LoopTest.java Questions

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Program listing

 
// LoopTest.java
// Copyright (C) 1998-2016 Davin Pearson
// Website: http://davin.50webs.com/java-tutorials

class LoopTest {
   // The main method is the point of entry into the program...
   public static void main(String[] args)
   {
      LoopTest me = new LoopTest();
      me.doStuff();
   }
   // add your code here...
   public void doStuff()
   {

   }
   // These functions compute powers of two.
   public int powerOf2A(int n)
   {
      int counter = n;
      int result  = 1;
      while (counter != 0)
      {
         result = 2 * result;
         counter--;
      }
      return result;
   }
   public int powerOf2B(int n)
   {
      int counter = n;
      int result  = 1;
      do
      {
         result = 2 * result;
         counter--;
      } while (counter != 0);
      return result;
   }
   public int powerOf2C(int n)
   {
      int counter;
      int result;
      for (counter = n, result = 1; counter != 0; counter--)
      {
         result = 2 * result;
      }
      return result;
   }
   /**
     *  Prints a row of stars of a given length.
     */
   public void printLineC(int length)
   {
      for (int i=0; i<length; i++)
      {
         System.out.print("#");
      }
      System.out.println();
   }
}

// QUESTIONS:
//
// (1) In the doStuff method, some lines of code to test out
// the methods powerOf2A, powerOf2B and powerOf2C.
// 
// (2) There is a bug in the powerOf2B method because it
// does not behave correctly in the case when n is zero.
// Put an "if" statement at the top of this method to make
// it handle the case of zero properly.
// 
// (3) By copying the pattern of powerOf2A, powerOf2B and
// powerOf2C, write methods printLineA and printLineB that
// work identically to the method printLineC, except that
// they use "while" loops and "do" loops.  Add some code to
// the doStuff method to test them out.
// 
// (4) Based on the previous three questions, is there a best
// looping construct?  Or does it depend on what the looping
// construct is going to be used for?
//