Quiz 3 Material

Question 1

if vs. elif vs. else

Answer 1

• if is the first and main expression
• elif is optional and it is another conditional that python checks for (you can have as many as you want)
• else is also optional, if none of the above expressions are true, then these statements run

Question 2

= vs. ==

Answer 2

= assignment
== checking equality

Question 3

does order matter for strings and is repetition ok?

Answer 3

yes and yes

Question 4

does string indexing start at 0 or 1

Answer 4

0

Question 5

write an expression that would give the length of this string, a positive index for l, and a negative index for l:

s = ‘wilson’

Answer 5

len(s)
s[2]
s[-4]

Question 6

indexing is how to get ___ thing out of a collection
slicing is how to get _____ out of a collection

Answer 6

one
a chunk

Question 7

what are the different variations of the slicing expression?

Answer 7

s[start:end]
s[start:]
s[:end]
s[start:end:step]

Question 8

do we include or exclude the end index?

Answer 8

exclude

Question 9

how are for loops formatted?

Answer 9

for <variable> in <collection>:
statements</collection></variable>

Question 10

which numbers are include in range(8)

Answer 10

0,1,2,3,4,5,6,7

Question 11

in a range, is the stop exclusive or inclusive? what about the start?

Answer 11

stop: exclusive
start: inclusive

Question 12

what if the start is greater than the stop?

Answer 12

nothing will print, unless the step is a negative integer

Question 13

accumulator pattern

Answer 13

• idea: loop through some collection and “accumulate” some stuff
• start with nothing (initialize the accumulator variable)

Question 14

+= -= *= /= %= **= //=

Answer 14

augmented assignment operators
variable = variable + 1
variable = variable - 1

Question 15

how are while loops formatted?

Answer 15

while boolean_expression:
statement(s)

keeps doing the action over and over so long as the boolean expression is true

Question 16

do you have to change some aspect of the guard condition in the body of the while loop?

Answer 16

yes, so it will eventually by false

Question 17

we use the word “bug” to refer to….
any ____ in your code
anything your code did that didn’t match _____ __________

Answer 17

error
your intention

Question 18

syntax error

Answer 18

code violates the rules of the programming language, and thus cannot be run

Question 19

runtime error

Answer 19

code runs, but enters an illegal states or tires to do something impossible

Question 20

logical error

Answer 20

this cause your program to operate incorrectly, but not crash
syntax is correct, the code doesn’t crash, but the output is incorrect

Question 21

are list mutable?
what would this do:
my_list = [1, 2, 3, 4, 5]
my_list[2:4] = [98, 99, 100]
print(my_list)

Answer 21

yes
my_list = [1, 2, 98, 99, 100, 3, 4, 5]
if it is just one that you are adding, it can be an integer
if it is more than one, it has to be a list

Question 22

what would this do:
my_list = [1, 2, 3, 4, 5]

my_list.insert(2, 77)

Answer 22

[1, 2, 77, 3, 4, 5]

Question 23

what would this do:
my_list = [1, 2, 3, 4, 5]

my_list.append(100)

Answer 23

[1, 2, 3, 4, 5, 100]
if a list is appended, there will be a list inside of a list

Question 24

what would this do:
my_list = [1, 2, 3, 4, 5]

my_list.extend([81, 82, 83])

Answer 24

[1, 2, 3, 4, 5, 81, 82, 83]
it has to be a list

Question 25

what will each of these do? numbers.remove(4) numbers.pop(3) numbers.pop() del numbers[2]

Answer 25

if 4 is in the list, it will remove 4 (if not there is an error) removes and returns the value at index 3 removes and returns the last value deletes the value at index 2

Question 26

what will each of these do? numbers * 3 number + [3] numbers + numbers

Answer 26

take a list and turn it into the list copied three times put into one big list add 3 to the end of the list turns the list into a big list with 2 copies of the original list

Question 27

what will each of these do? numbers.index(6) numbers.count(6) numbers.sort() numbers.reverse()

Answer 27

give the index that the value 6 is in the list (error if not in the list) give the number of times that 6 is in the list (0 if not in the list) sort from smallest to largest reverses the order of the list

Question 28

aliasing

Answer 28

making a value known by two different names and can be changed by either one

Question 29

for a list passed to functions, modifying the parameter will __________ change the value outside of the function

Answer 29

permanently

Question 30

are tuples mutable?

Answer 30

no

Question 31

in a nested loop, the inner loop must finish _____ (before/after) outer loop increments once

Answer 31

before