python string写入二进制文件——直接wb形式open file，再write string即可

You misunderstood what \xhh does in Python strings. Using \x notation in Python strings is just syntax to produce certain codepoints.

You can use '\x61' to produce a string, or you can use 'a'; both are just two ways of saying give me a string with a character with hexadecimal value 61, e.g. the a ASCII character:

>>> '\x61'
'a' >>> 'a' 'a' >>> 'a' == '\x61' True

The \xhh syntax then, is not the value; there is no \ and no x and no 6 and 1 character in the final result.

You should just write your string:

somestring = 'abcd' with open("test.bin", "wb") as file: file.write(somestring)

There is nothing magical about binary files; the only difference with a file opened in text mode is that a binary file will not automatically translate \n newlines to the line separator standard for your platform; e.g. on Windows writing \n produces \r\n instead.

You certainly do not have to produce hexadecimal escapes to write binary data.

On Python 3 strings are Unicode data and cannot just be written to a file without encoding, but on Python the str type is already encoded bytes. So on Python 3 you'd use:

somestring = 'abcd' with open("test.bin", "wb") as file: file.write(somestring.encode('ascii'))

or you'd use a byte string literal; b'abcd'.