Byte Array in Python
Question:
How can I represent a byte array (like in Java with byte[]) in Python? I’ll need to send it over the wire with gevent.
byte key[] = {0x13, 0x00, 0x00, 0x00, 0x08, 0x00};
Answers:
In Python 3, we use the bytes
object, also known as str
in Python 2.
# Python 3
key = bytes([0x13, 0x00, 0x00, 0x00, 0x08, 0x00])
# Python 2
key = ''.join(chr(x) for x in [0x13, 0x00, 0x00, 0x00, 0x08, 0x00])
I find it more convenient to use the base64
module…
# Python 3
key = base64.b16decode(b'130000000800')
# Python 2
key = base64.b16decode('130000000800')
You can also use literals…
# Python 3
key = b'x13 x08 '
# Python 2
key = 'x13 x08 '
Dietrich’s answer is probably just the thing you need for what you describe, sending bytes, but a closer analogue to the code you’ve provided for example would be using the bytearray
type.
>>> key = bytearray([0x13, 0x00, 0x00, 0x00, 0x08, 0x00])
>>> bytes(key)
b'x13x00x00x00x08x00'
>>>
Just use a bytearray
(Python 2.6 and later) which represents a mutable sequence of bytes
>>> key = bytearray([0x13, 0x00, 0x00, 0x00, 0x08, 0x00])
>>> key
bytearray(b'x13x00x00x00x08x00')
Indexing get and sets the individual bytes
>>> key[0]
19
>>> key[1]=0xff
>>> key
bytearray(b'x13xffx00x00x08x00')
and if you need it as a str
(or bytes
in Python 3), it’s as simple as
>>> bytes(key)
'x13xffx00x00x08x00'
An alternative that also has the added benefit of easily logging its output:
hexs = "13 00 00 00 08 00"
logging.debug(hexs)
key = bytearray.fromhex(hexs)
allows you to do easy substitutions like so:
hexs = "13 00 00 00 08 {:02X}".format(someByte)
logging.debug(hexs)
key = bytearray.fromhex(hexs)
How can I represent a byte array (like in Java with byte[]) in Python? I’ll need to send it over the wire with gevent.
byte key[] = {0x13, 0x00, 0x00, 0x00, 0x08, 0x00};
In Python 3, we use the bytes
object, also known as str
in Python 2.
# Python 3
key = bytes([0x13, 0x00, 0x00, 0x00, 0x08, 0x00])
# Python 2
key = ''.join(chr(x) for x in [0x13, 0x00, 0x00, 0x00, 0x08, 0x00])
I find it more convenient to use the base64
module…
# Python 3
key = base64.b16decode(b'130000000800')
# Python 2
key = base64.b16decode('130000000800')
You can also use literals…
# Python 3
key = b'x13 x08 '
# Python 2
key = 'x13 x08 '
Dietrich’s answer is probably just the thing you need for what you describe, sending bytes, but a closer analogue to the code you’ve provided for example would be using the bytearray
type.
>>> key = bytearray([0x13, 0x00, 0x00, 0x00, 0x08, 0x00])
>>> bytes(key)
b'x13x00x00x00x08x00'
>>>
Just use a bytearray
(Python 2.6 and later) which represents a mutable sequence of bytes
>>> key = bytearray([0x13, 0x00, 0x00, 0x00, 0x08, 0x00])
>>> key
bytearray(b'x13x00x00x00x08x00')
Indexing get and sets the individual bytes
>>> key[0]
19
>>> key[1]=0xff
>>> key
bytearray(b'x13xffx00x00x08x00')
and if you need it as a str
(or bytes
in Python 3), it’s as simple as
>>> bytes(key)
'x13xffx00x00x08x00'
An alternative that also has the added benefit of easily logging its output:
hexs = "13 00 00 00 08 00"
logging.debug(hexs)
key = bytearray.fromhex(hexs)
allows you to do easy substitutions like so:
hexs = "13 00 00 00 08 {:02X}".format(someByte)
logging.debug(hexs)
key = bytearray.fromhex(hexs)