Java字符串文字中的大多数转义字符在Python中也有效，例如“\r”和“\n”。

在Python 3中，该语言会在平台的原生表示中为你编码换行符。这意味着在Windows上是\r\n，而在成熟的系统上只是\n。

即使在U*x系统上，以文本模式读取Windows行结束符的文件也会返回正确的文本结果，即在\n字符之前的任何\r字符都会被无声地删除。

如果需要完全控制文件中的字节，则可以使用二进制模式。然后，每个字节恰好对应一个字节，Python不执行任何转换。

>>> # Write a file with different line endings, using binary mode for full control
>>> with open('/tmp/demo.txt', 'wb') as wf:
...     wf.write(b'DOS line\r\n')
...     wf.write(b'U*x line\n')
...     wf.write(b'no line')
10
9
7

>>> # Read the file as text
>>> with open('/tmp/demo.txt', 'r') as text:
...     for line in text:
...         print(line, end='')
DOS line
U*x line
no line

>>> # Or more demonstrably
>>> with open('/tmp/demo.txt', 'r') as text:
...     for line in text:
...         print(repr(line))
'DOS line\n'
'U*x line\n'
'no line'

>>> # Back to bytes!
>>> with open('/tmp/demo.txt', 'rb') as binary:
...     for line in binary:
...         print(line)
b'DOS line\r\n'
b'U*x line\n'
b'no line'

>>> # Open in binary, but convert back to text
>>> with open('/tmp/demo.txt', 'rb') as binary:
...     for line in binary:
...         print(line.decode('utf-8'), end='')
DOS line
U*x line
no line

>>> # Or again in more detail, with repr()
>>> with open('/tmp/demo.txt', 'rb') as binary:
...     for line in binary:
...         print(repr(line.decode('utf-8')))
'DOS line\r\n'
'U*x line\n'
'no line'

这里有一个更易读的解决方案，即使你不在顶级缩进(例如，在函数定义中)，它也能正确工作。

import textwrap
file.write(textwrap.dedent("""
    Life's but a walking shadow, a poor player
    That struts and frets his hour upon the stage
    And then is heard no more: it is a tale
    Told by an idiot, full of sound and fury,
    Signifying nothing.
"""))

这取决于你想要多正确。\n通常会做这项工作。如果你真的想要正确，你可以在os包中查找换行符。(这实际上叫做linesep。)

注意:当使用Python API写入文件时，不要使用os.linesep。只使用\n;Python会自动将其转换为适合您平台的换行符。

\n -简单换行符插入工作:

# Here's the test example - string with newline char:
In [36]: test_line = "Hi!!!\n testing first line.. \n testing second line.. \n and third line....."

输出:

In [37]: print(test_line)

Hi!!!
 testing first line..
 testing second line..
 and third line.....

正如在其他回答中提到的:“新的行字符是\n。它在字符串中使用”。

我发现最简单易读的方法是使用“format”函数，使用nl作为新行名称，并将你想打印的字符串转换为你要打印的确切格式:

Python 2:

print("line1{nl}"
      "line2{nl}"
      "line3".format(nl="\n"))

Python 3:

nl = "\n"
print(f"line1{nl}"
      f"line2{nl}"
      f"line3")

这将输出:

line1
line2
line3

通过这种方式，它可以执行任务，并且还提供了代码的高可读性:)