In python3 I can't get -1 to print 0xFF. Is there a way?

Question

How would I get the various outputs below to come out 0xFF or 0xFFFF?

>>> key=-1
>>> print(key)
-1
>>> print(hex(key))
-0x1
>>> print("Key={:4X}".format(key))
Key=  -1
>>>

Answer 1

You could try something like that:

>>> def do_what_you_want(number, length):
...     print(hex(number+(1<<(length*4))))
...
>>> do_what_you_want(-1, 2)
0xff
>>> do_what_you_want(-1, 4)
0xffff

Answer 2

Python integers are arbitrary precision – -1 cannot "wrap around" to the maximum value.

Explicitly wrap the number(s) to the desired range:

>>> key = -1
>>> hex(key % 256)    # restrict to range 0-255
0xff
>>> hex(key % 65536)  # restrict to range 0-65535
0xffff