Exam 1

Basic Programs --
Chapters 1 through 4

CS 1510
Introduction to Computing

Tuesday, October 7, 2014 @ 12:45 PM

Instructions

• The exam consists of ten (10) questions. Be sure that you have all ten and that they are all legible.


• Read all questions and their instructions thoroughly before you begin. It is worth your time to plan ahead!


• You have also been given three blank pages. Use these sheets for your exam answers. Be sure to write your name on each sheet.


• The exam is worth sixty (60) points. Each question is worth six points.


• Points will be awarded based on your explicit answers. Partial credit will be given where possible, so show all of your work.


• Whenever you are asked to answer or describe "briefly", a one-sentence response should be enough to express the solution.


• Whenever you are asked to "# fill in the blank", you need only write the new code. You do not have to copy the other code from the problem.


• The exam lasts sixty (60) minutes. It is due at 1:45 PM.

Problems

1. Write numeric expressions in Python for these value:

   1.      4 + 3 * 2n-2
           ------------
                10     
      

   2. the sum of the cubes of integers x and y
   3. the number of seconds in 4 hours, 14 minutes, and 32 seconds
      (There are sixty seconds in a minute, and sixty minutes in an hour.)


2. Write boolean expressions in Python for these conditions:
   1. x is a factor of y (that is, x divides evenly into y)
   2. age is at least 18 and state equals 'Iowa'
   3. the string name contains a 'z'


3. Consider this code:

       if x % 2 == 1:
           if x**3 != 27:
               x = x + 4
           else:
               x = x / 1.5
       else:
           if x <= 10:
               x = x * 2
           else:
               x = x - 2
       print(x)
   

   What does this code print if x == 8?



4. The user enters the birthdays of, a and b, two people who were born on different days in the same year. Write Python code that prints a is younger if a's birthday comes before b's, and b is younger if b's birthday comes before a's.

       a_month = int( input('Enter the month: ') )
       a_day   = int( input('Enter the day  : ') )
       b_month = int( input('Enter the month: ') )
       b_day   = int( input('Enter the day  : ') )
   
       # fill in the blank
   



5. Answer briefly each of these questions about algorithms and programs:
   1. In what ways is an algorithm similar to a program?
   2. In what ways is an algorithm different from a program?


6. Consider this code:

       x = input('Enter a string: ')
       y = 0
       for i in x:
           print(y, i)
           y += 1
   

   What does this code print if the user enters 'Felix'?



7. Write a Python loop to print the sum of all the odd numbers between 1 to n, for a given value of n. For example, the sum of the odds between 1 and 7 is 1 + 3 + 5 + 7 = 16.


8. Consider this code:

       x = input('Enter a string: ')
       y = 0
       for i in x:
           if i == 'a':
               y += 1
       print(y)
   

   Write a while loop that does exactly the same thing as the for loop.



9. Answer briefly each of these questions about loops:
   1. What does the break statement do in a loop?
   2. What is a loop and a half?
   3. What must the body of a while loop do that the body of a for loop does not need to do?


10. Suppose we want to censor a string in this way:

        Enter the source     : eugene
        Enter char to replace: e
        Enter char to insert : *
    
        Result: *ug*n*
    

    Write Python code that prints out the characters in string str, only with character old_ch replaced with character new_ch.

        str    = input('Enter the source     : ')
        old_ch = input('Enter char to replace: ')
        new_ch = input('Enter char to insert : ')
    
        # fill in the blank
    
        print('\nResult:', result)