7.3.1 - 7.3.2 File Input & Output

What does the 'r' argument do when opening a file?

• Opens a file for writing

• Opens a file for reading

• Opens a file for appending

• Opens a file for deleting

Answer explanation

The 'r' argument stands for 'read' and is used to open a file for reading its contents. This is why the correct answer is 'Opens a file for reading', as it allows you to access the data without modifying it.

Why is it important to call .close() after finishing with a file?

• To save memory

• To prevent data loss

• To delete the file

• To encrypt the file

Answer explanation

Calling .close() is crucial to prevent data loss because it ensures that all data is properly written to the file and resources are released. Failing to close a file can lead to incomplete writes and potential data corruption.

What function would you use to read the contents of a file into a variable?

• write()

• read()

• append()

• delete()

Answer explanation

The correct function to read the contents of a file into a variable is 'read()'. This function retrieves the data from the file, while 'write()', 'append()', and 'delete()' serve different purposes related to file manipulation.

What is the difference between 'r' and 'r+' when opening a file?

• 'r' is for reading, 'r+' is for writing only

• 'r' is for writing, 'r+' is for reading only

• 'r' is for reading, 'r+' is for reading and writing

• 'r' is for appending, 'r+' is for deleting

Answer explanation

The mode 'r' opens a file for reading only, while 'r+' opens it for both reading and writing. This means you can read from and write to a file with 'r+', making it more versatile than 'r'.

What happens if you open a file that already exists in 'w' mode?

• The file is deleted

• The file is appended

• The file is overwritten

• The file is encrypted

Answer explanation

Opening a file in 'w' mode will overwrite the existing file. This means any previous content in the file will be deleted and replaced with new content. Therefore, the correct answer is that the file is overwritten.

What character should be added at the end of a string to create a new line in a file?

• \t

• \n

• \r

• \b

Answer explanation

To create a new line in a file, you should add the character '\n' at the end of a string. This escape sequence represents a newline character, while '\t' is for a tab, '\r' is a carriage return, and '\b' is a backspace.

How is the 'a' mode different from 'w'?

• 'a' appends to the file, 'w' overwrites the file

• 'a' overwrites the file, 'w' appends to the file

• 'a' deletes the file, 'w' reads the file

• 'a' reads the file, 'w' deletes the file

Answer explanation

The 'a' mode appends data to the end of a file without deleting existing content, while the 'w' mode overwrites the entire file, erasing any previous data. Thus, the correct choice is that 'a' appends to the file, 'w' overwrites it.

When would using append mode be a better choice than write mode?

• When you want to overwrite the file

• When you want to delete the file

• When you want to add data without losing existing data

• When you want to encrypt the file

Answer explanation

Using append mode is better when you want to add data without losing existing data in a file. In contrast, write mode overwrites the entire file, which would erase any pre-existing content.

What line of code would you write to add 'Player score: 100' to the end of game_log.txt?

• open('game_log.txt', 'w').write('Player score: 100')

• open('game_log.txt', 'r').write('Player score: 100')

• open('game_log.txt', 'a').write('Player score: 100')

• open('game_log.txt', 'x').write('Player score: 100')

Answer explanation

The correct choice is 'open('game_log.txt', 'a').write('Player score: 100')' because 'a' mode appends to the file, adding the text at the end. 'w' overwrites, 'r' is for reading, and 'x' creates a new file, which is not suitable here.

What module and function are used to check if a file exists?

• os.path and exists()

• os and check()

• file and isfile()

• sys and path()

Answer explanation

The correct choice is 'os.path and exists()' because the 'os.path' module provides the 'exists()' function, which checks if a specified file or directory exists in the filesystem.