class_.classIdentifier); //ListClasses #endregion School classes 9

10 #region Teachers per class private static void EnterTeachersPerClass() Console.Write("Class: "); string sclass = Console.ReadLine(); CSchool.CSchoolClass class_ = School.lstClasses.First(cl => cl.classidentifier == sclass); if (class_!= null) string sname = ""; do Console.Write("Teacher name (x to exit): "); sname = Console.ReadLine(); if (sname.toupper()!= "X") CSchool.CTeacher teacher = new CSchool.CTeacher Name = sname ; string sdiscipline = ""; do Console.Write("Discipline (x to exit): "); sdiscipline = Console.ReadLine(); if (sdiscipline.toupper()!= "X") Disciplines Discipline = (Disciplines)Enum.Parse(typeof(Disciplines), sdiscipline); teacher.lstdisciplines.add(new CSchool.CDiscipline Name = Discipline ); while (sdiscipline.toupper()!= "X"); class_.lstteachers.add(teacher); while (sname.toupper()!= "X"); //if class_!= null //EnterTeachersPerClass private static void ListTeachersPerClass() Console.Write("Class: "); string sclass = Console.ReadLine(); CSchool.CSchoolClass class_ = School.lstClasses.First(cl => cl.classidentifier == sclass); foreach (CSchool.CTeacher teacher in class_.lstteachers) Console.Write(teacher.Name + "\t"); foreach (CSchool.CDiscipline discipline in teacher.lstdisciplines) Console.Write(discipline.Name.ToString() + ", "); //foreach teacher //ListTeachersPerClass 10

11 private static void ListClassesPerTeacher() Console.Write("Teacher: "); string steacher = Console.ReadLine(); foreach (CSchool.CSchoolClass class_ in School.lstClasses) foreach (CSchool.CTeacher teacher in class_.lstteachers) if (teacher.name == steacher) Console.WriteLine(class_.classIdentifier); //ListClassesPerTeacher #endregion teachers per class #region Students per class private static void EnterStudentsPerClass() Console.Write("Class: "); string sclass = Console.ReadLine(); CSchool.CSchoolClass class_ = School.lstClasses.First(cl => cl.classidentifier == sclass); if (class_!= null) string snumber = ""; do Console.Write("Student number (x to exit): "); snumber = Console.ReadLine(); if (snumber!= "x") Console.Write("Student name: "); string sname = Console.ReadLine(); class_.lststudents.add(new CSchool.CStudent Number = snumber, Name = sname ); while (snumber!= "x"); //if class_!= null //EnterStudents private static void ListStudentsPerClass() Console.Write("Class: "); string sclass = Console.ReadLine(); CSchool.CSchoolClass class_ = School.lstClasses.First(cl => cl.classidentifier == sclass); foreach (CSchool.CStudent student in class_.lststudents) Console.WriteLine(student.Number + "\t" + student.name); //ListStudents #endregion Students per class //class Program 11