Binary Data, String, and Integer Conversions in Python

In Python 3, struct will interpret bytes as packed binary data:

This module performs conversions between Python values and C structs represented as Python bytes objects. This can be used in handling binary data stored in files or from network connections, among other sources.

>>> import struct
>>> struct.pack("<HH", 2, 8)
b'\x02\x00\x08\x00'
>>> struct.pack("BB", 0x31, 0x32)
b'12'
>>> "12"
'12'

There is no "bytes" type in Python 2. In Python 2, struct will interpret bytes as strings:

This module performs conversions between Python values and C structs represented as Python strings. This can be used in handling binary data stored in files or from network connections, among other sources.

>>> bytes is str

True

>>> struct.pack("<HH", 2, 8)'\x02\x00\x08\x00'
>>> struct.pack("<BB", 0x31, 0x32)'12'>>> "12"'12'

In Python 3,

int.to_bytes(length, byteorder, *, signed=False) will return an array of bytes representing an integer.

>>> a=0x1122334455

>>> b=a.to_bytes(5, byteorder="little")

>>> b.hex()

'5544332211'

int.from_bytes(bytes, byteorder, *, signed=False) will return the integer represented by the given array of bytes.

>>> c = int.from_bytes(b, byteorder="little")
>>> hex(c)
'0x1122334455'

If the integer is within 0~255, you can also use "bytes":

>>> bytes([0x11])

b'\x11'

I couldn't find the built-in method to convert long integer to bytes in Python 2. You can use "binascii" module instead.

String converts to bytes:

>>> s="123456"

>>> s.encode()

b'123456'

Integer converts to String: 

>>> s=hex(a)

>>> s

'0x1122334455'

binascii --- converts between binary and ASCII (string)

binascii.b2a_hex(data)
binascii.hexlify(data)
binascii.a2b_hex(hexstr)
binascii.unhexlify(hexstr)
binascii.crc32(data[, value])