Chapter 09 Worksheet

Return to worksheet index.

For the code below, write a prediction on what it will output. Then run the code and state if your prediction was accurate or not. If your prediction is incorrect, make sure you understand why.

If you don't know why the code runs the way it does, watch the video at the end of the assignment for an explanation. If you are looking at the text-only version of this worksheet, go on-line and find the HTML version of this worksheet for the video.

This section is worth 10 points, a half point per problem rounded up.

1. Block 1 (Remember, guess AND actual. You'll lose 19 points if you skip guessing the output of the next 19 problems, and completely miss the point of this part.)

   for i in range(5):
       print(i + 1)
   

2. Block 2

   for i in range(5):
       print(i)
       i = i + 1
   

3. Block 3

   x = 0
   for i in range(5):
       x += 1
   print(x)
   

4. Block 4

   x = 0
   for i in range(5):
       for j in range(5):
           x += 1
   print(x)
   

5. Block 5

   for i in range(5):
       for j in range(5):
           print(i, j)
   

6. Block 6

   for i in range(5):
       for j in range(5):
           print("*", end="")
           print()
   

7. Block 7

   for i in range(5):
       for j in range(5):
           print("*", end="")
       print()
   

8. Block 8

   for i in range(5):
       for j in range(5):
           print("*", end="")
   print()
   

9. Block 9

   # This is supposed to sum a list of numbers
   # What is the mistake here?
   my_list = [5, 8, 10, 4, 5]
   i = 0
   for i in my_list:
       i = i + my_list[i]
   print(i)
   

10. Block 10

    for i in range(5):
        x = 0
        for j in range(5):
            x += 1
    print(x)
    

11. Block 11

    import random
    play_again = "y"
    while play_again == "y":
        for i in range(5):
            print(random.randrange(2), end="")
        print()
        play_again = input("Play again? ")
    print("Bye!")
    

12. Block 12

    def f1(x):
        print(x)
    y = 3
    f1(y)
    

13. Block 13

    def f2(x):
        x = x + 1
        print(x)
    y = 3
    f2(y)
    print(y)
    

14. Block 14

    def f3(x):
        x = x + 1
        print(x)
    x = 3
    f3(x)
    print(x)
    

15. Block 15

    def f4(x):
        z = x + 1
        print(z)
    x = 3
    f4(x)
    print(z)
    

16. Block 16

    def foo(x):
        x = x + 1
        print("x=", x)
    
    x = 10
    print("x=", x)
    foo(x)
    print("x=", x)
    

17. Block 17

    def f():
        print("f start")
        g()
        h()
        print("f end")
    
    def g():
        print("g start")
        h()
        print("g end")
    
    def h():
        print("h")
    
    f()
    

18. Block 18

    def foo():
        x = 3
        print("foo has been called")
    
    x = 10
    print("x=", x)
    foo()
    print("x=", x)
    

19. Block 19 (This demonstrates a new concept that won't be fully explained until Chapter 12.)

    def a(x):
        print("a", x)
        x = x + 1
        print("a", x)
    
    x = 1
    print("main", x)
    a(x)
    print("main", x)
    
    def b(y):
        print("b", y[1])
        y[1] = y[1] + 1
        print("b", y[1])
    
    y=[123, 5]
    print("main", y[1])
    b(y)
    print("main", y[1])
    
    def c(y):
        print("c", y[1])
        y = [101, 102]
        print("c", y[1])
    
    y = [123, 5]
    print("main", y[1])
    c(y)
    print("main", y[1])
    

Correcting Code

This next section involves finding the mistakes in the code. If you can't find the mistake, check out the video at the end for the answer and an explanation on what is wrong.

This section is worth 7 points.

1. Correct the following code: (Don't let it print out the word ``None'')

   def sum(a, b, c):
       print(a + b + c)
   
   print(sum(10, 11, 12))
   

2. Correct the following code: (x should increase by one, but it doesn't.)

   def increase(x):
       return x + 1
   
   x = 10
   print("X is", x, " I will now increase x." )
   increase(x)
   print("X is now", x)
   

3. Correct the following code:

   def print_hello:
       print("Hello")
   
   print_hello()
   

4. Correct the following code:

   def count_to_ten():
       for i in range[10]:
           print(i)
   
   count_to_ten()
   

5. Correct the following code:

   def sum_list(list):
       for i in list:
           sum = i
           return sum
   
   list = [45, 2, 10, -5, 100]
   print(sum_list(list))
   

6. Correct the following code: (This almost reverses the string. What is wrong?)

   def reverse(text):
       result = ""
       text_length = len(text)
       for i in range(text_length):
           result = result + text[i * -1]
       return result
   
   text = "Programming is the coolest thing ever."
   print(reverse(text))
   

7. Correct the following code:

   def get_user_choice():
       while True:
           command = input("Command: ")
           if command = f or command = m or command = s or command = d or command = q:
               return command
   
           print("Hey, that's not a command. Here are your options:" )
           print("f - Full speed ahead")
           print("m - Moderate speed")
           print("s - Status")
           print("d - Drink")
           print("q - Quit")
   
   user_command = get_user_choice()
   print("You entered:", user_command)
   

(13 pts) For this section, write code that satisfies the following items:

1. Write a function that prints out ``Hello World.''
2. Write code that will call the function in the prior problem.
3. Write a function that prints out ``Hello Bob'', and will take a parameter to let the caller specify the name. Do not put an input statement inside the function! Use a parameter.
4. Write code that will call the function in the prior problem.
5. Write a function that will take two numbers as parameters (not as input from the user) and print their product (i.e. multiply them).
6. Write code that will call the prior function.
7. Write a function that takes in two parameters. The first parameter will be a string named phrase. The second parameter will be a number named count. Print phrase to the screen count times. (e.g., the function takes in "Hello" and 5, then prints "Hello" five times.)
8. Write code to call the previous function.
9. Write code for a function that takes in a number, and returns the square of that number. (I'm not asking for the square root, but the number squared.) Note, this function should RETURN the answer, not print it out.
10. Write code to call the function above and print the output.
11. Write a function that takes three numbers as parameters, and returns the centrifugal force. The formula for centrifugal force is:
    F=m(v^2/r)
    F is force, m is mass, r is radius, and v is angular velocity.
12. Write code to call the function above and display the result.
13. Write a function that takes a list of numbers as a parameter, and prints out each number individually using a for loop.