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 ("*");
     
             System.out.println();
         }
    
    Modify the program to print the "upside down" triangle in part (a) of Programming Project 5.10 on page 280 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.