程序代写代做代考 python Starting Out with Python 4e (Gaddis)

Starting Out with Python 4e (Gaddis)
Chapter 8 More About Strings

TRUE/FALSE

1. You cannot use a for loop to iterate over the characters in a string.

ANS: F

2. Indexing works with both strings and lists.

ANS: T

3. In slicing, if the end index specifies a position beyond the end of the string, Python will use the length of the string instead.

ANS: T

4. Indexing of a string starts at 1 so the index of the first character is 1, the index of the second character is 2, and so forth.

ANS: F

5. The index -1 identifies the last character of a string.

ANS: T

6. The following expression is valid:
string[i] = ‘i’

ANS: F

7. The following code will display ‘yes + no’:
mystr = ‘yes’
yourstr = ‘no’
mystr += yourstr
print(mystr)

ANS: F

8. If the + operator is used on strings, it produces a string that is a combination of the two strings used as its operands.

ANS: T

9. When accessing each character in a string, such as for copying purposes, you would typically use a while loop.

ANS: F

10. If a whole paragraph is included in a single string, the split() method can be used to obtain a list of the sentences in the paragraph.

ANS: T

11. The strip() method returns a copy of the string with all the leading whitespace characters removed but does not remove trailing whitespace characters.

ANS: F

MULTIPLE CHOICE

1. What are the valid indexes for the string ‘New York’?
a.
0 through 7

b.
0 through 8

c.
-1 through -8

d.
-1 through 6

ANS: A

2. What will be displayed after the following code executes?
mystr = ‘yes’
yourstr = ‘no’
mystr += yourstr * 2
print(mystr)
a.
yes + no * 2

b.
yes + no yes + no

c.
yesnono

d.
yesnoyesno

ANS: C

3. What will be assigned to the variable s_string after the following code executes?
special = ‘1357 Country Ln.’
s_string = special[ :4]
a.
‘7’

b.
‘1357’

c.
5

d.
‘7 Country Ln.’

ANS: B

4. What will be assigned to the variable s_string after the following code executes?
special = ‘1357 Country Ln.’
s_string = special[4:]
a.
‘ Country Ln.’

b.
‘1357’

c.
‘Coun’

d.
’57 C’

ANS: A

5. What will be assigned to the variable s_string after the following code executes?
special = ‘1357 Country Ln.’
s_string = special[-3:]
a.
‘135’

b.
‘753’

c.
‘Ln.’

d.
‘y Ln’

ANS: C

6. What will be assigned to the variable some_nums after the following code executes?
special = ‘0123456789’
some_nums = special[0:10:2]
a.
‘0123456789’

b.
‘24682468’

c.
‘02468’

d.
‘02020202020202020202’

ANS: C

7. If the start index is __________ the end index, the slicing expression will return an empty string.
a.
equal to

b.
less than

c.
greater than

d.
less than or equal to

ANS: C

8. What is the return value of the string method lstrip()?
a.
the string with all whitespaces removed

b.
the string with all leading whitespaces removed

c.
the string with all leading tabs removed

d.
the string with all leading spaces removed

ANS: B

9. What is the first negative index in a string?
a.
0

b.
-1

c.
-0

d.
the size of the string minus one

ANS: B

10. What will be assigned to the string variable pattern after the following code executes?
i = 3
pattern = ‘z’ * (5 * i)
a.
‘zzzzzzzzzzzzzzz’

b.
‘zzzzz’

c.
‘z * 15′

d.
Nothing; this code is invalid

ANS: A

11. Which method would you use to determine whether a certain substring is present in a string?
a.
endswith(substring)

b.
find(substring)

c.
replace(string, substring)

d.
startswith(substring)

ANS: B

12. Which method would you use to determine whether a certain substring is the suffix of a string?
a.
endswith(substring)

b.
find(substring)

c.
replace(string, substring)

d.
startswith(substring)

ANS: A

13. What list will be referenced by the variable list_strip after the following code executes?
my_string = ’03/07/2018’
list_strip = my_string.split(‘/’)
a.
[‘3’, ‘7’, ‘2018’]

b.
[’03’, ’07’, ‘2018’]

c.
[‘3’, ‘/’, ‘7’, ‘/’, ‘2018’]

d.
[’03’, ‘/’, ’07’, ‘/’, ‘2018’]

ANS: B

14. What will be the value of the variable string after the following code executes?
string = ‘abcd’
string.upper()
a.
‘abcd’

b.
‘ABCD’

c.
‘Abcd’

d.
Nothing; this code is invalid

ANS: B

15. What will be the value of the variable string after the following code executes?
string = ‘Hello’
string += ‘ world!’
a.
‘Hello’

b.
‘ world!’

c.
‘Hello world!’

d.
Nothing; this code is invalid

ANS: C

16. What will display after the following code executes?
password = ‘ILOVEPYTHON’
if password.isalpha():
print(‘Invalid, must contain one number.’)
elif password.isdigit():
print(‘Invalid, must have one non-numeric character.’)
elif password.isupper():
print(‘Invalid, cannot be all uppercase characters.’)
else:
print(‘Your password is secure!’)
a.
Invalid, must contain one number.

b.
Invalid, must have one non-numeric character.

c.
Invalid, must contain one number.
Invalid, cannot be all uppercase characters.

d.
Your password is secure!

ANS: A

COMPLETION

1. Each character in a string has a(n) __________ which specifies its position in the string.

ANS: index

2. A(n) __________ exception will occur if you try to use an index that is out of range for a particular string.

ANS: IndexError

3. The isalpha() method returns __________ if the string contains only alphabetic characters and is at least one character in length.

ANS: True

4. A(n) __________ is a span of characters that are taken from within a string.

ANS: slice

5. When the operand on the left side of the * symbol is a string and the operand on the right side is an integer, the * becomes the ___________ operator.

ANS: repetition

6. The third number in string slicing brackets represents the ___________ value.

ANS: step

7. The __________ operator can be used to determine whether one string is contained in another string.

ANS: in

8. The __________ method returns True if the string contains only numeric digits.

ANS: isdigit()

9. The __________ method returns the list of the words in a string.

ANS: split()

10. The __________ method returns a copy of the string with all the alphabetic letters converted to lower case.

ANS: lower()