How to convert from string to 16-bit unsigned integer in python?

Question

I'm currently working on some encoding and decoding of the string in python. I was supposed to convert some code from C# to python, however I encountered some problem as below:

So now I have a string that looks like this: 21-20-89-00-67-00-45-78 The code was supposed to eliminates the - in between the numbers, and packed 2 integers into 1 group, then convert them into bytes. In C#, it was done like this:

var value = "21-20-89-00-67-00-45-78";
var valueNoDash = value.Replace("-", null);
for (var i = 0; i < DataSizeInByte; i++)
{
    //convert every 2 digits into 1 byte
    Data[i] = Convert.ToByte(valueNoDash.Substring(i * 2, 2), 16);
}

The above code represents Step 1: Remove - from the string, Step 2: using Substring method to divide them into 2 digits in 1 group, Step 3: use Convert.ToByte with base 16 to convert them into 16-bit unsigned integer. The results in Data is

So far I have no problem with this C# code, however when I try to do the same in python, I could not get to the same result as the C# code. My python code are as below:

from textwrap import wrap
import struct

values = "21-20-89-00-67-00-45-78"
values_no_dash = a.replace('-', '')
values_grouped = wrap(b, 2)
values_list = []

for value in values_grouped:
    values_list.append(struct.pack('i', int(value)))

In python, it gives me list of bytes in hex value, which is as below:

b'\x15\x00\x00\x00'
b'\x14\x00\x00\x00'
b'Y\x00\x00\x00'
b'\x00\x00\x00\x00'
b'C\x00\x00\x00'
b'\x00\x00\x00\x00'
b'-\x00\x00\x00'
b'N\x00\x00\x00'

This is in bytes object, however when I converted this object into Decimal, it gives me the exact same value as the original string: 21, 20, 89, 0, 67, 0, 45, 78.

Which means I did not convert successfully into 16-bit unsigned integer right? How can I do this in python? I've tried using str.encode() but the result still different. How can I achieve what C# had done in python?

Thanks and appreciates if anyone can help!

It's unclear to me how converting 21 results in 33 (or any of the other supposedly "correct" conversions). Please edit your question and explain better how this packing of 2 integers into 1 group which is then converted a byte works. — martineau
– martineau, Commented Oct 4, 2019 at 1:04
@martineau The packing of 2 integers into 1 group is because after eliminates the - in the string, the digits will stick together, and I want them to be converted to uint as their original pairs which is 21, 20, 89 instead of 2, 1, 2, 0, 8, 9... For the conversion, the method Convert.ToBytes with parameters 16 means that it will convert the number from base 16 to base 10. — Sivvie Lim
– Sivvie Lim, Commented Oct 4, 2019 at 1:17

Michele Bastione · Accepted Answer · 2019-10-04 01:12:43Z

2

I think this is the solution you're looking for:

values = "21-20-89-00-67-00-45-78"
values_no_dash_grouped = values.split('-') #deletes dashes and groups numbers simultaneously 
for value in values_no_dash_grouped:
    print(int(value, 16)) #converts number in base 16 to base 10 and prints it

Hope it helps!

edited Oct 4, 2019 at 1:12

answered Oct 4, 2019 at 1:06

Michele Bastione

3633 silver badges13 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Sivvie Lim Over a year ago

Hi yes it is!! Thank you so much!!

Collectives™ on Stack Overflow

How to convert from string to 16-bit unsigned integer in python?

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related