Questions tagged [bytes]
both the fixed-size array byte, bytes1...bytes32, and the dynamic array bytes types in Solidity
191
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Why "It's better to use the bytes type instead of the bytes1[] type"? Solidity
I read a Note in documentation of Solidity:
The type bytes1[] is an array of bytes, but due to padding
rules, it wastes 31 bytes of space for each element (except in
storage). It is better to use the ...
0
votes
0
answers
123
views
Uniswap v3: How do I get the path bytes from solidity from array function parameters?
I am trying to write a smart contract that can facilitate multihop swaps. It is important that I am able to pass in 2 arrays into the swap function: an address[] of the tokens and uint256[] of the ...
- 1
0
votes
1
answer
61
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Simple contract fails to deploy to Sepolia
I am trying to deploy a very simple contract to Sepolia.
Here is the code:
pragma solidity ^0.8.18;
contract Object {
bytes32 private UID;
bytes private Desc;
constructor(...
- 515
0
votes
1
answer
84
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How to encode arbitrary amount of parameters for encodeWithSignature without adding them to function definition?
Lets says we have Contract A that needs to call Contract B at a certain address which the requirements that Contract A doesn't know the exact parameter structure the function in that Contract B needs &...
- 61
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126
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Calculate the contract address created using create2 with dynamic byte string as a salt
EIP-1014 describes salt as bytes32.
However, the function create2 written in assembly allows passing byte string of arbitrary size as the salt parameter.
Example
function deploy(bytes memory bytecode, ...
- 415
0
votes
1
answer
32
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Chainlink Functions return an array or list of strings from Functions-request-source.js
Hope someone can help.
I am stuck trying to work out how best to extract the different string values from the returned bytes data.
Chainlink Function request source requires the return value to be a ...
- 15
0
votes
1
answer
22
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Unintentional extra arguments on calldata
I manually inserted 2 32 bytes arguments to a function flipSwitch(bytes memory someData) whose function identifier happens to be 0x30c13ade.
My manual arguments:
...
- 41
0
votes
1
answer
29
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mapping not showing any value corresponding to string key(converted from bytes32)
I have bytes32 data which needs to be converted into a string, then use to get value from mapping(string => string)
Trying to convert bytes32 to string using : string(abi.encodePacked(temp))
It is ...
0
votes
0
answers
9
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Expected Primary Expression error on signature function
With this isValidSignature function:
// NOTE: This method not safe, contract may attack by signature replay.
/**
* Verify if the signer has a valid signature as claimed
* @param signer ...
- 133
2
votes
4
answers
64
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How to batch list into a single bytes object?
Let's say I have a string list of parameters
["Example String", "vitalikbuterin", "1000"]
How can I encode this list into a bytes object, and then decode the bytes to get ...
- 35
1
vote
1
answer
29
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Can someone explain to me how returns work under the hood in solidity?
Can someone explain how I will be successfully able to return this
function reddish(uint256 _red) public view returns (bytes memory) {
bytes memory err = abi.encode(msg.sender, _red);
assembly ...
- 54
3
votes
2
answers
593
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How to convert `bytes4` to `bytes memory` in Solidity?
bytes4 is a commonly needed data type in Solidity, due to its use in msg.sig and, more broadly speaking, in function selectors (e.g. Contract.func.selector).
How can one convert bytes4 to bytes memory?...
- 16.7k
1
vote
1
answer
105
views
How exactly does the 'hex' prefix work for bytes?
I found some code snippets using the 'hex' prefix before a string in a bytes variable. I can't seem to find its description in the solidity docs.
bytes memory bytesVar = "0x01";
bytes ...
- 302
0
votes
1
answer
360
views
Encode Struct[] in ethers to pass to a dynamic bytes
I have a method in solidity:
function getVotesWithParams(
address account,
uint256 blockNumber,
bytes memory params
) public view virtual override returns (uint256) {
return _getVotes(...
- 271
1
vote
1
answer
833
views
How to decode `encodePacked` data
I have two addresses, _token1 and _token2. I would like to pack them into bytes data to pass it to a function.
bytes memory params = abi.encode(_token1, _token2);
The obtained params is the ...
- 177
0
votes
2
answers
207
views
Convert bytes20 to address in assembly
Can you convert a bytes20 to address in assembly (not solidity-typecasting)?
If so, how?
- 675
0
votes
1
answer
44
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Grab the last 32 bytes of 64-bytes input
In assembly, how do I grab the last 32 bytes in a 64-bytes input?
