CSE Crowson MSU Exam 3

The write() method immediately writes data to a file

False

file.write() method

writes a string argument to a file

a mode:

indicates how a file is opened

most used modes are:

'r' (read), 'w' (write)

mode 'a':

Open the file for appending

mode 'r'

Open the file for reading

mode 'w':

Open the file for writing.

The flush() file method can:

force the interpreter to flush the output buffer to disk

The statement f.write(10.0) always produces an error

True

The flush() method (and perhaps os.fsync()) forces the output buffer to write to disk

True

binary data

data stored as a sequence of bytes

bytes object

a sequence of single byte values

For a program run as "python scriptname data.txt", what is sys.argv[1]?

data.txt

A script "myscript.py" has two command line arguments, one for an input file and a second for an output file. Type a command to run the program with input file "infile.txt" and output file "out".

> python myscript.py infile.txt out

When using a with statement to open a file, the file is automatically closed when the statements in the block finish executing.

True

file.close() method

closes the file

file.write() method

writes a string argument to a file

the process of responding to unexpected or unwanted events and errors during execution

exception handling

EOFerror

input() hits an end-of-file condition (EOF) without reading any input

KeyError

A dictionary key is not found in the set of keys

ZeroDivisionError

Division by zero

ValueError

Invalid value

IndexError

Accessing an index that is out of range

Set:

unordered linear data type, every element is unique, using curly braces

set.intersection

Returns a new set containing only the elements in common between set and all provided sets.

set.union

Returns a new set containing all of the unique elements in all sets.

set.difference

Returns a set containing only the elements of set that are not found in any of the provided sets

len(set)

Find the length (number of elements) of the set.

set1.update(set2)

Adds the elements in set2 to set1.

set.add(value)

Adds value into the set.

set.remove(value)

Removes value from the set. Raises KeyError if value is not found.

set.pop()

Removes a random element from the set.

set.clear()

Clears all elements from the set.

A dictionary entry is accessed by placing a key in curly braces { }.

False

Dictionary entries are ordered by position.

True

dict[ ] =

adds elements to a dictionary or overwrites a value

When you open a file in write mode:

it automatically erases the file contents

When you write to a file that does not exist:

it creates that file

What are CSV files?

text based file that uses commas to separate data items

What is the purpose of exception handling?

To handle errors gracefully so the program does not crash.

Where do errors occur?

Inside the try block

If Python finds a error in the try block:

python quits running the code and moves the except block

What does the except block do?

It prints a message to the user stating an error has occurred

What are the two primary components to a class?

methods and attributes

What is the responsibility of the _init_ method?

initializes values to attributes

What is the self method?

referring the instance of class, calling the method

How do you access the attributes of a class?

Using a dot operator

What is better than accessing the attributes of a class?

using setters and getters

What is the difference between a tuple and list?

Tuples are immutable