1 Cpt S 321 – Exam 2 Spring 2019 40 points total Total pages: 12 Name: WSU ID: Seat in a way that there is at least one empty seat between you and your neighbors. - During the exam, if something is unclear, first ask for clarifications. If it is still unclear, then write down any assumptions that you are making. - Please DO NOT detach the sheets. - Allowed Tools: Pencil/pen, eraser - Use the last page (p.12) as a draft if needed. Anything you write there will not be corrected unless you explicitly ask me to do so when you are answering the questions. In that case annotate which part relates to which question. - There are 21 questions. (The last question accounts for 15 points) 2 Multiple Choice (1 point each) Write Answers Here ↓ 1. (1 point) Which of the following is true about design patterns? A. Design patterns represent the best practices used by experienced object- oriented software developers. B. Design patterns are solutions to general problems that software developers faced during software development C. Design patterns are obtained by trial and error by numerous software developers over quite a substantial period of time D. All of the above E. None of the above 2. (1 point) What pattern helps you to create lots of different kinds of objects? A. Proxy B. Command C. Adapter D. Strategy E. Factory 3. (1 point) What is one major difference between a struct and a class in C#? A. Default access modifier in struct is public, whereas it’s private for a class B. A struct is a reference type and a class is a value type C. A class is a reference type and a struct is a value type D. A struct cannot have member functions, but a class can E. A class cannot have member functions, but a struct can F. There is no difference 4. (1 point) A static function in a class: A. Can be executed without creating an instance of the class B. Cannot access member variables of the class C. Cannot call non-static member functions of the class D. All of the above A. None of the above 3 5. (1 point) Which of the following is the default access modifier for members? A. private B. protected C. public D. final E. internal F. There is no default access modifier 6. (1 point) If you have a sorted array and do a binary search for a value then the worst case is: A. You find the value, time is O(n) B. You don’t find the value, time is O(n) C. You find the value, time is O(log n) D. You don’t find the value, time is O(log n) E. Doesn’t matter if you find the value or not and the time cannot be determined without further information about the array contents 7. (1 point) A class is declared in a DLL class library. Which access/protection modifiers will allow it to be used by external applications that reference the DLL? (Assume reflection is NOT being used) A. public, internal, or protected B. public and internal C. internal only D. public only E. The access modifier is not what controls whether or not external applications can see and use it 8. (1 point) The event keyword in C# represents something that internally A. Is an expression tree B. Is a single integer value C. Is a single pointer value D. Is a list of function pointers/references 9. (1 point) What is the output obtained by executing Main? Code Output public static void Main() { string X = "42"; object Y = X.Replace("42", "101"); X = X.Replace("1", "2"); Console.WriteLine(Y);} 4 10. (1 points) What is the output obtained by executing Main? Code Output public static void Main() { string s = “Hello World!”; F2(ref s); Console.Write(s); } static void F2(ref string s) { s.Replace(“Hello”, “Goodbye”); } 11. (1.5 points) Rewrite these equations in a Postfix notation 43 - 12 * 15 / 2 18 / 14 / 2 / 10 (17 - 4) * 16 + 3 * 2 12. (1 point) Draw the Expression Tree for the following equation: 9 + 23 / 5 * ( 4 - 2 ) 5 13. (2 points) What is the Shunting Algorithm (give the main characteristics of what it can do; do not list the steps) and who invented it? 14. (1 point) How can we test non-public methods in C#? 15. (1 point) What is a lambda expression? 16. (3 points) Using delegates and lambda expressions, write code to allow any number to be transformed into another. Show two examples of use: 1) a number is transformed into its square number and 2) a number is doubled, i.e. the number is always multiplied by 2? 6 17. (2 points) What is reflection? Give two examples where reflection can be useful. 18. (1.5 points) What is XML? Compare and contrast with alternative solutions (e.g., binaries, plain text). 19. (1 point) What is the first question that you should ask yourself when thinking about the designing your application? 20. (1 point) What are the two questions you will ask yourself when wondering whether you should use an interface or an abstract class? 21. (15 points) Nespresso contacts you to implement an Point-of-Sale application that will help them sell their coffee and machines as well as help them manage the tasting of their coffee in the different Nespresso stores. They have two families of coffee machines: Vertuo and Original. The original one makes short espressos and has a larger variety of capsules – this was their first type of machine. The Vertuo makes very long espresso (the size of a mug). The capsules for the two machines are different and are not interchangeable (the original takes only one size of capsules; the Vertuo takes 3 different sizes and all three make different sizes of espresso). All 7 capsules have the following characteristics: they all have a name; an intensity (from 1 (mild) to 10 (strong) typically but seasonal varieties have even stronger intensity (e.g., 13); they can be caffeinated, decaffeinated, or half-half; a price; and a description. A couple of examples of capsules for each machine follow: Name Intensity Description Price Caffeine Machine Columbia 6 Winey and red fruits $0.72 Caffeinated Original Ristretto Decaffeinato 10 Powerful and contrasting $0.70 Decaffeinated Original Melozio 6 Smooth and balanced $1.10 Caffeinated Vertuo Half Caffeinato 5 Sweet and velvety $1.10 Half Caffeinated Vertuo The way the machine works, is that once it is ON and it has a capsule inserted, you can press the a button and the coffee starts pouring. You can wait for it to finish or you can stop it earlier to have it shorter and more intense. The Nespresso Stores sell machines and capsules, but also offer you to try coffee. You can assume that the store that will use your prototype application has 2 machines: 1 Original and 1 Vertuo. Typically, when a client arrives, an Nespresso agent will ask her/him whether she/he wants to drink a coffee and if yes what type. The agent will enter this into the system and the system should automatically run the preparation of the espresso. While the coffee is preparing the client can buy capsules/machines. Design and build a console prototype of the application. Your application should provide all features described above to the Nespresso agent, in other words: sell capsules and machines and automatically run the preparation of the espresso. Use page 8 only for explaining your design choices. Feel free to draw class diagrams, sequence diagrams, or simply enumerate the choices you are making. Use pages 9 to 11 to write the actual code. 8 Use this page to draw/talk about your design only. 9 10 11 12 DRAFT
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