6.1 a) for, while. b) after. c) switch. d) continue. e) && (conditional AND) or & (boolean logical AND). f) false. g) static.

6.2 a) False. The default label is optional. If no default action is needed, then there’s no need for a default label. b) False. You could terminate the case with other statements, such as a return. False. Both of the relational expressions must be true for this entire expression to be true when using the && operator. d) True. e) True. f) False. The switch statement does not provide a mechanism for testing ranges of values, so you must list every value to test in a separate case label. g) True.

6.3 The answers to Self-Review Exercise 6.3 are as follows:

1. 
   sum = 0;
   for (count = 1; count <= 99; count += 2)
   {
      sum += count
   }
   

2. double result = Math.Pow(2.5, 3);

3. 
   i = 1;
   
   while (i <= 20)
   {
      Console.Write(i);
   
      if (i % 5 == 0)
      {
         Console.WriteLine();
      }
      else
      {
         Console.Write('	');
      }
   
      ++i;
   }
   

4. 
   for (i = 1; i <= 20; ++i)
   {
       Console.Write(i);
   
       if (i % 5 == 0)
       {
          Console.WriteLine();
       }
       else
       {
          Console.Write('	');
       }
   }
   

6.4 The answers to Self-Review Exercise 6.4 are as follows:

1. Error: The semicolon after the while header causes an infinite loop, and there’s a missing left brace for the body of the while statement.

   Correction: Remove the semicolon and add a { before the loop’s body.

2. Error: Using a floating-point number to control a for statement may not work, because floating-point numbers are represented only approximately by most computers. Correction: Use an integer, and perform the proper calculation in order to get the values you desire:

   
   for (k = 1; k < 10; ++k)
   {
      Console.WriteLine((double) k / 10);
   }
   

3. Error: case 1 cannot fall through into case 2.

   Correction: Terminate the case in some way, such as adding a break statement at the end of the statements for the first case.

4. Error: The wrong operator is used in the while iteration-continuation condition. Correction: Use <= rather than <, or change 10 to 11.