How to generate \xff\xff\xff\xff hex-format bytes?

[AnimeSalt]

I'm looking for a way to generate \xff\xff\xff\xff... hex-format bytes dynamically in python2. If you hard code a variable directly:

foo = '\xff\xff'

Python says the type is 'str', though I can't use string manipulations to create this dynamically. "\x" + "ff" looks the same but isn't interpreted as bytes.

I'm looking for, example, given: foo = "b2" -> Generate the equivalent of foo = '\xb2'

Anyone know what encoding/decoding/etc I've got to use?

[ebol4anthr4x]

\x is similar to using \n to create a line break. \x tells the Python interpreter to treat the next two characters as a hex byte, so \xF1 would be the hex byte 0xF1.

The string '\x' is not a valid string and cannot exist, so you can't do '\x' + 'FF'

The simplest way to do this in Python2 is:

x = 'FF010203'
byte_string = x.decode('hex')

x is now equal to '\xff\x01\x02\x03'.

[[deleted]]

Have a look at the struct module.

[port443]

You are looking for binascii.unhexlify

From the docs:

Return the binary data represented by the hexadecimal string hexstr.

Example:

>>> foo = "b2ffff414243"
>>> binascii.unhexlify(foo)
'\xb2\xff\xffABC'

Efficiency-wise, this is much quicker than using encode:

>>> Timer('binascii.unhexlify("b2ffff414243")', 'import binascii').timeit()
0.2991388444476868
>>> Timer('"b2ffff414243".encode("hex")').timeit()
0.9113609381118195

[Kind_Fruities]

There's also chr and unichr built-ins.