Test 2: Questions

X2.1.

[8 pts] What is the output of the following program?

a = '0'

for i in range(4):

    a = a + 'i'

    print(a)

X2.2.

[9 pts] For three string methods other than split, give a meaningful example of how to invoke that method and what that method returns. For example, for split, you could write, “If s is ‘hello world’ then s.split() returns the list [‘hello’, ‘world’].”

X2.3.

[15 pts] Write a program that reads integers typed by the user until the sum of the numbers typed exceeds 100; the program should then display the sum. For example, if the user enters 30 repeatedly, the program should read four of these 30’s and then display 120.

X2.4.

[6 pts] Write a regular expression that describes only those strings of a’s and b’s with exactly three a’s. Examples include aaa, ababa, and baabab, but not acaba or aabbaa.

X2.5.

[10 pts] Tabulate the values taken on by the variables i, j, and k as the below program executes.

word = 'aha'

k = 0

for i in word:

    for j in word:

        if i == j:

            k = k + 1

print(k)

X2.6.

[8 pts] What value for template would result in the following strings being produced? (Don’t include the quotes.)

`template.format(98, 24.5)`	→	“`98/4 = 24.50`”
`template.format(7, 1.75)`	→	“ `7/4 = 1.75`”

X2.7.

[6 pts] When executed, the below program results in the error “name ‘re’ is not defined.” What line must you add to repair this problem, and where should it be inserted into the program?

line = input()

words = re.findall('[a-z]+', line)

print(len(words))

X2.8.

[8 pts] Complete the while statement below so that the loop continues until a and b are both odd integers. (Recall that you can test whether a is odd by checking whether a % 2 is 1.)

a = 0

b = 0

while

    a = b

    b = int(input())

X2.9.

[10 pts] What belongs in the gap in the below program so that the program terminates the loop when the user types a number that is within 10 of goal? For example, if goal is 64, the program should terminate if the user types anything between 54 and 74.

goal = random.randrange(1, 101)

while True:

    user = int(input())







    print('more than 10 away')

print('close enough')

Test 2: Solutions

X2.1.

0i
0ii
0iii
0iiii

X2.2.

If s is “MacDonald”, s.count('a') returns 2 (the number of times a appears in s).
If s is “i is {0}”, s.format(34) returns “i is 34”.
If s is “and”, s.join(['x', 'y', 'z']) returns “xandyandz”.
If s is “MacDonald”, s.lower() returns “macdonald”.
If s is “ Old MacDonald ”, s.strip() returns “Old MacDonald” (with spaces on both ends removed).
If s is “MacDonald”, s.upper() returns “MACDONALD”.

X2.3.

One solution:	Another solution:
`total = 0 while total <= 100: num = int(input()) total = total + num print(total)`	`total = 0 while True: num = int(input()) total = total + num if total > 100: print(total) break`

X2.4.

b*ab*ab*ab*

X2.5.

i: a h a

j: a h a a h a a h a

k: 0 1 2 3 4 5

X2.6.

“{0:2d}/4 = {1:5.2f}”

X2.7.

Insert the line “import re” at the program’s beginning.

X2.8.

while a % 2 != 1 or b % 2 != 1:

X2.9.

One solution:	Another solution:
`if abs(user - goal) >= 10: break`	`if user >= goal - 10 and user <= goal + 10: break`