CS 151, fall 2019
Exam 2

Grading - unless stated otherwise each part is worth 1 point.  There are a total of __ points.

Please fill in the following.

0) Name:



1) Python keywords (8 points, 1/2 point each, around 16 on the exam)
For this section answer with the appropriate python keyword

1.1) Data type for True and False:

1.2) Loop with only condition:

1.3) Test if something is inside of a list/string/tuple/dictionary:

1.4) Function to write to the screen:

1.5) Function to convert a string to an integer:

1.6) Boolean values (two keywords):

1.7) Conditional statements (three keywords):

1.8) Boolean operator, True only if both sides are True:

1.9) To load a module:

1.10) Special value for a variable that has no value: 

1.11) Exit the current loop:

1.12) Remove from a list by position:

1.13) Loop that iterates through a list:

1.14) Keyword to send a value back from a function:

1.15) Declare a function:

1.16) Go back to top of the loop (end the current iteration):

1.17) Function to generate a sequence of numbers:

1.18) Function to get the length of a string:

1.19) For using variable from main program inside a function:

1.20) End the current loop:

1.21) Exception handline (5 keywords):

1.22) Determine whether two objects are the same object(not just value):

1.23) Text data type:

1.24) Boolean operator, True if either side is True:

1.25) Boolean operator, negates: 





2) Evaluate the Python expression (8 points, 1/2 point each, around 16 on the exam)
Assume the following initialization code has just run.  Write exactly what Python would print as the result of each expression.
line = 'Hello, my name is HAL.'
L = line.split(' ')
color = 'orange'
pi = 3.14
prime = 7
d = {'num': pi, 'list': L, 'tuple': (0, 1, 2)}

def total(var):
  t = 0
  for x in var: 
    t = t + x
  return x

def cat(var):
  s = ''
  for x in var:
    s = s + str(x)
  return s


2.1) 'N' in color

2.2) cat(d['tuple'])

2.3) 3 <= 3

2.4) prime == 'prime'

2.5) 'n' in color

2.6) int('7') + int('6')

2.7) color * 3

2.8) prime // 2

2.9) not False

2.10) 3 < 3

2.11) line[0]

2.12) 4 + 2 * 3

2.13) '0' in d['tuple']

2.14) len(color)

2.15) 7 + 6

2.16) prime % 2

2.17) pi == 3.1

2.18) str(7) + str(6)

2.19) False or True

2.20) len('hi there')

2.21) '7' + '6'

2.22) cat('hello')

2.23) 4 * 2 + 3

2.24) 3 == 3

2.25) total(range(0, 4))

2.26) True and False

2.27) L[0]

2.28) 'int("7")' + 'int("6")'

2.29) d['tuple'][1]

2.30) 3 != 3

2.31) prime ** 2

2.32) len(L)

2.33) len([1, 2, 4])





3) Short Python (1.5 points each, around 8 points total on the exam)
Assume the initialization code from problem 2 has just been run.  For each of the following, give the python code to complete the task.

3.1) set pi to be itself divided by 2: 

3.2) print keys in d variable: 

3.3) print first item in L variable: 

3.4) print total of 10+11+12+...+20: 

3.5) add pi and prime variables, save into variable named y: 

3.6) print each letter in line variable on a separate line: 

3.7) print first 3 characters in color variable: 





4) Python functions (8 points total on the exam, 2-3 problems)
Create a python function to do each of the following.  Note - on the test there will be two.
4.1) Parameters are a list and an integer n, print first items in the list

4.2) Parameter is a dictionary, changes all values to be None (leave keys as they are)

4.3) Parameter is a list of numbers, returns the minimum

4.4) Parameter is a filename - open, read and print the file



5) Play computer (8 points total on the exam, 2-3 problems)

5.1) Selection Sort

def selection_sort(arr):

    for i in range(len(arr)):
        # index of the minimum index
        minx = i

        for j in range(i+1, len(arr)):
            if arr[j] < arr[minx]:
                minx = j

        # Swap values
        tmp = arr[minx]
        arr[minx] = arr[i]
        arr[i] = tmp

L = [7, 3, 9, 2]
selection_sort(L)

For each value of i, write what L is at the end of the loop inside selection_sort


i=0


i=1


i=2


i=3


5.2) Play Computer

def countdown(i):
  print(i)
  if i > 0:
    countdown(i//2)
  else:
    return i

L = [3, 1, 8]

L[0] = countdown(L[0])
L[2] = countdown(L[2])


L:   


i: 


screen: