I/O

Question 1

What does a program do when it needs to save data for future use?

Answer 1

writes a data in a file. Normally used .txt files so far.

Question 2

Name some software that store data

Answer 2

Word processors
Image Editors
Spreadsheet
Games
Web browsers

Question 3

Programmers usually refer to storing data to a file as?

Answer 3

writing data to

Question 4

How is a piece of data written to a file?

Answer 4

copied from a variable in RAM to the file

Question 5

output file

Answer 5

used to describe a file that the data is written to

Question 6

Why is it called an output file?

Answer 6

because the program stores output in it

Question 7

What is the process of retrieving data from a file known as?

Answer 7

reading

Question 8

Input file

Answer 8

used to describe a file that is read from

Question 9

Why is it called an input file?

Answer 9

because the program gets the input from it

Question 10

What are the three steps that must be taken when a file is used by a program.

Answer 10

open the file
process the file
close the file

Question 11

Open the file

Answer 11

Opening a file creates connection between the file and the program.
Opening an output file creates a file on the disk and allows the program to write data to it.
Opening an input file allows to read the data from a file

Question 12

Process a file

Answer 12

In this step data is either written to the file or read from the file

Question 13

close a file

Answer 13

When the program is finished using the file, it must be closed. Closing a file disconnects the file from a program.

Question 14

What are the two types of files?

Answer 14

Binary and text

Question 15

A text file?

Answer 15

encoded as text using scheme : ASCII or unicode.

Viewable with text editors

Question 16

A binary file

Answer 16

not converted to text. Cannot be opened with text editors

Question 17

What are the two file access methods?

Answer 17

sequential

direct

Question 18

What is Sequential access file?

Answer 18

You access data from the beginning of the file to the end of the file. You cant jump around. Old tape. Cannot hop around. If you want to listen to track #5 have to listen to all tracks 1 -4

Question 19

What is Direct access file?

Answer 19

You can jump directly to any piece of data in the file without having to read the data that comes before it.
LIke MP3 players

Question 20

Direct access file is also known as?

Answer 20

Random access file

Question 21

What is a file object?

Answer 21

An object that is associated with a specific file and provides a way for the program to work with the file.

Question 22

What function do you use to open a file in Phyton?

Answer 22

open

Question 23

Syntax of writing to a file

Answer 23

FileWrite = open (“filename.txt”, someMode)

Question 24

Name the modes

Answer 24

r, w and a

Question 25

Describe the r mode

Answer 25

read only. The file cannot be changed or written to.

Question 26

Describe the w mode

Answer 26

open the file for write only. If file exists, delete the contents. If file does not exist, re-create it.

Question 27

Describe ‘a’ mode

Answer 27

Open a file to be written to. If a file exits, add to the end. If not creates it.

Question 28

test_file = open (r ‘c:\Blake\here.txt’, ‘w’)

What is r? Why is it needed?

Answer 28

raw string.

Otherwise \ will be considered as escape character and give out error.

Question 29

Syntax to write something to a file

Answer 29

FileWrite.write(string)

Question 30

Syntax to close

Answer 30

FileWrite.close()

Question 31

The data that is stored in a file is frequently organized in?

Answer 31

records and fields

Question 32

What is a record?

Answer 32

A complete set of data about an item

Question 33

What is a field?

Answer 33

An individual piece of data within a record.

Question 34

What is an exception?

Answer 34

An exception is an error that occurs when the program is running causing the program to abruptly halt.

Question 35

How can you handle exceptions?

Answer 35

use try/catch statements

Question 36

What is ‘traceback”?

Answer 36

It is an error message that gives information regarding the line numbers that caused exception.

Question 37

try:
(tab)statement
(tab)statement
what is this statement block called?

Answer 37

the try suite.

Question 38

What is created when an exception is thrown in the memory?

Answer 38

an exception object

Question 39

How do you display the default error message

Answer 39

except ValueError as sucks:

print(sucks)

Question 40

the else clause in the try/catch statement.
try:
   statement
except someerror:
   statement
else:
   statement
what is the block of statement after else called?
explain how this works.

Answer 40

else suite.
try some thing gets executed. If an exception is thrown, goes to the except and something is done. Does not go to else statement…
BUT if not exception is raised, skips the except and goes to else.

Question 41

Explain how finally clause in try/execute statement works.

Answer 41

finally at the end.
try:
statement
except:
statement
finally:
statement.
Now finally executes after try/except and whether or not the exceptions are raised or not raised.

Question 42

What is the purpose of finally?

Answer 42

For clean up operation. It closes files and other resources

Question 43

What if an exception is not handled?

Answer 43

It will cause the program to halt.

Question 44

What type of exception does a program raise when it tries to open an non-existence file?

Answer 44

IO error

Question 45

What type of exception does a program raise when float tries to convert to non-numeric string to number?

Answer 45

Value Error

Question 46

How do you handle multiple exceptions?

Answer 46

add as many except: statements