Non-binary(hex) characters in string received over TCP with Python

Question

maybe this is a noob question, but I'm receiving some data over TCP and when I look at the string I get the following:

\x00\r\xeb\x00\x00\x00\x00\x01t\x00

What is that \r character, and what does the t in \x01t mean?

I've tried Googling, but I'm not sure what to Google for...

thanks.

Doesn't look much like any encoding I can think of (four NULL bytes in a row?). Looks more like binary data, I'd say... — Tim Pietzcker
– Tim Pietzcker, Commented Oct 11, 2010 at 14:06
It is a response I get from a traffic simulator with a TCP server, and I have to parse it myself based on the length(1st byte) and the command(2nd byte), so how do I interpret the r and the t? — Niel de Wet
– Niel de Wet, Commented Oct 11, 2010 at 14:10
In hex, this is 00 0d eb 00 00 00 00 01 74 00. \r, carriage return, is the same as 0x0d and the letter t corresponds to 0x74. — Bernd Petersohn
– Bernd Petersohn, Commented Oct 11, 2010 at 14:19
-1: Don't ask us. Who is sending the data? Ask them. They actually know what data they're sending. — S.Lott
– S.Lott, Commented Oct 11, 2010 at 20:12

Blrfl · Accepted Answer · 2010-10-11 14:04:29Z

9

\r is a carriage return (0x0d), the t is a t.

answered Oct 11, 2010 at 14:04

Blrfl

7,0331 gold badge28 silver badges26 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Niel de Wet Over a year ago

If that's the case, why isn't it given simply as 0x0d?

Blrfl Over a year ago

Because there's a standard escape, \r, designated for it. Search for "C character escapes" and you'll find a table of how they're represented.

Humphrey Bogart Over a year ago

@nieldw Python represents bytes objects as strings of hex values identifying each byte, except when the hex value is that of a printable/commonly used ASCII value.

Nick T · Accepted Answer · 2010-10-11 21:07:12Z

4

Viewing binary data in strings can sometimes be confusing, especially if they're long, but you can always convert it to some easier-to-read hex.

>>> data = '\x00\r\xeb\x00\x00\x00\x00\x01t\x00'
>>> ' '.join(["%02X" % ord(char) for char in data])
'00 0D EB 00 00 00 00 01 74 00'

Also, if you're just parsing the byte string into fields, just ignore the string and just go right to unpacking it with the struct module:

>>> import struct
>>> length, command, eggs, spam = struct.unpack('!BBi4s',data)
>>> #...whatever your fields really are
>>> print "len: %i\ncmd: %i\negg qty: %i\nspam flavor: '%s'" % (
...     length, command, eggs, spam)
len: 0
cmd: 13
egg qty: -352321536
spam flavor: ' ☺t '

edited Oct 11, 2010 at 21:07

answered Oct 11, 2010 at 15:08

Nick T

26.9k14 gold badges88 silver badges128 bronze badges

Comments

Mark Tolonen · Accepted Answer · 2010-10-11 16:28:18Z

2

When displaying data as a string, printable characters (such as 't' are displayed as characters, known control sequences are displayed as escapes, and other bytes are displayed in \x## form. Example:

>>> s='\x74\x0d\x99'
>>> s
't\r\x99'

You can dump a hexadecimal form with:

>>> import binascii
>>> binascii.hexlify(s)
'740d99'

answered Oct 11, 2010 at 16:28

Mark Tolonen

181k26 gold badges182 silver badges278 bronze badges

Collectives™ on Stack Overflow

Non-binary(hex) characters in string received over TCP with Python

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related