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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Im trying to build a cryptocurrency(USD tether just like USD) that works with ethereum and polygon,
I happen to be relatively new to block chain, have an understanding of PoW and PoS, I'm learning Solidity at the moment, I'm supposed to design thi cryptocurrency that is compatible with ethereum and ...
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Not able to fetch correct APY in aave mumbai
I am following this doc - APY and APR - Developers to fetch lending and borrowing rates in mumbai for usdc but they doesn’t seem to be correct and are different from aave staging UI, how can I solve ...
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Solidity - Function Selector Loading onto the stack: why DIV instead of SHR?
I'm currently learning about how the function selector is loaded from calldata. The algorithm is like so:
PUSH4 ffffffff
PUSH29 0100000000000000000000000000000000000000000000000000000000000000
PUSH1 ...
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Foundry console.log and emit logs not working!
Running forge test -vv does not show the logs, but only test passed. Only forge test -vvvv `shows the traces, which shows the logs.
pragma solidity 0.8.20;
contract Testing is Test {
function ...
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Calling Uniswap Multihop Function returns Error
Deployed on Polygon Mumbai. Code compiles fine on REMIX and is meant to perform multihop swaps on Polygon Mumbai, but it returns error after function is called.
Deployed Contract always funded with ...
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Adding Uniswap interface to a ERC20 token smart contract
I just started learning Solidity, as browse through various smart contracts for tokens listen on Uniswap, I notice that most of them use IUniswapV2Factory and IUniswapV2Router02 and a small amount don'...
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Cannot import correctly uniswap's permit2
Hello i am trying to import the permit2 following the official uniswap's guide but i cannot manage to import it correctly since it lacks of the structs and more things even if i don't get any error ...
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The function runs external, but not internal
mapping(string => mapping(uint256 => Order[])) buyOrders;
mapping(string => mapping(uint256 => Order[])) sellOrders;
function placeBuyOrder(string memory stockName, uint256 price, uint32 ...
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USdt ERC20 1006
I am confused about this "Usdt erc20 1006" . In a website for withdrawal it is written "your Usdt Erc20 1006"..
This is certainly address but which type of address is this.
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ERC20 Multisend works on Sepolia Testnet but Fails on Mainnet
I've got a smart contract function that takes an erc20 contract address, an array of addresses and an array of amounts and then sends the each amount to each address of the specified token. I've got ...
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Redeploy safe with same address on OP
I deployed the Safe on Ethereum using this factory: 0xa6B71E26C5e0845f74c812102Ca7114b6a896AB2. Now, I'd like to deploy the same Safe address on Optimism. Could you please provide guidance on the ...
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Brownie Request for Random number (Mock VRF) reverts
Using chainlink tutorial and concept for testing a random request locally, Request Randomness fails to execute in brownie for VRFCoordinatorV2Mock, however, I tested the same code in remix IDE and it ...
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Solidity assembly: `target_slot`. Is it an opcode or other stuff?
I found this strange variable or opcode in inline assembly, but I'm not sure: target_ slot. I couldn't find its definition in the contract. I prefer it to be an opcode, but I didn't seem to find it ...
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How to Import OpenZeppelin Contracts with Node.js Environment
I'm having an issue. I'm attempting to compile my contract with Node.js inside of a VSCode terminal, but my openzeppelin imports aren't being seen, and I'm not sure how to handle them with Node.js. ...
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Rebasing tokenomics
I have the following variables where all values are multiplied by 1e18 to represent fixed-point numbers on the EVM:
uint totalShares = 100;
uint sharesAlice = 20;
uint sharesBob = 30;
uint ...
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How works refund ReentrancyGuard library for solidity
When I was reading the library code, I came across the following comment: "the values being non-zero value makes deployment a bit more expensive, but in exchange the refund on every call to ...
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Creating a token for my personal dapp use only
I want to store the money in a smart contract from my user as long the user wants and pay back the user once he asks i will not charge for this service
if I store ether in it and the value of Ethereum ...
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GoFundMe Contract: Minting "Thanks" over time vs all at once & "Thanks" token value
I was assigned to write a smart contract for class (to be deployed on a test-net), which, upon receiving ETH, returns to the sender some amount of tokens with symbol "Thanks". I want this ...
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What's the cheapest way to store a large amount of data into a smart contract?
I'm working on a smart contract in which we need to store some addresses along with their pending rewards periodically,
so the most first approach is to have a mapping of addresses to an int, like ...
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Foundry or Hardhat: I'm really confused about which one should I use?
Hello everyone
I'm new in the smart contract and Dapp development and I'm so confused about choosing a framework. my questions are dumb but I couldn't find the answers by myself. Here is my problem:
I ...
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Staking pool for native coins
I wanna build a staking pool for native coins like trx to test my skills as an engineer and yet due to my limited knowledge I don't know how to make a staking platform without creating a new token. Is ...
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Verify signature from dApp on contract
I am creating a signed message using a user address, nonce and number (amount of eth to send) like this:
const ammount = 1;
const userAddr = await otherAccount.address
const nonce = ...
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How can a bytes32[] variable have a custom method (i.e., verifyCalldata)?
Code: https://www.contractreader.io/contract/mainnet/0x0C7D4bdA40CF78F9F1BAf6e3D5774f1E22c9CC4B
My question is about this verifyCalldata() call:
function verifyAddress(
uint256 _projectId,
...
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removeLiquidity function in a smart contract, getting execution reverted due to ds-math-sub-underflow
i'm trying to create a smart contract which removes user's lp share from the pool doing these steps:
calculates the current user's balance of LP tokens for a particular pair
removes their liquidity ...
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What is the reason for this assembly code?
