\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.....

各种等效方法

使用打印

默认情况下，打印已经追加了换行符!

with open("out.txt", "w") as f:
    print("First", file=f)
    print("Second", file=f)

等同于:

with open("out.txt", "w") as f:
    print("First\nSecond", file=f)

要打印而不自动添加换行符，使用sep=""(因为sep="\n"是默认值):

with open("out.txt", "w") as f:
    print("First\nSecond\n", sep="", file=f)

使用f.write

对于以文本模式打开的文件:

with open("out.txt", "w") as f:
    f.write("First\nSecond\n")

对于以二进制模式打开的文件，写入文件时不会自动将\n转换为特定于平台的行结束符。要强制使用当前平台的换行符，请使用os。Linesep代替\n:

with open("out.txt", "wb") as f:
    f.write("First" + os.linesep)
    f.write("Second" + os.linesep)

输出文件

视觉:

First
Second

在Linux上，换行符将以\n分隔:

First\nSecond\n

在Windows中，换行符将以\r\n分隔:

First\r\nSecond\r\n

为了避免以文本模式打开的文件自动将\n转换为\r\n，请使用open("out.txt"， "w"， newline="\n")打开文件。

\n分隔字符串的行。在下面的示例中，我一直在循环中写入记录。每条记录以\n分隔。

f = open("jsonFile.txt", "w")

for row_index in range(2, sheet.nrows):

  mydict1 = {
    "PowerMeterId" : row_index + 1,
    "Service": "Electricity",
    "Building": "JTC FoodHub",
    "Floor": str(Floor),
    "Location": Location,
    "ReportType": "Electricity",
    "System": System,
    "SubSystem": "",
    "Incomer": "",
    "Category": "",
    "DisplayName": DisplayName,
    "Description": Description,
    "Tag": tag,
    "IsActive": 1,
    "DataProviderType": int(0),
    "DataTable": ""
  }
  mydict1.pop("_id", None)
  f.write(str(mydict1) + '\n')

f.close()

\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.....

简单的解决方案

如果只调用print而不带任何参数，它将输出一个空行。

print

你可以像这样将输出管道到一个文件中(考虑到你的例子):

f = open('out.txt', 'w')
print 'First line' >> f
print >> f
print 'Second line' >> f
f.close()

它不仅与操作系统无关(甚至不需要使用操作系统包)，而且比将\n放在字符串中更具可读性。

解释

print()函数有一个可选的关键字参数，用于字符串的结尾，称为end，默认为操作系统的换行符，例如。\ n。所以，当你调用print('hello')时，Python实际上打印的是'hello' + '\n'。这意味着当你只调用print而不带任何参数时，它实际上打印的是" + '\n'，结果是换行符。

替代

使用多行字符串。

s = """First line
    Second line
    Third line"""
f = open('out.txt', 'w')
print s >> f
f.close()

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.
"""))