PreLab 9: More Loops

  1. Trace the execution of the following loop by showing the value of each variable at each iteration in the table next to the code.
          final int LIMIT = 15;                num          sum       
          int num = 1;                         ---          ---  
          int sum = 0; 
          while (num < LIMIT)
             num = num + 3;
             sum = sum + num;
          System.out.println ("Last number is " +  num + " and sum is " + sum);
  2. What is printed by the above code?




  3. Write a for loop equivalent to the while loop above.







  4. Complete the following code to print the string read in backwards. Use a for loop.
          String str;
          int length;
          System.out.print ("Enter a string of characters: ");
          str = scan.nextLine();
          // Find the length of str
          // Write a for loop to print the string backwards
  5. The following nested loop prints a triangle of stars (see page 250 of your text - it shows the whole program and the output).
          final int MAX_ROWS = 10;
          for (int row = 1; row <= MAX_ROWS; row++)
             for (int star = 1; star <= row;  star++)
                System.out.print ("*");
    Modify the code to print the "upside down" triangle in part (a) of Programming Project 5.10 on page 286 of the textbook.




  6. Write a fragment of code that reads in a sequence of numbers and finds the smallest number read in. Use a do ... while loop. Control the loop by asking the user if there are more numbers to enter. Read the answer into a String variable. You may assume the numbers will be in the range -1000 to +1000.