How to unread a line in python

Question

I am new to Python (2.6), and have a situation where I need to un-read a line I just read from a file. Here's basically what I am doing.

  for line in file:
     print line
     file.seek(-len(line),1)
     zz = file.readline()
     print zz

However I notice that "zz" and "line" are not the same. Where am I going wrong?

Thanks.

Answer 1

I don't think for line in file: and seek make a good combination. Try something like this:

while True:
    line = file.readline()
    print line
    file.seek(-len(line),1)
    zz = file.readline()
    print zz

    # Make sure this loop ends somehow

Answer 2

You simply cannot mix iterators and seek() this way. You should pick one method and stick to it.