CPSC 120 Pre-Lab Assignment: Lab #2

1. Trace the execution of the following program and show the output (write it as close to the way the computer would as possible even if you think it is wrong!):

   //****************************************************
   // Silly program
   //****************************************************
   
   public class Silly
   {
      //-----------------------------------------
      // The main method prints some things.
      //-----------------------------------------
      public static void main (String[] args)
      {
         int sideLength = 5;
         int area = sideLength * sideLength;
         int perimeter = 4 * sideLength;
   
         System.out.println ("A square with side of length " + sideLength
              + " has area " + area);
         System.out.println ("The perimeter is " + perimeter);
   
         sideLength = sideLength + 7;
         area = sideLength * sideLength;
         System.out.println ("A square with side of length " + sideLength
              + " has area " + area);
         System.out.println ("The perimeter is " + perimeter);
       }
   }
   
    
   OUTPUT:
   
   
   
   
   
   
   
   
   

2. Write Java code to do each of the following:
   1. Set up storage for (that is, declare) an integer variable count without giving it an initial value.

      
      

   2. Set up storage for an integer variable count and give it an initial value of 0.

      
      

   3. Set count to 5, assuming that it has already been declared as an integer variable.

      
      

   4. Set count to one more than its current value, assuming that it has already been declared as an integer variable and currently has a value.

   
   

3. The following program reads three integers and prints the average. Fill in the blanks so that it will work correctly.

   // ********************************************************************
   // FILE: Average.java
   // Purpose: Read three integers from the user and print their average
   // ********************************************************************
   
   import __________________________________________;
   
   public class Average
   {
     public static void main(String[] args)
     {
       int val1, val2, val3;
       double average;
   
       // Create a Scanner object named scan
   
       __________________________________________________  ;
   
       // get three values from user
       System.out.println("Please enter three integers and " +
                          "I will compute their average");
   
       __________________________________________________  ;
   
       __________________________________________________  ;
   
       __________________________________________________  ;
   
       //compute the average and store in the variable average
   
       __________________________________________________  ;
   
       //print the average with appropriate label (not just the number!)
   
       ______________________________________________________ ;
     }
   }
   

   
   
4. What is the difference between a variable and a constant?

   
   
   
   

5. Given the declarations below, find the result of each expression.

   int a = 3, b = 10, c = 7;
   double w = 12.9, y = 3.2;
   
   a + b * c
   
    
   a - b - c
   
    
   a / b
   
    
   b / a
   
    
   a - b / c
   
    
   w / y
   
    
   y / w
   
    
   a + w / b
   
    
   a % b / y
   
    
   b % a
   
    
   w %  y
   
    
    (double) a / b
   
    
   b / 100
   
    
   b / 100.