Append string to bytearray

Question

I have a byte array, arr and a hexadecimal number a:

arr = bytearray()
a = 'FE'

How can I append this number to bytearray to have the same value, FE? I tried with print(int(a, 16)), but it seems to be a bad idea (it prints 254 instead of FE).

Possible duplicate of [Iron python: How to append string to bytearray](http://stackoverflow.com/questions/22656250/iron-python-how-to-append-string-to-bytearray) — Chanda Korat, May 18 '17 at 12:01
Everything is correct - you parse the hex value using `int` into an integer and then `print` outputs the decimal representation. `FE` in hex is `254` in dec. Just use `arr.append(int(a, 16))` and everything will be correct. Or you want to append it as a string, like two characters? — Eswcvlad, May 18 '17 at 12:02
@Eswcvlad: If `FE` is `254` that's fine. I forgot to recalculate this. So it seems ok now. Thanks! — yak, May 18 '17 at 12:08

score 3 · Accepted Answer · answered May 18 '17 at 12:02

3

The 254 is correct because 'FE' is hexadecimal for 254: F = 15, E = 14: 15 * 16**1 + 14 * 16**0 = 254

But if you want to append the characters you could use extend:

>>> arr = bytearray()
>>> arr.extend('FE'.encode('latin-1'))  # you can also choose a different encoding...
>>> arr
bytearray(b'FE')

answered May 18 '17 at 12:02

MSeifert

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How about use `ba = bytearray(b"FE")`? – stamaimer May 18 '17 at 12:06
@stamaimer Not sure what you mean, I thought the variable `'FE'` was given as variable (string), so you would need to convert it anyway (`encode`). – MSeifert May 18 '17 at 12:11

Append string to bytearray

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