Byte to integer conversion

Question

If I use a function int.from_bytes() to convert a byte which is in a hexadecimal form it gives me a expected ans. But when the byte is in decimal form I get a unexpected value. I am not able to understand the math behind it, please explain. I am new to this my question may be silly, please try to understand from the example code below.

>>> testBytes = b'\x10'
>>> int.from_bytes(testBytes, byteorder='big', signed=True)
16
>>>testBytes1 = b'10'
>>>int.from_bytes(testBytes1, byteorder='big', signed=True)
12592

Here in the testBytes1 variable expected answer was 10, why I am getting such a big value, how does this function work, how will I get testBytes1 value as integer 10 as it is in the byte form. I am receiving testBytes1 over a usb port.

Stephen Rauch · Accepted Answer · 2020-02-07 06:32:06Z

3

That is simply taking the ascii value of each character:

Code:

testBytes1 = b'10'
print(int.from_bytes(testBytes1, byteorder='big', signed=True))

testBytes1 = b'\x31\x30'
print(int.from_bytes(testBytes1, byteorder='big', signed=True))

Results;

12592
12592

answered Feb 7, 2020 at 6:32

Stephen Rauch♦

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Comments

MartinKondor · Accepted Answer · 2020-02-07 06:32:30Z

1

You can convert bytes to a string, then convert it to an int.

>>> B = b'10'
>>> int(B.decode('utf-8'))
10

answered Feb 7, 2020 at 6:32

MartinKondor

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Comments

user12856906 · Accepted Answer · 2020-02-07 07:58:47Z

1

The most efficient way according to me is to decode the byte into string, and then converting it further to any required data type. Say, the byte is stored in variable n, then

x = n.decode('utf-8')

x, now will be a string, which can be converted to integer, float, or any data type required, by calling the respective constructor, as int(x)

answered Feb 7, 2020 at 7:58

user12856906

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