Questions tagged [calldata]
Questions about the "data" part in a transaction, which can be accessed by "msg.data". web3.eth.getTransaction calls this field "input".
109
questions
0
votes
0answers
15 views
Who is the msg.sender when a library makes a call()
I have a library that is making a call to an external address like this
externalAddress.call(callData)
This callData is calling a function of another contract that is utilizing the msg.sender value. ...
0
votes
1answer
28 views
How to convert in-memory static array to calldata static array?
I have a contract called Erc20Recover in which I have the following function:
pragma solidity >=0.8.0;
contract Erc20Recover {
function _setNonRecoverableTokens(IErc20[] calldata tokens) ...
0
votes
0answers
6 views
Getting a specific var of <class 'web3.datastructures.AttributeDict'>
I have this code that is printing out all the vars of the class; however, I am only interested in the "input" var. Is there an easy way to access this this "'input': '...
1
vote
1answer
17 views
Where are value-type function arguments stored in Solidity?
When we define a function, say test(uint256 val). I would presume val would be implicitly defined in memory. But what if we change the funtion visibility modifier, does that change the location of ...
0
votes
1answer
14 views
Data location memory or calldata [duplicate]
Can someone tell me how to solve this problem? I am not advanced and cannot figure it out.
1
vote
0answers
14 views
Function argument sizes and gas usage
Is there any penalty for the amount of data passed to a function? Asking because I see non-linear behavior in gas usage during testing when sending more than 31 items in the array.
struct Payment {
...
1
vote
1answer
178 views
How to instantiate a calldata array?
I know how to instantiate a memory array. Looks like this:
address[] memory users = new address[](1);
users[0] = address(0x0);
But I cannot create a calldata array in this same fashion. Any pointers?
1
vote
2answers
323 views
How does Uniswap allow a user to specify which tokens the user wants to swap in this low level function?
I'm looking at the function swap that allows a user to swap token0 for token1 from Uniswaps UniswapV2Pair contract - https://github.com/Uniswap/uniswap-v2-core/blob/master/contracts/UniswapV2Pair.sol.
...
0
votes
1answer
61 views
Logic in approveAndCall function for erc20 token deprecated & not working
I am following along with a older tutorial on making an ERC20 token in order to learn Solidity a little better.
Since the tutorial is old, I've had to change a lot of things so far to get it up to ...
0
votes
1answer
30 views
How to execute a transaction within a contract given to address, and calldata?
Let's say I've got a contract called MyContract. My contract has a function which receives calldata and an address for another contract, called OtherContract
I want to be able to take the calldata and ...
1
vote
1answer
43 views
Data location specification and bytes32
Why is data location not required to be specified for bytes32?
0
votes
1answer
89 views
Incorporate calldata inside smart contract
I'm currently trying to use the 1inch API documented here: https://docs.1inch.io/api/nodejs-web3-example
I would be interested in using the 1inch pathfinder api from a solidity smart contract to make ...
0
votes
1answer
28 views
Check if calldata contains string
I have a function that is called with some data - "SOMETHING".
function checker(address _from, uint _value, bytes calldata _data) external{
//HOW to check if _data contains "...
0
votes
0answers
74 views
how to pass fix size array via interface in solidity 0.4.25
I used the following code
interface test{
function testfunction(uint[20] memory P, uint[20] memory Q) external returns(uint,bool,uint);
}
It gives the error Location has to be calldata for external ...
1
vote
0answers
41 views
Error in signing a raw transaction javascript -- calling a contract + attaching some msg.value
Here, I am trying to call a function(embrace) on a smart contract on Ropsten that needs two parameters and msg.value of 0.01 ether. But it's showing up the error that the msg.value is not sufficient. ...
0
votes
1answer
12 views
Why did I get an error about using memory keyword in function getname?
// SPDX-License-Identifier: MIT
pragma solidity ^0.7.0;
contract s12 {
uint public age;
string public name;
bool rollno;
constructor() public {
rollno= false;
}
...
0
votes
1answer
114 views
Why does this call to DSProxy fail?
