How to assign a hex literal to a `bytes` variable in Solidity

Question

I am trying to put 0x11 into bytes, but I keep getting an error.

As I know, the bytes type supports the flexible size up to 32 bytes. However, I do not know what I can't even set 1 byte there.

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.0 <0.9.0;

contract practice {
    bytes1 public a = 0x11;
    bytes  public c = 0x11; // an error occured, why is it??
    bytes public b = '0x11'; // It is not even 0x11, why do I have to put string value into bytes...? 
}

Please let me know this

Answer 1

0x11 is an integer constant. This type is not implicitly convertible to bytes and there's no explicit conversion but you can use bytes.concat() function for that:

bytes public c = bytes.concat(0x11);

In this case, however what you really want is a hexadecimal literal:

bytes public c = hex"11";

bytes public b = '0x11'; // It is not even 0x11, why do I have to put string value into bytes...?

This does not put the number 0x11 in your variable. It puts 0x30783131 in it instead - i.e. the hexadecimal values of the ASCII characters in your string. It's wrong.