Is file object in python an iterable

Question

I have a file \"test.txt\":

this is 1st line
this is 2nd line
this is 3rd line

the following code

lines = open(\"test.txt\"         


        

Answer 1

Yes, file objects are iterators.

Like all iterators, you can only loop over them once, after which the iterator is exhausted. Your file read pointer is at the end of the file. Re-open the file, or use .seek(0) to rewind the file pointer if you need to loop again.

Alternatively, try to avoid looping over a file twice; extract what you need into another datastructure (list, dictionary, set, heap, etc.) during the first loop.