I know that this code is for grabbing the first 32:
bytes32 half;
assembly {
half := mload(add(accData2, 32))
}
- 675
0
votes
1
answer
118
views
TypeError: Member "encodeCall" not found or not visible after argument-dependent lookup in abi
I am trying to test abi.encodeCall on Remix. I have this function
function getTestData() external pure returns (bytes memory){
// passing empty args ()
return abi.encodeCall(TargetContract.send,());
}
...
- 1,492
0
votes
1
answer
50
views
How to pass bytes4 to mapping?
I'm trying to pass bytes4 type to mapping but all I have got is an error saying:
**ParserError: Expected identifier but got '='**
bytes4 example = 0x11030330;
mapping(bytes4 => address) facets;
...
- 33
1
vote
0
answers
64
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How to handle both String and Bytes return types in Rust
I'm trying to query the MAKER ERC20 contract and get the name and symbol of the token.
The problem is that they are stored as a Bytes and I don't want to change the return type of my function from a ...
- 11
1
vote
1
answer
925
views
Unable to deduce common type for array elements in bytes[ ]. Why I am getting this even the first line works perfectly but 2nd one's throws error?
I am trying to get understanding of bytes array but encountered an error where,
contract Mytest {
>
> bytes[] public arr1 = [bytes("happy"), "names"]; // This line ...
0
votes
2
answers
74
views
bytes5 vs string
I have an smart contract with some defined fixed length variables from 3 to 5 characters long.
Defining these variables as string is more intuitive for those that come from another languages. Also ...
- 119
3
votes
2
answers
1k
views
How to decode the output of an eth_call that returns a Tuple[]
I am developing a low-level library that interacts with RPC nodes directly. There is a requirement to call the AaveV2 getAllReserveTokens function, and I want to decode the output data.
The particular ...
- 121
2
votes
1
answer
83
views
How to reverse a Solidity bytes sorting?
Suppose I have this bytes pad:
0x0123456789abcdef
How can I make it like this:
0xfedcba9876543210
Just by Solidity and not by Assembly.
- 533
0
votes
1
answer
46
views
get uint value inside a bytes32 slice
I have the following code:
function test_bytes(bytes32 test) external pure returns(bytes3 idx,uint256 idx2)
{
//test = ...
- 1
1
vote
1
answer
591
views
Multiple matching functions error when doing interface.encodeFunctionData
I have openzeppelin's standard ERC721 contract.
Below is the helper function that returns bytes data that will be used for some purpose.
async function getErc721SafeTransferFromTransaction(...
- 23
1
vote
1
answer
282
views
Encoding a bytes array with function signature: "TypeError: This type cannot be encoded."
I have a function in a smart contract I'm trying to call with call.
function doStuff(bytes[] calldata data) external payable {
To call it, I'm running:
bytes[] memory dataArray = new bytes[](1);
(...
- 10.2k
1
vote
1
answer
128
views
Expected primary expression in byte casting
I have a contract (Implementation.sol) which delegatecalls the other contract (Attacker.sol) to selfdestruct. When I try to compile the Implementation.sol on Remix, I receive Expected primary ...
- 13
0
votes
1
answer
66
views
Parameter function in Solidity
I am a newbie in Solidity. Below is the snippet of code I came across :-
pragma solidity ^0.4.0; contract C { //1
function f(uint len) { //...
- 43
0
votes
0
answers
533
views
Issue with abi.decode on output from reverted functions
I am struggling to figure out the abi.decode function when using it to decode the bytes coming as output from a reverted low level call to another contract. The way I am using it is by calling the ...
0
votes
1
answer
167
views
abi encoding with selector and additional variable
I am trying to abi encode a function abc(address, string)
the encoding looks like this
Address.delegateCall(abi.encodeWithSignature("abc(address,string)", _address, _string))
but I actually ...
1
vote
0
answers
35
views
Gas optimization: can I encode an array of different types into hex to pass it to contract call as bytes calldata instead of using memory or storage?
I'd want to have:
original types
--> encode them in bytes
--> string those bytes all together or as an array [[address, address], [uint, uint], [other_type, other_type],...]
--> convert to ...
- 21
1
vote
0
answers
245
views
How to split bytes from calldata and convert into memory variables?
Assume calldata for my smart contract being address as bytes, and few amounts as bytes chained together.
How can I extract the bytes for address and store it in
address memory address_ =
and the ...
