Index binary type of a number

Question

b'1'[0]

The binary sequence of 1, when indexed is 49, I can't figure out why is it. Also the b'2'[0] is 50, what is the underlying binary sequence for the numbers?

Because ord('1') is 49. Likewise, chr(49) is '1'. There's a difference between characters (in a string) and integers. — Tom Karzes
– Tom Karzes, Commented Sep 10, 2021 at 11:35

Jasmijn · Accepted Answer · 2021-09-10 12:04:32Z

1

What you have there is no a "binary sequence", it is a bytes literal.

>>> type(b'1')
<class 'bytes'>

A bytes object is an immutable sequence of single bytes, so all numbers in this sequence have to be in range(0, 256)`. You can construct it from a list of numbers as well:

>>> bytes([50, 33])     
b'2!'

So what is this b'' notation all about?

Well, sequences of bytes are often related to text. Not always, but often enough that Python supports a lot of string methods on bytes objects, like capitalize, index and split, as well as this convenient literal syntax where you can enter text, and have it be equivalent to series of bytes corresponding to that text encoded in ASCII. It's still an immutable sequence of numbers in range(0, 256) under the hood, though, which is why indexing a bytes object gives a number.

answered Sep 10, 2021 at 12:04

Jasmijn

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