Why \r\n output become \r\r\n using python write to file-CodePudding

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.

CodePudding user response：

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.