final10CS08_key - PIC 10C Final Exam Key Spring 2008 Prof....

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PIC 10C Final Exam Key Spring 2008 Prof. Todd Wittman 1.) [2 points] In C#, what does the reserved word override do? When is it used? A virtual function in the base class should have a corresponding override function in the derived class. The word override tells the compiler to use the derived version of the function rather than the version in the base class. 2.) [2 points] What does the BackgroundWorker control do? A BackgroundWorker allows a block of code to run asynchronously with the main UI thread. This allows time-consuming processes to run in the background without freezing up the GUI. 3.) [2 points] What does it mean to make graphics persistent ? Describe briefly our procedure for making C# graphics persistent. Persistent graphics stay on the screen after the screen is repainted, like when a window covers up the GUI. We made our graphics persistent by drawing all graphics to a Bitmap canvas and displaying the Bitmap every time the Paint event is fired. 4.) [4 points] Suppose in C++ we have a base class B and a derived class D . Suppose b and d are objects of classes B and D, respectively. B b; D d; Explain what happens in each situation below. a.) b = d; This runs, but any extra data fields in d are sliced away. b.) d = b; This gives a compile error. 5.) [5 points] Student records at Springfield University are stored in a class Student. The registrar wants to be able to quickly look up a student record based on either the student's name or ID number. Write a block of C++ code that sets up a multi-key hash table that allows O(1) look-up of a record by name or ID. To illustrate how records are inserted into the hash table, create a record for Lisa Simpson (major="English", ID=42) and insert it into the hash table. list<Student> L;
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This note was uploaded on 05/18/2010 for the course PIC 10C taught by Professor Wittman during the Spring '10 term at UCLA.

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final10CS08_key - PIC 10C Final Exam Key Spring 2008 Prof....

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