Python string representation of binary data

Question 1

I'm trying to understand the way Python displays strings representing binary data.

Here's an example usingos.urandom

In [1]: random_bytes = os.urandom(4)In [2]: random_bytesOut[2]: '\xfd\xa9\xbe\x87'In [3]: random_bytes = os.urandom(4)In [4]: random_bytesOut[4]: '\r\x9eq\xce'

In the first example ofrandom_bytes, after each \x there seem to be values in hexadecimal form: fd a9 be 87.

In the second example, however, I don't understand why'\r\x9eq\xce' is displayed.

Why does Python show me these random bytes in this particular representation? How should I interpret'\r\x9eq\xce'?

Question 2

It's only using the\xHH notation for characters that are (1) non-printable; and (2) don't have a shorterescape sequence.

To examine the hex codes, you could use thebinascii module:

In [12]: binascii.hexlify('\r\x9eq\xce')Out[12]: '0d9e71ce'

As you can see:

\r is the same as\x0d (it's the ASCII Carriage Return character, CR);
q is the same as\x71 (the latter is the hexASCII code of the former).

Question 3

"It's only using the \xHH notation for characters that are (1) non-printable; and (2) don't have a shorter escape sequence." Why is it so? Is there a way to prevent this, and see the hex representation instead of printable character or the escape sequence?

Question 4

\r is a carriage return, q is the q character - you should refer to their ASCII values (0x0d and 0x71)

Whenever python can - it will display the corresponding ASCII character, you'll only see \x when it can't (usually when the byte is higher than 0x79)

NPE 503k114 gold badges970 silver badges1k bronze badges · Accepted Answer · 2012-02-19 15:24:55Z

It's only using the\xHH notation for characters that are (1) non-printable; and (2) don't have a shorterescape sequence.

To examine the hex codes, you could use thebinascii module:

In [12]: binascii.hexlify('\r\x9eq\xce')Out[12]: '0d9e71ce'

As you can see:

\r is the same as\x0d (it's the ASCII Carriage Return character, CR);
q is the same as\x71 (the latter is the hexASCII code of the former).

"It's only using the \xHH notation for characters that are (1) non-printable; and (2) don't have a shorter escape sequence." Why is it so? Is there a way to prevent this, and see the hex representation instead of printable character or the escape sequence?

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Python string representation of binary data

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