This is an open-book test. You may use the text book Be Sharp with C# but no other sources, written or electronic, will be allowed.

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1 UNIVERSITY OF THE FREE STATE DEPARTMENT OF COMPUTER SCIENCE AND INFORMATICS RIS 124 DATE: 1 September 2014 TIME: 3 hours MARKS: 105 ASSESSORS: Prof. P.J. Blignaut BONUS MARKS: 3 MODERATOR: Dr. L. De Wet This is an open-book test. You may use the text book Be Sharp with C# but no other sources, written or electronic, will be allowed. Question 1 Write a console application that will allow the user to enter a positive binary number as a character string and then display the equivalent decimal value. The number may have a fractional part. Display an appropriate message if the user enters an invalid binary number. Use a sentinel-controlled loop to convert several numbers until the user enters -1. Study the example output below. Hint: = 1x x x x x x2-2 = [23] Question 2 Develop a Windows forms application as in the example that will allow a user to enter a character string in a text box. If the user clicks the Encode button, the given string must be encoded using a key (hard coded). If the user clicks the Decode button, the given string must be decoded. All characters must be converted to upper case first. You can test your application by entering a string into the box and encode it. Using the encoded string as input, your program should correctly decode it to return the original string if you click the Decode button. The encoding is done by replacing every character in the alphabet with the corresponding letter in a key string. Consider, for example, the following: 1

2 Letters: "ABCDEFGHIJKLMNOPQRSTUVWXYZ., " Key : "KBDFAGXUHIJVLZNEOPRMSTCWQY., " For example, "John is sick" will become "INUZ HR RHDJ". [16] Question 3 Consider the following special definition: Two integer arrays, A and B, are considered to be friends if an element in B is a multiple of the corresponding element in A. For example, 2, 5, 3, 7, 6 and 4, 15, 3, 21, 30 are friends but 2, 5, 3, 7, 6 and 4, 9, 6, 14, 12 are not friends because 9 is not a multiple of 5. Of course, arrays can only be friends if they have the same length. Develop a console application that will do compile time initialisation of the two arrays and determine if they are friends or not. [15] Question 4 Start with a new console application. 4.1 Define a class, CShoe, with private data members for the size (double), gender (char)and colour (string). (4) 4.2 Define properties for the data members that will enforce the following restrictions: - Gender must be restricted to 'M' or 'F' or 'U' (for "Male", "Female" or "Unisex"). Assign ' ' otherwise. (8) - The shoe size must be limited to Half sizes are acceptable, but not other fractions. In other words, 5 and 4.5 is OK, but 4.3 is not acceptable. Assign 0 if the size is invalid. (8) - Men's shoes may only be "Brown", "Black" or "Grey". Ladies shoes may only be "Black" or "White" or "Red". Shoe for men and ladies may only be "Black". Assign "Invalid colour" otherwise. (9) 4.3 Add a constructor to instantiate a shoe object with default properties, Size = 4, Gender = 'M' and Colour = "Black". (5) 4.4 Add another constructor that will initialise the properties with values provided as parameters. (5) 2

3 4.5 Override the built-in ToString() method to return a string as in the examples: - "Mens, Size 10, Grey" - "Ladies, Size 6.5, Red" (8) 4.6 Add a static method, Add, to the class that will take 2 CShoe parameters, shoe1 and shoe2, and return a CShoe. The resulting shoe should be constructed as follows: Size = Min(shoe1.size + shoe2.size, 14) Colour: If the colours are the same, then the colour of shoe1, else "Black". Gender: If the genders are the same, then the gender of shoe1, else 'U'. (7) 4.7 Copy and paste the following code into your Main method to test your class: static void Main(string[] args) Console.WriteLine(); CShoe shoe1 = new CShoe(); shoe1.colour = "Yellow"; shoe1.colour = "Brown"; shoe1.size = 9.3; shoe1.size = 9.5; shoe1.gender = 'X'; shoe1.gender = 'M'; Console.WriteLine(); CShoe shoe2 = new CShoe('F', 6,"White"); Console.WriteLine("\tShoe 2: " + shoe2); Console.WriteLine(); Console.WriteLine("\tShoe 1 + Shoe 2: " + CShoe.Add(shoe1, shoe2).tostring()); Console.ReadKey(); //Main The output of your program should look like this: [54] 3

