Questions tagged [solidity]
Solidity is a contract-oriented, high-level language whose syntax is similar to that of JavaScript and it is designed for writing smart contracts in Ethereum to run on the EVM. Solidity is statically typed, supports inheritance, libraries and complex user-defined types among other features.
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Solidity query works in dev environment but not in production build (nextJS)
I am calling a function that queries the token balance of a user. The query works on a dev environment but not in production build. I am using metamask and ethers to interact with my contract on the ...
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Has the way to access public member variables in solidity through deployed contracts changed?
I have a public contract member defined like this, which is later assigned a value in the constructor
AggregatorV3Interface public priceFeed;
I want to access this variable's value and I am trying ...
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Missing transaction details in MetaMask (only showing gas fees) dApp testing
I'm building a presale dApp as an experiment, and when I hit the buyButton, MetaMask successfully opens for me to approve spending my USDT (labelled a contract interaction). However the transaction is ...
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Can we override the private variable in base contract?
Background:
I'm using an opezeppellin Erc20 contract. but i want to use it for minimal proxy pattern(eip-1167).
so for that reason i cannot use constructor and have to use the initialize method. Now I'...
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Cannot recover signer
I am facing a problem where recoveredAddress is not restored correctly. We assume that the address of the owner who originally deployed the smart contract is returned. Am I making some big mistake? ...
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Use offchain date time
in my contract, I need to do something based on time, and this is quite sensitive, and as we know, you cannot rely on the block.timestamp because it can be changed, I want to know if there is a way ...
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I want to check seller balance before trancsaction and after tracsaction and check them if they are equal or not
I created an auction exchange smart contract using solidity programming language and this is a test file written in JavaScript. seller is the creator of auction and buyer1 and buyer2 are the persons ...
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How to use anvil accounts in the Foundry Test
How can i use anvil accounts into the foundry tests? Like in hardhat node i can getNamedAccounts() but how can I use the anvil accounts into my forge Tests?
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Remove the element from array where order matters?
I am presenting my use case here. Let's think of a dating app where each candidate enters their preferences and we store their data and add them to an array. when someone enters that matches with any ...
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How to import external files?
I'm trying to create a fund function that allows users to fund their wallet after signing. I had my contract address & ABI stored in an external file and tried to export and import, but that didn'...
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How can I verify & publish source code on bscscan?
Can someone please help me verify & publish the source code for this token?
I keep getting error message saying invalid constructor arguments (please make sure they are in ABI encoded format).
...
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How to find a variable declaration in an AST object
I'm using Javascript, and I have a Solidity AST object.
Is there a library or an example out there to easily find if a text string (variable/function/mapping/struct etc declaration) exists and return ...
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How can I fix a problem with transferring ERC721 by approved contract?
Hey everyone
I'm new to NFT development and developing an ERC721 token for property ownership and marketplace. I implemented two functions to enable a user to put their token on sale for another user ...
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How do you use the Diamond Pattern for escrow upgrades?
I am creating a contract with the diamond pattern so I can evolve and add new features to my contract.
Contract facets:
Contract A: an ERC721 that takes care of minting its own NFTs
Contract B: ...
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Why or where should one use Twos Compliment in Solidity?
I was reading through Solidity Docs and came across Bit Operations section
https://docs.soliditylang.org/en/v0.8.21/types.html#bit-operations
Couldn't figure out why one would use this.
However, I do ...
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Do you have to explicitly state in the body of a function that it should return something?
I'm looking at the following function which is supposed to return (uint8 id, uint8 nextId). I see that in the body of the function, the return statement is within an "else" statement - see ...
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ERC721 token image not showing in wallet
Hey everyone
I'm new to NFT development. I developed an ERC-721 token used for property ownership and I deployed and minted a token both on Anvil and sepolia. I can import the token on metamask but ...
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how come loading the funcSig from data isn't enough, you have to shift it also to use it in the rest of the code/function
basically we have this function
function FlaggedMethods(
bytes memory data
) public returns (address) {
bytes4 funcSig;
assembly {
// Shift right by 224 bits ...
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Instantiation of Solidity Interfaces
There is an interface called IiZiSwapFactory (source), which declares a method named swapX2YModule() (source).
IiZiSwapFactory.sol
interface IiZiSwapFactory {
/// @notice emit when successfuly ...
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approve spender to swap
i'm trying to swap using 1inch aggregator api and when i try to swap, it says
"Not enough allowance. Amount: 4600000000000000. Allowance: 0. Spender: 0x1111111254eeb25477b68fb85ed929f73a960582&...
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Creating a local variable in an if statement?
I'm looking at a function that creates a local variable in an if statement. If someone called that function and the condition to the if statement was not triggered, that local variable wouldn't exist, ...
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Explain this constructor inheritance solidity
Is BranchBridgeAgentFactory the parent contract?
Will there be two different address? Or just one?
pragma solidity ^0.8.0;
contract TestBranchBridgeAgentFactory is BranchBridgeAgentFactory {
/*////...
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NFT metadata for property ownership ERC721 token
Hey everyone
I'm new to NFT development and I'm trying to develop a simple property ownership and marketplace using the ERC721 token standard. since I'm so unfamiliar with json I have some problems ...
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provide steps to deploy this contract from solidity by example
When i tried deploying this contract using 10 ethers, and then providing :
claimPayment()
-> amount - 9000000000000000000 i.e 9 ethers
-> nonce - 123
-> signature - ...