- 21
0
votes
1
answer
47
views
Convert bytes to base 10 number by keeping digits in tact
I have a very weird use case. Tl;dr I'm trying to convert a bytes16 to a base 10 integer by keeping the digits in tact.
i.e 0x00000000000000000000000002987391 should become 2987391
- 516
0
votes
0
answers
15
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Is 1 word 4 bytes or 32 bytes in solidity? [duplicate]
I'm confused about the term word in solidity. When I google word, it says 1 word = 2 bytes but whenever I read word mentioned in the context of solidity, it sounds like 1 word = 32 bytes?
What is a ...
- 437
1
vote
1
answer
1k
views
Return bytes from inline assembly
I have two little tests in which I'm trying to return bytes that are populated via inline assembly. It works when I'm using a pre-defined return variable, but I'm getting a buffer overrun when I try ...
- 13
0
votes
1
answer
536
views
How to encode string as bytes array?
A similar question has been asked but using web3 in java, however, I would like to encode a string to bytes[] in solidity itself.
- 1,064
3
votes
2
answers
3k
views
Encode a struct with solidity
Is it possible to encode a struct in Solidity without serializing each variable separately?
Something like:
struct MyStruct {
uint x;
uint y;
}
MyStruct storage myStruct = MyStruct({
x: 11,
...
- 675
3
votes
1
answer
2k
views
How to pass bytes parameter to contract method call using Web3.js?
I'm trying to call a method in a contract and the method is like this:
function myMethod(uint8 tid, bytes calldata _bytes)
public
view
returns (string memory)
{ ... }
I'm using Web3.js to ...
- 31
6
votes
1
answer
3k
views
Convert/cast an address to uint256
Following these details on the values that make part of the calldata that goes into an L2 message in Arbitrum:
https://developer.offchainlabs.com/docs/arbos_formats#l2-messages
How do you convert/...
- 675
2
votes
2
answers
4k
views
Convert bytes to hexadecimal string in solidity
In a smart contract I have stored a bytes4 value: 0xa22cb465. I'd like to parse this value as a string:
string memory test = "0xa22cb465"
I've only stumbled upon explanations on how to ...
- 313
4
votes
4
answers
4k
views
Decode multicall bytes[] into readable format?
I created a Uniswap V3 pool using UI. In Transaction multicall(bytes[] data) function was called with this parameter:
[0]: 0000000000000000000000000000000000000000000000000000000000000020
[1]: ...
- 317
1
vote
1
answer
436
views
sload. with struct - loading bytes
I'm trying to load varios bytes from a struct in assembly. I found a good explanation here for uint. While this is working for uint and the whole memory slot i cant figure out how to get a bytes1 or ...
0
votes
1
answer
509
views
How can i change the 5th and 6th byte from bytes8
Hi Guys , How can i change the 5th and 6th byte from this bytes8 0x3FcB875f"0000"ddC4,or just arrive at this solution where: last four bytes(of bytes8) are this way 0x********"0000ddC4&...
- 318
2
votes
1
answer
386
views
Solidity (find a word in a string and replace it)
I am learning solidity string/byte manipulation and I am trying to create a Solidity function that finds specific words in a string/format and replaces them with given variables to return "edited&...
- 2,144
1
vote
1
answer
1k
views
How does Bytes-Utils slice function work?
I'm quite confused of how the bytes-utils library's slice function. I have a few questions about how it works, especially about the code below. The full code can be found here.
Why is tempBytes ...
- 23
0
votes
1
answer
738
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EXTCODESIZE returning 32 for contract size less than 32
I'm currently completing the Ethernaut challenges, one of them is to deploy a small contract (runtime bytecode is 10 bytes long).
I'm running the tests on my local machine, and using Solidity to ...
- 87
0
votes
1
answer
3k
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How to send bytes data to contract with web3.py to decode
I'm doing a test and trying to send bytes data to a contract so it can parse, store in variables, and return a value.
Solidity code
pragma solidity 0.6.12;
contract testbyte {
function sendBytes(...
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0
votes
1
answer
118
views
Store addresses in bytes variable
I need help with storing a bytes value.
contract StoreBytes {
bytes public addresses;
function addMe() external {
// TODO Add msg.sender to addresses.
}
}
What I want is that msg....
- 683
0
votes
1
answer
58
views
Requiring a bytes32 mapping to be empty, why does my transaction fail?
I have a contract here: contract source code
It's a simple one that allows users to create new key:value mappings with bytes32 variables, as well as update the value of a key given that:
the key is ...
- 3