Final Exam Prep Flashcards
Which mode specifier will open a file but will not let you change the file or write to it?
read
Which mode specifier will erase the contents of a file if it already exists and create it if it does not exist?
write
Assume that there is a variable named customer that references a file object. How would you write the string ‘Mary Smith’ to the file?
customer.write(‘Mary Smith’)
If a file has been opened properly, which method will return the file’s entire contents as a string?
read()
Which method could be used to strip specific characters from just the end of a string?
rstrip()
Given that the file is valid and contains numbers, what does x contain after the following statement?
x = open(“numbers.txt”, “r”)
a file object
Which of these is not a valid file mode when opening a file in Python?
f
Before a file can be used by a program, it must be _________.
opened
This is a single piece of data within a record.
field
When a file is opened in this mode, data will be written at the end of the file’s existing contents.
append mode
To respond to errors, what kind of a statement must be used?
try/except
Which of these causes an IOError?
Opening a file that doesn’t exist.
Which of these is associated with a specific file, and provides a way for the program to work with that file?
File object
What do you call the process of retrieving data from a file?
Reading
A(n)__________ is a function that belongs to an object, and performs some operation using that object.
method
A(n) ______ is a complete set of data about an item.
record
The ________________ is one or more statements grouped together with the anticipation that they could potentially raise an exception.
try block
When opening a file in write mode, if a file with the specified name already exists, a warning message is generated. T/F
False
Closing a file disconnects the communication between the file and the program. T/F
True
In Python, there is no way to prevent a program from crashing if it attempts to read a file that does not exist. T/F
False
Strings can be written directly to a file with the write method, but numbers must always be converted to strings before they can be written to a file. T/F
True
The while loop automatically reads a line in a file without testing for any special condition that signals the end of the file. T/F
False
A file can safely be opened and closed multiple times within the same program. T/F
True
Given a valid file that contains multiple lines of data, what is the output of the following code:
f=open(“names.txt”,”w”)
print(f)
None of these
The contents of the entire file are printed
The letter “f” is printed.
Only the first line of the file is printed
Given a valid file containing multiple lines of data, what does the print() statement print out the first time that it is called:
f=open(“data.txt”,”r”)
for line in f:
line=f.readline()
print(line)
The second line of the file
The following code could potentially raise an IOError. T/F
f=open(“names.txt”, ‘r’)
for x in f:
print(5/x.rstrip())
False
The following code could potentially raise a ZeroDivisionError. T/F
f=open(“names.txt”, ‘r’)
for x in f:
print(5/x.rstrip())
True
When a file is first open successfully, where is the read position indicator?
At the beginning of the file
What is needed to delete a single line from a file?
The creation of a new file
This is a small “holding section” in memory that many systems write data to before writing the data to a file.
Buffer
What is the output of the following code?
number = [0,1,2,3,4]
print(number[:])
[0, 1, 2, 3, 4]
What would you use if an element is to be removed from a specific index number?
del function
What is the output of the following code?
list1=[]
list1[1]=’hello’
print(list1[1][0])
This code produces an error
What is the output of the following code?
list1=[1,2,3]
list2=list1
list1[1]=7
print(list2)
None of these
'list1' [7,7,7] 7 [1,2,3] This code produces no output This code produces an error
What is the first negative index in a list?
-1
What method can be used to place an item in the list at a specific index?
insert
What is the output of the following code?
list1=[‘a’,’b’,’c’]
print(list1[3])
This code produces an error
What is the output of the following code?
list1 = [1, 2, 3, 4]
list1[3] = 10
print(list1)
None of these
[1, 10, 10, 10] [list1] [10] [1, 2, 10, 4] [1, 2, 3, 4] This code causes an error
What method or operator can be used to concatenate lists?