4 Memorandum Question 1 static void Main(string[] args) //Declare string sbinary = ""; //Continue until the user presses -1 do //Input Console.Write("\n\tBinary number (-1 to end): "); sbinary = Console.ReadLine(); //Check for -1 if (sbinary!= "-1") //Check validity //- Remove all valid digits. Check if the string is now empty. if (sbinary.replace("1", "").Replace("0","").Replace(".", "")!= "") Console.WriteLine("\tInvalid binary number."); else //Valid - go ahead //Add decimal point if there is not one if (sbinary.indexof('.') == -1) sbinary += '.'; //Get position of decimal point int ipospoint = sbinary.indexof('.'); //Declare and initialise decimal value double ddecimal = 0; //Accumulate digits before the decimal point for (int i = 0; i < ipospoint; i++) ddecimal += int.parse(sbinary[i].tostring()) * Math.Pow(2, ipospoint-i-1); //Accumulate digits after the decimal point for (int i = ipospoint + 1; i < sbinary.length; i++) ddecimal += int.parse(sbinary[i].tostring()) * Math.Pow(2, -(i-ipospoint)); //Output Console.WriteLine("\tDecimal value: " + ddecimal); //if valid //if (sbinary!= "-1") while (sbinary!= "-1"); //Main 4

5 Question 2 Form layout Naming of form and controls Question 3 private void btnencode_click(object sender, EventArgs e) string sletters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ "; string skey = "KBDFAGXUHIJVLZNEOPRMSTCWQY "; string sencoded = ""; for (int i = 0; i < txtoriginal.text.length; i++) sencoded += skey[sletters.indexof(txtoriginal.text.toupper()[i])]; lbloutput.text = sencoded; //btnencode_click private void btndecode_click(object sender, EventArgs e) string sletters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ "; string skey = "KBDFAGXUHIJVLZNEOPRMSTCWQY "; string sdecoded = ""; for (int i = 0; i < txtoriginal.text.length; i++) sdecoded += sletters [skey.indexof(txtoriginal.text.toupper()[i])]; lbloutput.text = sdecoded; //btndecode_click static void Main(string[] args) int[] A = new int[] 2, 5, 3, 7, 6 ; int[] B = new int[] 4, 9, 3, 21, 30 ; bool isfriends = A.Length == B.Length; if (isfriends) int i = 0; while (i < A.Length && isfriends ) if (B[i] % A[i]!= 0) isfriends = false; i++; Console.WriteLine("Is friends: " + isfriends.tostring() ); Console.ReadKey(); //Main 5

6 Question class CShoe 4.1 private char chgender; 4.2 public char Gender get return chgender; set value = value.tostring().toupper()[0]; if (value == 'M' value == 'F' value == 'B') chgender = value; else chgender = ' '; //Gender 4.1 private double dsize; 4.2 public double Size get return dsize; set if (value >= 4 && value <= 14 && value * 2 == (int)(value * 2)) dsize = value; else dsize = 0; //Size 4.1 private string scolour; 4.2 public string Colour get return scolour; set if ( (Gender == 'M' && "BROWN,BLACK,GREY".Contains(value.ToUpper())) (Gender == 'F' && "BLACK,WHITE,RED".Contains(value.ToUpper())) (Gender == 'B' && "BLACK".Contains(value.ToUpper())) ) scolour = value; else scolour = "Invalid colour"; //Colour 4.3 public CShoe() this.gender = 'M'; this.size = 4; this.colour = "Black"; //CShoe 4.4 public CShoe(char Gender_, double Size_, string Colour_) this.gender = Gender_; this.size = Size_; this.colour = Colour_; //CShoe 6

7 4.5 public override string ToString() string sgender = Gender == 'M'? "Mens" : Gender == 'F'? "Ladies" : Gender == 'B'? "Both" : "Gender not defined"; return sgender + ", Size " + Size + ", " + Colour; //ToString 4.6 public static CShoe Add (CShoe shoe1, CShoe shoe2) char Gender = shoe1.gender == shoe2.gender? shoe1.gender : 'B'; string scolour = shoe1.colour == shoe2.colour? shoe1.colour : "Black"; double dsize = Math.Min(shoe1.Size + shoe2.size, 14); return new CShoe(Gender, dsize, scolour); //Add //class 7