Reading lines from text file in python (windows)

Python keeps the new line characters while enumerating lines. For example, when enumerating a text file such as

foo
bar

you get two strings: "foo\n" and "bar\n". If you don't want the terminal new line characters, you call strip().

I am not a fan of this behavior by the way.

See this.

Python is usually built with universal newline support; supplying 'U' opens the file as a text file, but lines may be terminated by any of the following: the Unix end-of-line convention '\n', the Macintosh convention '\r', or the Windows convention '\r\n'

You need the strip() because "for line in file:" keeps the line terminators on the lines. It's not explicitly stated in the docs (at least in the 2.71 doc I'm looking at). But it functions in a fashion similar to file.readline(), which does explicitly state that it retains the newline.

Try the following in a Python interpreter to see what the language does:

open('test1.txt', 'wb').write(b'Hello\nWorld!')
open('test2.txt', 'wb').write(b'Hello\r\nWorld!')
print(list(open('test1.txt'))) # Shows ['Hello\n', 'World!']
print(list(open('test2.txt'))) # Shows ['Hello\n', 'World!']

Python does recognize the correct newlines. Instead of using strip on your strings, you might want to write myString.replace('\n', '') instead. Check the documentation:

>>> help(str.strip)
Help on method_descriptor:

strip(...)
    S.strip([chars]) -> str

    Return a copy of the string S with leading and trailing
    whitespace removed.
    If chars is given and not None, remove characters in chars instead.

>>> help(str.replace)
Help on method_descriptor:

replace(...)
    S.replace(old, new[, count]) -> str

    Return a copy of S with all occurrences of substring
    old replaced by new.  If the optional argument count is
    given, only the first count occurrences are replaced.