+
What is the ouput of the following code?
school = [‘primary’,’secondary’,[‘college’,’university’]]
print(school[2])
[‘college’, ‘university’]
What is the output of the following code?
count=0
days=['Monday','Tuesday','Wednesday','Thursday','Friday']
for a in days:
if count==2:
print("Results:",end="")
for b in range(2):
print(a,end="")
count+=1
Results:WednesdayWednesday
What is the output of the following code?
myList=['a','b','c','d','e']
z = 1
for x in range(5):
word=myList[x]
print(str(z),word,end="")
z+=1
1 a2 b3 c4 d5 e
What is the output of the following code?
count=0
list1=[0]*2
for item in list1:
if item==0:
count+=1
print(count)
2
What is the output of the following code?
a = ‘03/07/2014’
b = a.split(‘/’)
print(b)
[‘03’, ‘07’, ‘2014’]
Which statement would produce the value of the number of items in the list, list1?
None of these
What is the output of the following code?
list1=[6,4,65,7,12]
print(list1[-2:])
[7, 12]
Which of the following statements is true?
lists are mutable; strings are immutable
What is the output of the following code?
list1=[‘a’,’b’,’c’]
list1.remove(1)
print(list1)
This code causes an error
Given the following list, which statement will print out the character h?
list1=[[‘ab’,’cd’],[‘ef’,’gh’],[‘ij’,’kl’]]
print(list1[1][1][1])
What is the output of the following code?
list1=[‘h’,’e’,’l’,’l’,’o’]
list1.sort()
print(list1[0])
e
What is the output of the following code?
x=[2]
y=[7]
z=x+y
print(z)
[2, 7]
What is the output of the following code?
nums=[2,5,3,7]
if 5 in nums:
print('Yes')
else:
print('No')
Yes
What is the output of the following code?
person=[“Jane”,485,329]
print(person[1])
485
What is the output of the following code?
height=[72, 84, 67, 74]
print(max(height))
84
What is the output of the following code?
list1=[]
list1+=4
print(list1)
This code produces an error
In a dictionary, you use a(n) _____ to locate a specific value.
key
What is the correct structure for creating a dictionary of month names to be accessed by month numbers (only the first three months are given)?
{ 1 : ‘January’, 2 : ‘February’, 3 : ‘March’ }
What would be the result of the following code?
ages = {‘Aaron’ : 6, ‘Kelly’ : 3, ‘Abigail’ : 1 }
value = ages[1]
print(value)
This code generates an error
You created the following dictionary relationships = {‘Jimmy’:’brother’}. You then executed the following code, and received a KeyError exception. What is the reason for the exception?
relationships[‘jimmy’]
String comparisons are case sensitive so ‘jimmy’ does not equal ‘Jimmy’.
Which statement could you use to remove an existing key-value pair from a dictionary?
del
Which function would you use to get the number of elements in a dictionary?
len
Which method would you use to return all the keys in a dictionary and their associated values as a list of tuples?
items
What is the number of the first index in a dictionary?
None of these.
'A' 0 Size of the dictionary minus one. 1 -1
Which method would you use to return the value associated with a specified key and remove that key-value pair from the dictionary?
pop
The items method of a dictionary returns what type of value?
tuple
What does the get method do if the specified key is not found in the dictionary?
Returns a default value
In a dictionary, you use a(n) _____ to locate a specific value.
key
In order to avoid KeyError exceptions, you can check whether a key is in the dictionary using the _____ operator.
in
What is the output of the following code?
phones = {‘John’: ‘5555555’, ‘Julie’ : ‘7777777’}
phones[‘John’] = ‘1234567’
print(phones)
{‘John’: ‘1234567’, ‘Julie’: ‘7777777’}
What is the output of the following code?
d={0:’a’,1:’b’,2:’c’}
print(d[-1])
This code causes an error.
Which of the following is used to add a new item to a dictionary?
None of these
A dictionary can include the same value several times.
True
Which of the following statements will convert the values in a tuple named tuple1 to the values in a list named list1.
list1=list(tuple1)
Given that there is a large list and a large dictionary containing the same amount of data, when the programmer attempts to retrieve a particular piece of data from each structure, which of these statements is true?
Any speed difference will depend largely on the type of data stored, sometimes a list will be faster, sometimes a dictionary will be faster.
Dictionaries are mutable types. T/F
True