Take these two contracts, both deployed on Kovan and with the source code verified:
DSProxy: 0xa92Bed719071A4d33B0B348513E7e866a6ff6B3F
TargetContract: 0xE3CD2e7a628b57d3e50c5f7B921182f676721bDF
And ...
0
votes
0answers
13 views
Creating several objects in the same transaction (data repetition)
I'm working with genetic algorithms and I need to create a population. Currently I have this function:
/// @notice Create a new individual
function createIndiv(uint _popSize) public{
for(uint i = ...
0
votes
1answer
300 views
Easiest way to call an implementation function from a proxy contract in Remix
I have the following code in my remix.ethereum.org project:
pragma solidity ^0.6.10;
// SPDX-License-Identifier: Unlicensed
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/...
0
votes
0answers
31 views
Proxy delegation contract doesn't work
I'm trying to make a proxy to make a contract that I can change for an ethereum project. I did what it says here: https://hackernoon.com/how-to-make-smart-contracts-upgradable-2612e771d5a2 but it ...
1
vote
1answer
524 views
Why does retrieving stored data cost so much compared to using calldata in Solidity?
I have a function that I need to pass an arbitrary length array of addresses to. In remix, just calling a function that has an address[] costs around 30k gas for an array of 5 addresses:
function fun(...
0
votes
1answer
80 views
Return multiple values from diferent smart Contracts
I have two contracts. The first contract has a function called get() that returns this values:
uint _value1
address _value2
address _value3
string memory _value4
string memory _value5
uint _value6
...
2
votes
1answer
74 views
Get return value of a low level call
I'd like to get the return value of a low level call.
(bool success, ) = address(0x1234...7890).call{value:0}(callData);
This post discusses a solution that sounds like it should work, but it doesn'...
0
votes
0answers
66 views
Is there a way to know if a Solidity method will revert?
I have some solidity methods in my contract, and when i make a send in web3.js i would like to know if there is a way to know if the functions are going to revert by using call.
Per-example , in ...
0
votes
1answer
174 views
Data location must be "calldata" for parameter in external function,
I'm getting the following error:
Data location must be "calldata" for parameter in external function, but "memory" was given.
for the following function:
function _registerAirline(address ...
0
votes
1answer
55 views
Error with this.balance
pragma solidity 0.5.9;
contract Testing{
function participate()public payable{
uint winner = 9;
require(msg.value == 0.1 ether);
if ( winner==9)
{
...
1
vote
2answers
43 views
When i call a function: Error: Returned error: VM Exception while processing transaction: invalid opcode
I work on Truffle. My contract is A and its function is infoRep(). infoRep() returns some data. Whenever i call the function in Truffle console the below error occurs:
Error: Returned error: VM ...
1
vote
2answers
133 views
Correct syntax for require required
I am getting following error message with require statement:
Error: Wrong argument count for function call: 0 arguments given but
expected 1. This function requires a single bytes argument. Use ""...
3
votes
2answers
726 views
How to generate calldata for a function
I have got as far as generating the method ID for the function:
function transfer(address src, address dst, uint256 amount);
The method ID would be:
bytes4(keccak256("transfer(address,address,...
2
votes
1answer
2k views
Why Remix IDE asks for CallData and what value we have to give? [duplicate]
In my several programs which I ran through remix IDE, I got a CallData text box. I don't know what value I have to give to this Calldata text box. I tried the following:
from: address : "...
3
votes
1answer
1k views
Remix IDE: What is the purpose of Calldata and Transact Tab
I am trying to execute the following code on Remix IDE.
pragma solidity ^0.5.4;
contract GuessTheNumberChallenge {
constructor() public payable {
require(msg.value == 1 ether);
}
...
0
votes
1answer
61 views
How to call function via interface from another contract when calldata type is used
I have declared the following interface:
interface Test {
function airDropMultiple(
address[] calldata recipients,
uint[] calldata tokenAmount
)
external
...
0
votes
2answers
42 views
Mining with additional data
i'm a beginner in using blockchain. Based on my knowledge, there are two ways blocks are created, mining and sending transactions. As there is an explanation to input additional data while sending a ...
0
votes
0answers
28 views
Call Type Explained [duplicate]
I have yet to come across a well explained definition of all the call types in one place.
