Fix Python – write() versus writelines() and concatenated strings

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Question

Asked By – AbeLinkon

So I’m learning Python. I am going through the lessons and ran into a problem where I had to condense a great many target.write() into a single write(), while having a "\n" between each user input variable(the object of write()).

I came up with:

nl = "\n"
lines = line1, nl, line2, nl, line3, nl
textdoc.writelines(lines)

If I try to do:

textdoc.write(lines)

I get an error. But if I type:

textdoc.write(line1 + "\n" + line2 + ....)

Then it works fine. Why am I unable to use a string for a newline in write() but I can use it in writelines()?

Python 2.7

Now we will see solution for issue: write() versus writelines() and concatenated strings

Answer

  • writelines expects an iterable of strings
  • write expects a single string.

line1 + "\n" + line2 merges those strings together into a single string before passing it to write.

Note that if you have many lines, you may want to use "\n".join(list_of_lines).

This question is answered By – DGH

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