Clarification about the close method in Python file handling

Question

I apologize if this will sound like a basic question but I'm seeking clarification on the close method in python, I am not understanding why after closing the file I can still print the variable that points to the file

if I run the below:

poem1 = open('poem1.txt', 'r') poem_line1 = poem1.readline() poem_line2 = poem1.readline() poem_line3 = poem1.readline() print(poem_line1 + poem_line2 + poem_line3) poem1.close() print(poem1.readline())

I will get the correct message:

"ValueError: I/O operation on closed file."

but if I replace the last line directly printing the file, there is no error:

 poem_line1 = poem1.readline() poem_line2 = poem1.readline() poem_line3 = poem1.readline() print(poem_line1 + poem_line2 + poem_line3) poem1.close() print (poem_line1 + poem_line2 + poem_line3)

What did you expect the first version of your code to do? Surely calling readline again should let you print the fourth line from the file, rather than re-printing the first three lines as your working version does. — Blckknght
– Blckknght, Commented Aug 30, 2019 at 6:47
Sorry, you’re right my code is a little misleading, in the second version of the code I could have put only one of the variable but I just wanted to understand why I could still print any of the variable when the file has been closed, but I guess I had my answer which is that the variable was in memory and that’s where I’m printing from and not from the file; that’s why I was confused :-) — Cedric
– Cedric, Commented Aug 30, 2019 at 14:17

micharaze · Accepted Answer · 2019-08-30 06:24:05Z

The line poem_line1 = poem1.readline() reads a line from the file and put it as a string in a variable. So after that the line is copied on the memory. This is the reason why you can still use this variable after closing the file.

So with the line print (poem_line1 + poem_line2 + poem_line3) you are not printing from the file, you are printing the string from the variables (from the memory).

Thanks a lot your answer is very appreciated my friend ,God bless!

Anoop R Desai · Accepted Answer · 2019-08-30 06:30:31Z

The method close() closes the opened file. A closed file cannot be read or written any more.

Any operation, which requires that the file be opened will raise a ValueError after the file has been closed.Python automatically closes a file when the reference object of a file is reassigned to another file. It is a good practice to use the close() method to close a file. Once you close the file you can not print those file because they are not open your compiler will not find anything.

This does not fully answer the question. Further, the last line is a little misleading.

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