* One of call
* Callcode
* Delegatecall
* Staticcall
Would be very grateful if someone could explain the ...
1
vote
1answer
482 views
What data is in 'calldataload'?
I want to parse event logs that are generated by the contract shown below, which assigns different sections of calldataload to the 4 Topics, and the Data section, of the event logs.
Topic 0 receives ...
49
votes
1answer
13k views
When should I use calldata and when should I use memory?
I have seen people use both memory and calldata keywords when writing Solidity. Specifically, they are used when declaring function parameters.
When should I use memory and when should I use calldata?...
0
votes
1answer
48 views
How to get the call graph of a mainchain transaction?
Simple question, but I couldn't find the answer.
There are transactions like this one which involve many chained contracts.
But as storage modify the functions being called and calldata doesn t ...
10
votes
1answer
2k views
What is a function selector?
I am reading an article, it says:
To enable deployment on the Ethereum platform, the contract functions
are compiled into EVM bytecode and a piece of code called function
selector is added, ...
0
votes
1answer
1k views
member not found or not visible after argument-dependent lookup in mapping
pragma solidity >=0.4.0 <0.7.0;
contract New{
mapping(address => string) public users;
string name;
address[] public userAddress ;
//string[] public userNames;
...
0
votes
0answers
50 views
Call Arguments? and Explicit call?
I am trying to understand the arguments of the built-in Solidity's (or EVM's: I am not sure) call function. I know it has 4 arguments. I am trying to understand the call function at:
Syntax Error in ...
1
vote
0answers
22 views
Calling private function from external - where are referenced type parameters stored in the end?
Let's assume we have something like:
contract C {
function externalFunction(uint256[] calldata data) external {
privateFunction(data);
}
function privateFunction(uint256[] memory data)...
0
votes
1answer
118 views
pass storage through interface to library
Here is what am i doing:
There is a library, accept storage argument as parameter, then do some math and return the result.
And there is a contract to call the function in the library, and an extra ...
0
votes
2answers
413 views
Unable to make a transaction with Data using Java api ethSendRawTransaction
I am trying to make a transaction between two different accounts using Java. It works perfectly fine as long as I am not using "Data" parameter.
My intent is not to call a smart contract but to make ...
2
votes
1answer
90 views
Understanding first evm word of reference types in assembly
Given the following function:
function getArrayItems(bytes calldata) external returns (
bytes4 _signature,
bytes32 _wutIsThis,
bytes32 _length,
bytes32 _firstItem
) {
assembly {
...
6
votes
1answer
910 views
can anyone help to explain calldataload
In the Solidity documentation, the definition of calldataload is:
calldataload(p) call data starting from position p (32 bytes)
But I am really confused by what is call data. Is the call data of ...
1
vote
0answers
276 views
Proxy contract DELEGATECALL to pass a DYNAMIC array to a function in the target contract
I'm trying to get a Proxy contract to correctly do a delegatecall to a function in another 'target' contract. The problem is, that I need to pass a dynamic array as the parameter to this function.
Q: ...
1
vote
3answers
723 views
Calldata with too many parameters
While reading https://solidity.readthedocs.io/en/v0.4.21/abi-spec.html#abi I was just thinking what happens when calldata contains more parameters/data than the function expects (I know first ...
1
vote
0answers
280 views
How to decode Tx data? Online tool?
Is there a fast way to decode the data returning from a Smart Contract call? I know there are github projects with JS libraries to decode this kind of data (such as https://github.com/ConsenSys/abi-...
asked Jan 23 '19 at 9:28
Juan Ignacio Pérez Sacristán
3,0327 gold badges34 silver badges64 bronze badges
0
votes
1answer
998 views
What is Calldata tag needed when a function has a string parameter?
I'm using:
pragma solidity ^0.5.0;
I have a function as below in my contract:
function test(string a) external{
a="apple";
}
An error shows up saying I need to add "calldata" to the parameter. ...
1
vote
1answer
1k views
Get the input data of a transaction with web3j
How can I retrieve transaction details (including the input data) from a txHash using Web3j?
I tried the following method:
public void buscarHhash(Web3j web3, String txHash) throws IOException {
...
