CODEWITHSUNDEEP
pythonbyte
Papipone
Papipone

Reputation: 1123

Declaring a single byte variable in Python

How do we declare a single byte variable in Python? I would like to achieve the following result represented in C:

unsigned char c = 0xFF;

I would like to know if it is possible to declare an 8-bit variable in Python.

Upvotes: 24

Views: 50159

Answers (3)

user3076105
user3076105

Reputation: 416

The answer depends on the python version.

$ python 
Python 2.7.5 (default, Mar 20 2020, 17:08:22) ...
>>> myba = bytes([0])
>>> myba[0] 
'['
>>> myba = bytearray([0])
>>> myba[0]
0
>>> 
$ python3
Python 3.6.8 (default, May  6 2020, 12:04:35) ...
>>> myba = bytes([0])
>>> myba[0]
0
>>> myba = bytearray([0])
>>> myba[0]
0
>>>

Upvotes: 0

user3076105
user3076105

Reputation: 416

The answer depends on python version.

$ python3
Python 3.6.8 (default, May  6 2020, 12:04:35) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> myba = bytes([0])
>>> myba[0]
0
>>> 
$ python 
Python 2.7.5 (default, Mar 20 2020, 17:08:22) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> myba = bytes([0])
>>> myba[0] 
'['
>>>

Upvotes: 0

ShadowRanger
ShadowRanger

Reputation: 155418

Python doesn't differentiate between characters and strings the way C does, nor does it care about int bit widths. For a single byte, you basically have three choices:

  1. A length 1 bytes (or bytearray) object mychar = b'\xff' (or mychar = bytearray(b'\xff'))
  2. An int that you don't assign values outside range(256) (or use masking to trim overflow): mychar = 0xff
  3. A ctypes type, e.g. mychar = ctypes.c_ubyte(0xff)

The final option is largely for dealing with C functions through ctypes, it's otherwise slow/not Pythonic. Choosing between options 1 and 2 depends on what you're using it for; different use cases call for different approaches (though indexing/iterating the bytes object would get you the int values if you need to use both forms).

Upvotes: 30

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