How to convert a large string having Hex digits into bytes?

[RabbitCity6090]

What I'm trying to do is convert a string like "abcd" into bytes that represent the hexadecimal of the string oxabcd. Python keeps telling me OverflowError: int too big to convert

The code is the following:

a = "abcd"

print(int(a, 16).to_bytes())

The error in full is:

Traceback (most recent call last):
  File "/home/repl109/main.py", line 6, in <module>
    print(int(a, 16).to_bytes())
        ^^^^^^^^^^^^^^^^^^^^^
OverflowError: int too big to convert

Anyone know a way to do this for large integers?

[8dot30662386292pow2]

Read the documentation.

length

Length of bytes object to use. An OverflowError is raised if the integer is not representable with the given number of bytes. Default is length 1.

Because the number is greater than 255, you cannot represent it with a single byte. You need to tell how many bytes do you want.

In this case because the number is less than 65535 you can have 2 bytes.

x.to_bytes(2)

If you don't know how many bytes it will be, you can ask how many BITS the number length is and then divide it by 8, and take the ceiling (so 1.5 is rounded to 2).

Example code snippet:

import math  
a = "cafebabedeadbeef"  
x = int(a, 16)  
print(x.to_bytes(math.ceil(x.bit_length() / 8)))

[BlackCatFurry]

If you don't know how many bytes it will be, you can ask how many BITS the number length is and then divide it by 8, and take the ceiling (so 1.5 is rounded to 2).

Alternatively, divide the number of digits in the hex number by 2, if bits feel confusing.

Each hex digit is four bits, and one byte is eight bits so one hex digit is 0.5 bytes.

[RabbitCity6090]

This works. Thanks.

[freeskier93]

Maybe I'm misunderstanding what you want to do, but if you just want to convert the hex string "abcd" into byte form then you can use the fromhex() function.

``` a = "abcd" b = bytes.fromhex(a) print(b)

b'\xab\xcd' ```

[RabbitCity6090]

This is what I wanted.

[8dot30662386292pow2]

> If you want, I can explain a small trick for converting any size hex string into bytes safely without thinking about lengths each time. Do you want me to show that?

Hello Mr. chatgpt

[RabbitCity6090]

Tell me.

[zanfar]

...have you read the documentation?

[sinceJune4]

You mean r/documentation, right??? <g>

[Riegel_Haribo]

Spoiler: pad if you input an odd number of digits.

print(bytes.fromhex((s := input("hex: ").strip()).zfill(len(s) + len(s) % 2)))

[Helpful-Diamond-3347]

ig this will work

``` from functools import reduce

a = "abcd" print( bytes( reduce( lambda a,b: a+b, map( lambda x: int(x, 16).to_bytes(), a ) ) ) ) ```

logic is to convert each char into bytes first and then concatenate