How to convert byte array to hex string?

Question

Here is the sample code in JS :

function toHexString(bytes) {
  return bytes.map(function(byte) {
      return ("00" + (byte & 0xFF).toString(16)).slice(-2);
    }).join('');
}

input -> Buffer.from("333138383223633D77DB", 'hex')
output -> 333138383223630770

Here is what I have tried so far in Python

def toHexString(byteArray):
    return ''.join('{:02x}'.format(x) for x in byteArray)


input -> bytearray.fromhex("333138383223633D77DB")
output -> 333138383223633d77db

I think the logic is correct but does not know what is wrong

My expectation result of the Python code should be similar to the result of JS code.

I would like to ask how should I update the python code to get the exact result as JS code

That JS code doesn't really make a lot of sense, the output is different from the input so toHexString doesn't do what its name suggests. — robertklep
– robertklep, Commented Jan 13, 2023 at 15:23
With "wrong" do you mean the JavaScript code or something in the Python code (in the latter case, explain what you expect instead)? — Michael Butscher
– Michael Butscher, Commented Jan 13, 2023 at 15:31
@ChauLoi but your JS code is broken, it does not output a hex string that is equal to the input. — robertklep
– robertklep, Commented Jan 13, 2023 at 15:45
The output shown (both variants) are similar. They are not however identical. What do you actually want? — jackal
– jackal, Commented Jan 13, 2023 at 15:53

robertklep · Accepted Answer · 2023-01-18 14:50:27Z

1

Your Python code is correct (although it can be written much more concise as the other answers suggest), but your JS code isn't because it clearly outputs a hex string that is not the same as the input.

Instead, fix your JS code:

function toHexString(bytes) {
  return bytes.toString('hex').toUpperCase();
}

input -> Buffer.from("333138383223633D77DB", 'hex')
output -> 333138383223633D77DB

EDIT: if you really insist on Python code that outputs the same broken hex string, this may work:

import re

input  = '333138383223633D77DB';
output = ''
for m in re.finditer(r'..', input):
    match = m.group(0)
    output += match if re.match('[0-9][0-9]', match) else '0'
print(output)

(my Python skills are extremely rusty so it may not work for all inputs, and/or it can be written much more concise)

edited Jan 18, 2023 at 14:50

answered Jan 13, 2023 at 16:07

robertklep

205k38 gold badges421 silver badges412 bronze badges

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

3 Comments

Chau Loi Over a year ago

I actually expect the response of 333138383223630770

jackal Over a year ago

@ChauLoi Please explain the logic behind that transformation

Chau Loi Over a year ago

@Pingu I am working on this document github.com/loichau1997/Strega/blob/master/…

Endless · Accepted Answer · 2023-01-13 15:37:01Z

1

with python 3.5+ you can use hex()

def toHexString(byteArray):
    return byteArray.hex()

honestly do not think there is any need for defining any helper function when you can just run byteArray.hex()

answered Jan 13, 2023 at 15:37

Endless

38.8k14 gold badges118 silver badges138 bronze badges

2 Comments

robertklep Over a year ago

Well, the question is that the Python code returns the same as the JS code, which it doesn't (because the JS code is broken).

Chau Loi Over a year ago

hi I want to have the response of 333138383223630770

jackal · Accepted Answer · 2023-01-13 16:08:09Z

1

As has already been stated, there is built-in functionality for this in Python. However, if you insist on re-inventing the wheel then:

hs = '333138383223633D77DB'

def toHexString(ba):
    return ''.join([f'{b:02X}' for b in ba])

assert toHexString(bytearray.fromhex(hs)) == hs

Note the use of uppercase 'X' in the format specifier.

Also worth mentioning that bytearray.hex() returns a string in ASCII lowercase

edited Jan 13, 2023 at 16:08

answered Jan 13, 2023 at 16:01

jackal

29.1k3 gold badges9 silver badges27 bronze badges

1 Comment

Chau Loi Over a year ago

hi I actually want to have the response of 333138383223630770

Collectives™ on Stack Overflow

How to convert byte array to hex string?

3 Answers 3

3 Comments

2 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related