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Questions and Exercises: Control Flow

Questions

1. Recall the WhileDemo and DoWhileDemo programs.

   public class WhileDemo {
       public static void main(String[] args) {
   
           String copyFromMe = "Copy this string until you encounter the letter 'g'.";
           StringBuffer copyToMe = new StringBuffer();
   
           int i = 0;
           char c = copyFromMe.charAt(i);
   
           while (c != 'g') {
               copyToMe.append(c);
               c = copyFromMe.charAt(++i);
           }
           System.out.println(copyToMe);
       }
   }
   

   ---

   public class DoWhileDemo {
       public static void main(String[] args) {
   
           String copyFromMe = "Copy this string until you encounter the letter 'g'.";
           StringBuffer copyToMe = new StringBuffer();
   
           int i = 0;
           char c = copyFromMe.charAt(i);
   
           do {
               copyToMe.append(c);
               c = copyFromMe.charAt(++i);
           } while (c != 'g');
           System.out.println(copyToMe);
       }
   }
   

   • What would the output be from each program if you change the value of the string copyFromMe to "golly gee. this is fun."?
   • Would the output from the two programs be the same? Defend your answer.

2. Here's the Sort program again:

   public class Sort {
       public static void main(String[] args) {
           int[] arrayOfInts = { 32, 87, 3, 589, 12, 1076,
                                 2000, 8, 622, 127 };
   
           for (int i = arrayOfInts.length; --i >= 0; ) {
               for (int j = 0; j < i; j++) {
                   if (arrayOfInts[j] > arrayOfInts[j+1]) {
                       int temp = arrayOfInts[j];
                       arrayOfInts[j] = arrayOfInts[j+1];
                       arrayOfInts[j+1] = temp;
                   }
               }
           }
   
           for (int i = 0; i < arrayOfInts.length; i++) {
               System.out.print(arrayOfInts[i] + " ");
           }
           System.out.println();
       }
   }
   

   • Identify all of the control flow statements in the program.

Check your answers.

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