Python io.StringIO最后添加了额外的换行符

Question

It appears that Python's io.StringIO adds an extra newline at the end when I'm calling its getvalue method.

For the following code:

import io
s = io.StringIO()
s.write("1\n2\n3\n4\n5\n")
res = s.getvalue()
s.close()
print(res)

What I'm getting is this, with an extra newline in the end:

1
2
3
4
5

I checked the output with a hex editor, and I'm sure there's an extra newline.

The document says that:

The newline argument works like that of TextIOWrapper. The default is to consider only \\n characters as ends of lines and to do no newline translation . If newline is set to None, newlines are written as \\n on all platforms, but universal newline decoding is still performed when reading.

And I don't recall the write method append newlines per call.

So why is it adding newlines? I'm writing a script so I would like to make sure that it's behavior is consistent.

Answer 1

StringIO isn't doing this, it's print .

print prints all its arguments, seperated by sep (by default a space), and ending with end , by default a newline. You can suppress that by doing:

print(res, end="")