581325-0 Introduction to Programming, course examination 14.11.2003/AW

1. Answer the following questions briefly and exactly:
   • When is a variable inside a method born? When does it disappear?
   • When is an object born? When does it disappear?

                                                               (10 points)
   

2. A certain granary comprises of two grain silos. Only the first silo has a loading platform. Grain can be moved from one silo to another.

   Create class Granary to implement the functionality of the granary described above.

   (The constructor and accessors interpret negative parameter values as zero)

   • public Granary(double firstSilo, double secondSilo) creates a granary with silo capacities given as parameters. The silos are empty at the beginning.

   • public double firstCap() returns the amount of grain in the first silo
   • public double secondCap() returns the amount of grain in the second silo

   • public boolean moveGrain(double amount, boolean fromFirst) moves the amount of grain declared in the double parameter from one silo to another. If the boolean parameter is true, the grain is moved from the first silo to the second, otherwise from second to first. If the whole amount doesn't fit the target silo, then nothing is moved. Returns true if the grain was moved, otherwise returns false.

   • public boolean addGrain(double amount) adds grain to the first silo. If the whole amount doesn't fit the silo, then nothing will be added. If the addition succeeded, true is returned, otherwise false.
   • public double takeGrain(double amount) takes grain from the first silo. If the silo doesn't contain enough grain, then takes all available grain. Returns the amount of grain taken.

   • public void rodentUprising(double severity) decrements the contents of both silos by the parameter percentage.

   • public String toString() returns a clear String representing the granary's state.

   Don't implement the silos as TinyStore-objects!

                                                               (14 points)
   

3. "What in the world are those method things?" , your friend wails when hearing your stories of the course Introduction to Programming. Your friend has programmed enough to know simple variables, expressions and statements. "What the heck are 'parameters', who is 'calling' and whom, why?, he goes on in despair. Help your friend understand what it is all about. Draw up a written description (1 exam paper at the most). Keep in mind that examples aid learning. In the evaluation of your answer, we will take into account the intended reader of the description, so do not write for the examinator, who already knows about it, but for that friend!

                                                               (12 points)
   

4. Implement the following guessing game as an interactive program. Before the game starts the game leader inputs 100 integers into the program in random order. Then the player starts to use the program. The player tries to guess the numebers that the game leader has input in the computer. The game ends, when the player has guessed three different numbers. The result is the number of guesses, so it is at least three.

   You may assume that the game leader really inputs 100 different numbers. For the sake of efficiency, the search for guessed numbers must be programmed with the Binary Search

                                                               (14 points)