为什么 \r\n output 变成 \r\r\n 使用 python 写入文件

Question

When I try to run the following code.

string = ['A', 'B', '\r', '\n', 'C', 'D']
print(''.join(string))
import io
with io.open(r"test.txt", "w", encoding="utf-8-sig", newline='\r\n') as f:
    f.write(''.join(string)+"\r\n")

the output to terminal is

AB
CD

but the output to txt file (using notepad++ to check), it becomes \r\r\n scr shot

how could I resolve it? (I don't want to change the input string . I want to keep it as \r\n )

I have tried to change the newlines, encoding. And search on google, however no luck.

Answer 1

Reading the open documentation about the newline argument, it says:

When writing output to the stream, if newline is None , any '\n' characters written are translated to the system default line separator, os.linesep . If newline is '' or '\n' , no translation takes place. If newline is any of the other legal values, any '\n' characters written are translated to the given string.

_{[Emphasis mine]}

By using newline='\r\n' you have explicitly told the system to translate any single newline '\n' into the carriage-return and newline pair '\r\n' . If you also write an explicit carriage-return, then you will write two carriage-returns (one from the data you write, one from the newline translation).

Change to either newline='' or newline='\n' to not do any translations.