Explain the advantage of ‘x’ as value of mode parameter in open()

1.	Explain the advantage of ‘x’ as value of mode parameter in open() function.
Answer» Python’s built-in open() function returns a file object representing a disk file ALTHOUGH it can also be used to open any stream such as byte stream or network stream. The open() function takes two arguments: F=open(“filename”, mode) Default value of mode parameter is ‘r’ which STANDS for reading mode. To open a file for storing data, the mode should be set to ‘w’ f=open(‘file.txt’,’w’) f.write(‘Hello World’) f.close() However, ‘w’ mode causes OVERWRITING file.txt if it is earlier present, thereby the earlier saved data is at risk of being lost. You can of course check if the file already exists before opening, using os module function: import os if os.path.exists('file.txt')==False: f=open('file.txt','w') f.write('Hello world') f.close() This can create a race condition though because of simultaneous CONDITIONAL operation and open() functions. To avoid this ‘x’ mode has been introduced, starting from Python 3.3. Here ‘x’ stands for exclusive. Hence, a file will be opened for write operation only if it doesn’t exist already. Otherwise Python raises FileExistsError try: with open('file.txt','x') as f: f.write("Hello World") except FileExistsError: print ("File already exists") Using ‘x’ mode is safer than checking the existence of file before writing and guarantees avoiding accidental overwriting of files.

Explain the advantage of ‘x’ as value of mode parameter in open() function.

Answer»

Python’s built-in open() function returns a file object representing a disk file ALTHOUGH it can also be used to open any stream such as byte stream or network stream. The open() function takes two arguments:

F=open(“filename”, mode)

Default value of mode parameter is ‘r’ which STANDS for reading mode. To open a file for storing data, the mode should be set to ‘w’

f=open(‘file.txt’,’w’) f.write(‘Hello World’) f.close()

However, ‘w’ mode causes OVERWRITING file.txt if it is earlier present, thereby the earlier saved data is at risk of being lost. You can of course check if the file already exists before opening, using os module function:

import os if os.path.exists('file.txt')==False: f=open('file.txt','w') f.write('Hello world') f.close()

This can create a race condition though because of simultaneous CONDITIONAL operation and open() functions. To avoid this ‘x’ mode has been introduced, starting from Python 3.3. Here ‘x’ stands for exclusive. Hence, a file will be opened for write operation only if it doesn’t exist already. Otherwise Python raises FileExistsError

try: with open('file.txt','x') as f: f.write("Hello World") except FileExistsError: print ("File already exists")

Using ‘x’ mode is safer than checking the existence of file before writing and guarantees avoiding accidental overwriting of files.

Explain the advantage of ‘x’ as value of mode parameter in open() function.

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