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Is there any way to read block attestation from inside a solidity smart contract?
Are there any precompiles, or any other native ways to get block attestation data from ETH2 POS inside a solidity contract?
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How do I hide or mask the sending address when sending tokens or eth
I am trying to build a crypto payment gateway. But when users initiate a withdrawal to credit their customers, the transaction can be tracked up to the point that shows the system address where the ...
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Failing deposit transaction
The following deposit transaction on Mumbai test net is failing as opposed to this transaction on Polygon main net which had succeeded years ago. There are no fundamental differences from code or ...
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How to extract the custom reverted message inside the transaction object when we're using solidity error keyword?
// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.4;
error Unauthorized();
contract VendingMachine {
address payable owner = payable(msg.sender);
function withdraw() public {
...
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eth_call vs eth_sendTransaction
During my development process, I've spotted differences between calling function in my contract from script and from dApp. Whole thing is done on hardhat local network.
Script call:
eth_call
...
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are there other ways to send bundle of transactions without using flashbot?
I am wondering if there are some ways to send bundle of transactions without using flashbot?
I am not sure how this area works,
would you please give me practical sources to learn ?
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org.web3j.protocol.exceptions.TransactionException: Transaction receipt was not generated after 600 seconds
Yesterday I could deploy the code successfully, but today onwards I am facing the below error. I tried to reduce/increase the gas fees yet the error is still not resolved.
If anyone is willing to ...
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Sending data to the contract from the react frontend is not working
I've made an twitter contract, where we can send and get tweets from the frontend React. While sending the data to the contract, The metamask popup is opening, But it shows warning like this.
I don't ...
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Tick range of negative tick - Uniswap v3
I am looking for a formula to calculate the tick range for a negative tick.
Ex1:
tick: -15
tickSpacing: 10
range: [-20, -10)
Ex2:
tick: -20
tickSpacing: 10
range: [-20, -10)
I was ...
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Getting Error in the code ParserError: Function, variable, struct or modifier declaration expected
pragma solidity >= 0.8.2 <0.9.0;
contract Types {
// Declaring a dynamic array
uint[] data;
uint8 j = 0;
function loop() public returns(uint[] memory){
while(j < 5) {
j++;
data.push(j);
}
...
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Signing message using web3 and using ethers gives different result. Why?
I'm encoding a message using ethers' solidityPackedKeccak256()
const encodedMessage = ethers.solidityPackedKeccak256(
["address", "uint256", "uint256"],
...
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UniswapV3 Quoter throws error: contract runner does not support sending transactions (operation="sendTransaction", code=UNSUPPORTED_OPERATION)
I am working with the Quoter from Uniswap V3, here is the part of the function that challenges me:
...
// Reformat Amount In
if (!isNaN(amtIn)) {amtIn = amtIn.toString()}
let amountIn = ethers....
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ERC721: invalid token ID"
I'm minting an NFT and listed it on my NFTMarketplace, after minting I keep getting ERC721: invalid token ID, whenever I try to create the sale on the market place.
this is my nft code
// SPDX-...
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Where to place special functions receive() & fallback()?
receive() external payable {
fund();
}
fallback() external payable {
fund();
I want to find out where exactly should these special functions be wrriten; should they come before the contract ...
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Is it possible to import foundry anvil in rust?
I successfully installed and used anvil from the wsl shell.
I have some rust code, where i want to import foundry anvil instead of running from shell, cause i want to be able to control it from the ...
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1
answer
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Where in the code of this unstake function is ETH actually transferred?
I am looking at this repo, which is contracts for a decentralized pegged asset issuance system backed by liquid staking tokens like rETH. Specifically, I have a question about the functions unstake in ...
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I need to use ‘selfdestruct’，How to prevent the implementation of eip-4758?
I found a very useful idea compared to the traditional deposit method on exchanges.
Using this method, not only does it not need to manage secret keys, any account can perform token collection, but it ...
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Unable to change the storage using Delegate call
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract Preservation {
// public library contracts
address public timeZone1Library;
address public timeZone2Library;
address public ...
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How to change the storage using Delegate call
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract Preservation {
// public library contracts
address public timeZone1Library;
address public timeZone2Library;
address public ...
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Treating two assets as equal in a smart contract that aren't equal
I am auditing a protocol that creates a token yETH representing a basket of liquid staking tokens such as rETH and stETH. I noticed that the protocol treats yETH as if it is 1:1 with ETH when it's ...
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Batch NFT mining
I am trying to create a project where users can specify a total supply on a minted NFT, will the NFT all have the same address but with different tokenId's or they will have different addresses
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How to give allowance to a contract and send erc20 between accounts
I wrote the following contract:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
contract enviaToken {
address public ...
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How the uint changes to address type in solidity when using delegatecall?
pragma solidity ^0.8.18;
contract One{
address public first;
address public second;
address public third;
function setaddress(address _address)public {
third = _address;
}...
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Create a new Erc20 contract through Ether.js
I've a functionality in my nextJs application to create an ERC20 token on a fly. Like user can input a contract name and symbol, and behind the scene through the Ether.js a new contract gets created ...
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Can you refer to a contract inside itself?
Sorry this is a very minor question but the following is part of a contract called LibOrders.sol. The function below calls LibOrders.cancelOrder....normally I think you would just put "...
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Can I edit in the msg.sender value for the called contract?
let's assume following solidity contracts:
contract EntryPointContract {
address one = '0x...';
address two = '0x...';
address delegateContract;
constructor(address ...
