Convert a H256 string to H256

Question

I have a hash string "0xf8dd02cc2a3174933fac4e87d7f6360c3cc67167db105b28d0bc434a60674e49". How can i convert back to H256.

I used function below but it return difference H256 0xa8fb46593dfc218a4de6fcf14e0c9baa4bcf947b953c181689015793883b3a1d

let hex_string = "0xf8dd02cc2a3174933fac4e87d7f6360c3cc67167db105b28d0bc434a60674e49".as_bytes().to_vec();
info!("{:?}", hex_string);
let hex_string_hash = hash::<Runtime>(&hex_string);
info!("{:?}", hex_string_hash);

---

pub fn hash<Runtime>(data: &[u8]) -> H256
where
    Runtime: frame_system::Config,
    H256: From<<Runtime as frame_system::Config>::Hash>,
{
    <Runtime as frame_system::Config>::Hashing::hash(data).into()
}

---

Edit: As aurevoirxavier answer. I have updated my code like this:

use primitive_types::H256;
fn main() {
    let hex = "0xf8dd02cc2a3174933fac4e87d7f6360c3cc67167db105b28d0bc434a60674e49";
    match array_bytes::hex_n_into::<H256, 32>(hex) {
        Ok(h256) => {
            println!("{:?}", h256);
        }
        _ => (),
    }
}

Answer 1

I recommend using array-bytes, see https://github.com/paritytech/substrate/pull/12190.

let hex = "0xf8dd02cc2a3174933fac4e87d7f6360c3cc67167db105b28d0bc434a60674e49";
if let Ok(h256) = array_bytes::hex_n_into::<H256, 32>() {
    info!("{:?}", h256);
}

---

For your steps, you should remove the 0x prefix. It isn't a part of bytes.

With array-bytes, it will handle this automatically.

Answer 2

if you don't want to remove '0x',you could use Macro ckb_types::h256 in https://docs.rs/ckb-types/0.110.0/ckb_types/macro.h256.html :

use ckb_types::h256;
h256!("0xf8dd02cc2a3174933fac4e87d7f6360c3cc67167db105b28d0bc434a60674e49")

with cargo.toml: ckb-types = "0.108"