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}; 

Answer 1

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\0\0\0\x08\0'  # Python 2 key = '\x13\0\0\0\x08\0' 

Answer 2

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'\x13\x00\x00\x00\x08\x00') 

Indexing get and sets the individual bytes

>>> key[0] 19 >>> key[1]=0xff >>> key bytearray(b'\x13\xff\x00\x00\x08\x00') 

and if you need it as a str (or bytes in Python 3), it's as simple as

>>> bytes(key) '\x13\xff\x00\x00\x08\x00'