What is the exact difference in writing a text file in text mode or byte mode?

Python Help
1

I have Python 2 code which looks like example a), and I think about whether I should leave it for Python 3 or convert it to binary and writing it in binary mode.

from datetime import datetime

# a
with open("check.log", "a") as f:
    content = "started at: %s\n" % datetime.today()
    f.write(content)

# b
with open("check.log", "ab") as f:
    content = "started at: %s\n" % datetime.today()
    content = content.encode("utf-8")
    f.write(content)

With both ways the text in the file looks the same. At least on my Ubuntu dev machine.

I’d appreciate any insight why this possible does not make any difference - or maybe when this makes a difference.

2

open docs:

In text mode, if encoding is not specified the encoding used is platform dependent: locale.getpreferredencoding(False) is called to get the current locale encoding.

So your first code snippet may or may not use UTF-8 encoding, e.g. on Windows it probably will not, currently. The second code snippet explicitly uses UTF-8.

When writing output to the stream, if newline is None , any '\n' characters written are translated to the system default line separator, os.linesep .

So your first code snippet may write \n or e.g. \r\n on Windows. The second code snippet will always write \n.

1 Like
3

Thank you! This makes sense.