How can for File IO works in Python?

Question

I have finished pset5 and now on pset6 but I have one doubt about how we can read the file without file.read() or readlines() etc.

I understand both code

file = open(“testfile.txt”, “r”) 
c = file.read()
print(c)

OR

with open('file.txt') as fp:
    lines = fp.read()

But how this can work, how can for loop read file without reading

file = open(“testfile.txt”, “r”) 
for line in file: 
    print(line)

Even David M uses formeathod in week 8 lectures to port speller load function in python.
If this is features then how both are different?

Answer 1

Python file objects are also iterators, that's how for uses them. It keeps calling the iterator's next method, which spits out a single line at a time.

Just don't combine this implicit next and any kind of read.