quiz.md

CSE 142

Quiz

Week 4

1. Expressions, 10 points. For each expression in the left-hand column, indicate its value in the right-hand column. Be sure to list a constant of appropriate type (e.g., 7.0 rather than 7 for a double, Strings in quotes).

   Expression	Value
   12 / 3 + 5 + 3 * -2
   1 + 1 + "(1 + 1)" + 1 + 1
   13 / 2 - 38 / 5 / 2.0 + (15 / 10.0)
   11 < 3 + 4 || !(5 / 2 == 2)
   20 % 6 + 6 % 20 + 6 % 6

2. Parameter Mystery, 12 points. Consider the following program.

   public class ParameterMystery {
       public static void main(String[] args) {
           int a = 5;
           int b = 1;
           int c = 3;
           int three = a;
           int one = b + 1;
   
           axiom(a, b, c);
           axiom(c, three, 10);
           axiom(b + c, one + three, a + one);
           a++;
           b = 0;
           axiom(three, 2, one);
       }
   
       public static void axiom(int c, int b, int a) {
           System.out.println(a + " + " + c + " = " + b);
       }
   }

   List below the output produced by this program.

3. If/Else Simulation, 12 points. Consider the following method.

   public static void ifElseMystery(int a, int b) {
     if (a % 10 == 0) {
         b = b * 10;
         a = a + 10;
     }   
     if (a > b) {
         b = a;
     } else if (a == b) {
         b++;
     }
     System.out.println(a + " " + b);
   }

   For each call below, indicate what output is produced.

   Method Call	Output
   ifElseMystery(20, 8);
   ifElseMystery(30, 30);
   ifElseMystery(4, 3);
   ifElseMystery(3, 4);
   ifElseMystery(30, 4);
   ifElseMystery(7, 7);

4. While Loop Simulation, 12 points. Consider the following method:

   public static void whileMystery(int i, int j) {
       int k = 0;
       while (i < j && k < j) {
           i = i + k;
           j--;
           k++;
           System.out.print(i + ", ");
       }
   
       System.out.println(k);
   }

   Write the output of each of the following calls.

   Method Call	Output
   whileMystery(3, 5);
   whileMystery(5, 3);
   whileMystery(-3, 6);
   whileMystery(2, 12);

5. Assertions, 15 points. You will identify various assertions as being either always true, never true or sometimes true/sometimes false at various points in program execution. The comments in the method below indicate the points of interest.

   public static int mystery(int x) {
       if (x <= 0) {
           x = 42;
       }
       int y = 0;
       // Point A
       while (x != 1) {
           // Point B
           if (x % 2 == 0) {
               y++;
               x = x / 2;
               // Point C
           } else {
               x = 3 * x + 1;
               // Point D
           }
       }
       // Point E
       return y;
   }

   Fill in the table below with the words always(A), never(N) or sometimes(S).

   	x == 1	x % 2 == 1	y == 0
   Point A
   Point B
   Point C
   Point D
   Point E