/*		CSC 15 Final Exam Study Guide : Sample solutions

  Exam format will be similar to the midterm and quizzes.

  The exam will be "naturally" cummulative, with emphasis on

  loops, including nested loops
  arrays
  strings
  functions, including functions on arrays
  class and objects

  You should study the material on the midterm exam as well.  You'll have
to implement a class like on the midterm, except I won't be writing out
half of it for you - I will provide more general descriptions of what the
class should be.

  What will not be covered:

  graphical user interfaces
  I/O (except System.out.println)

  HOWEVER, IT WILL COVER THE USE OF EXCEPTIONS


 Additional Practice Problems (sample solution availabe at review session)
*/

class funs
{
    //  1. Write a function that takes an array of integers as a parameter
    //     and print the contents of the array backwards.

    public void backwards(int[] A)
    {
	int i=A.length-1;
        while (i>=0)
	    {
		System.out.print(A[i]);
		i--;
	    }
    } // backwards

/*  2. Write a function that determines if a string S contains a given
     character:

     public boolean instring(String s, char a)

     For example, instring("abc",'b') should return true and 
     instring("abc",'d') should return false.
*/
     
    public boolean instring(String s, char a)
    {
	boolean answer = false; // there exists relation
	int i=0;
	while (i<s.length()  && answer==false)
	    {
		if (s.charAt(i)==a) answer = true;
	    }
	return answer;
    } // instring

/*
 3. Write a program that prints out all the powers of two up to
     2 to the 30th power (1gig):

     1 2 4 8 16 32 64 128 ...

     In addition to printing them, store them in an array of 31 elements
     That is, the nth element of the array should hold 2 to the nth power.

     Note that you can use either (int)Math.pow to compute the power, or
     use an inner loop.
*/

    public int[] powers() // return value is array to store results in
    {
	int[] P;
	P = new int[31];
	int ax = 1; // accumulator
	int i = 0;  int j = 0;
	while (i<P.length)
	    {
		ax = 1;
		for(j=0;j<i;j++) 
		    { ax = 2*ax; }
		P[i] = ax;
		System.out.println(ax);
		i++;
	    }
	return P;
    } // powers

/*
  4. Write a program that prints out the multiplication table:

1  2  3  4  5  6  7  8  9
2  4  6  8  10 12 14 16 18
3  6  9  12 ...
4  ...
5
6
7
8
9
*/

    public void multtable()
    {
	int i, j;
	for (i=1;i<10;i++)
	    {
		for(j=1;j<10;j++)
		    {
			System.out.print(i*j + "\t"); // \t is tab
		    } // inner loop
		System.out.print("\n");
	    } // outer loop
    } // multtable

} // class funs



/*
5. You work at a video store and you want to write a program that keeps 
track of movies your customers rent.  Write a class to represent individual
movies.  It should contain the following data:

  title of movie (string)
  whether the movie is a new release or older movie (boolean)
  name of customer who rented the movie (string, with "nobody" meaning
   the movie's not been rented).
  

  Methods:
  
  Constructor : initialize title and newrelease, and set customer to "nobody"


  accessors:  methods that return the title of the movie and whether the
    movie is a new or older release.

  A meothd "available" that determines if the movie is in store or rented.

  A method "checkout" that represents renting a movie to a customer.  If
  The movie's already checkout out, it should throw an exception.

  A method "returnmovie" that represents a movie being returned.

  A method to change the status of newrelase from true to false.


Now, in main or somewhere else, create an array of at least 4 movie
objects and call each of the methods you've written.
*/

public class movie
{
    private String title;
    private boolean newrelease;
    private String customer;
    
    public movie(String t, boolean n)
	{
	    title = t; newrelease = n;
	    customer = "nobody";
	}

    public String title() { return title; }
    public boolean newrelease() { return newrelease; }

    public boolean available()
	{
	    if (customer.equals("nobody")) return true;
	    else return false;
	}

    public void checkout(String c) throws Exception
        {  
	    if (customer.equals("nobody"))
		customer = c; 
	    else throw new Exception("already rented");
	}
    
    public void returnmovie() 
	{
	    customer = "nobody";
	}
    

    public void changestatus(boolean newstatus)
    { newrelease = newstatus; }

    public static void main(String[] args)
    {
	// make an array of movies:
	movie[] M = new movie[3];
	M[0] = new movie("citizen kane",false);
	M[1] = new movie("lord of the rings",true);
	M[2] = new movie("kill bill",true);
	try  // needed because code could throw exception
	    {
		M[0].checkout("fred");
		M[1].changestatus(false);
		M[0].returnmovie();
		System.out.println(M[2].available());
	    }
	catch (Exception e) 
	    { System.out.println(e); System.exit(1); }

    } // main
} // class movie