I am looking at the following contract, specifically the following assembly code....I think I decoded that it means make sure that if the contents of slot 0 equals 2, then store 3980109478 (which is ...
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What is the purpose of the import statement in Solidity?
Could someone explain to me what the pupose of the import statement is, in Solidity? Is it the similar to inheriting from another contract where you have access to the state variables and function of ...
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Chainlink fulfillRequest is not able to call another contract
I am working on a project that includes Chainlink Functions (for off-chain API calls) and CCIP (to transfer tokens cross-chain).
My project includes 3 main contracts:
FunctionConsumer.sol: Chainlink ...
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gas estimation error because of reverted
here is a situation I have: a user came to my platform to buy mytoken and he paid 44 matic for it and 266,087 | 263,663 (99.09%) which reverted because of the gas out. is there any solution to add gas ...
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Are multiplications after division UNSAFE?
I have a smart contract which essentially does this:
uint256 tokenRate = _pair.a2 * PRECISION_FACTOR / _pair.a1;
uint256 toSend = _amount * tokenRate / PRECISION_FACTOR;
uint256 feeToOwner2 = toSend ...
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How can I get a defi site source code?
I'm trying to expose a defi scam website which copycats a famous platform on TRX blockchain. I have their transaction address, but no source code or website's contract address. I was wondering if ...
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Assembly 'create2' and 'new' with salt not determining the same address
Since solidity 0.8.0, we can now specify the salt for contract creation using new keyword
Using 'new'
bytes32 _salt = bytes32("0x4");
address addr = address(new DummyContract{salt: _salt}());...
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Why are you able to swap eth to token lesser than specified amount in amountOutMinimum?
I am using Dai as an example for token address in constructor so when you call this function it should swap ether to Dai.
My question is why sending ether lesser than amountOutMinimum. It still able ...
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Swap functions seems to not swap?
I have deployed a smart contract on a local network and I am trying to do swaps from a metamask account. I have allocated a quantity of tokens to the smart contract so it can use it using the approve ...
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Whats in the mempool? Was wondering if there are listed properties that anyone can view it
If you send a transaction and it is in the mempool, what are the properties in the transaction of the memool?
I was wondering if you can get the address of the sender in the mempool. What else can be ...
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Inline assembly loop doesn't update memory
I want to copy in inline assembly from calldata the last two bytes of every 32 byte slices to the lower half of the first free memory slot(32 bytes).
free = free memory pointer + 14 (bytes)
moffset = ...
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Trying to create a soulbound token. Keep getting two errors
I'm trying to create a soulbound (non-transferable NFT) token on Solidity. Here is my code so far.
// SPDX-License-Identifier: MIT
pragma solidity >=0.4.17 <0.9.0;
import "@openzeppelin/...
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How can I fetch the current dollar price of BNB in a Solidity smart contract?
How can I fetch the current dollar price of BNB in a Solidity smart contract? Are there any recommended APIs or secure, decentralized methodologies for this?Is there a way to fetch the dollar price ...
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How do you deal with relative imports in a contract you depend on?
Goal
I am attempting to create a smart contract that uses contracts from the iden3 library. I am using the Remix IDE.
Problem
My issue is that the contract I need (IdentityBase.sol) has several ...
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How to I solve fetch has been blocked by CORS policy when fetch data from contract
I'm trying to fetch campaign data and display it to the user. I'm using Nextjs in the front-end and solidity & hardhat in the back-end. The contract data seems to be fetched but when being ...
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Bought a scam token, trying to understand what part of the code should I check next time to prevent that
Contract code - https://etherscan.io/token/0x67bcd18a484a88f073097a18b0462eb7c44d3178#code
Ownership renounce at 08:17 UTC https://etherscan.io/tx/...
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Decoding Chainlink Function Response in Solidity Contract and Handling Nested JSON Objects
I'm dealing with a problem regarding the decoding of data obtained from a Chainlink function in my Solidity code. Specifically, I'm using a Chainlink custom function that sends an HTTP GET request to ...
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Trying to issue ERC 3475 tokens
I'm trying to issue ERC 3475 tokens from a relatively simple contract using Remix. The contract compiles and deploys when gas is optimized, but when I try to issue the tokens I get an error of "...
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Kill a smart contract where my funds are currently stuck inside
I am the owner of the contract however I didnt write it but have some funds stuck inside, when i try to withdraw or run the contract the remix IDE tells me that "Gas estimation errored with the ...
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Reliably disassamble bytecode to opcodes across various evm versions
Is there a reliable way of disassembling bytecode into opcodes across different EVM versions, to make it agnostic to the EVM version used during compilation?
As the second best option - is there a ...
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Invalid implicit conversion from enum to enum
My question is how is it possible to have such error:
Error (9553): Invalid type for argument in function call. Invalid implicit conversion from enum CoinType to enum CoinType requested.
--> test/...
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How do old smart contracts that contain certain opcodes behave when those opcodes get deprecated/removed in hard fork upgrades?
For example say a contract with a compiler version of 0.7.5 (pragma solidity 0.7.5) contained selfdestruct(payable(address))
what happens to the contract when the self destruct opcode gets deprecated ...
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How to pass blockNumber to viem call?
I'm trying to view the owner of a certain NFT at a specific blockNumber, when I make the viem call without the blockNumber parameter it works perfectly, however, once I try to pass a blockNumber with ...
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I want to call a contract method using my safe wallet address
I made a safe wallet in my panel safe wallet which is 2/3 signers. I want to use it in my access control for an admin role and use it for calling a transfer method with it only. The problem is when I ...
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Object has no member 'call' when reading smart contract in geth console
I'm following the Storage contract example from the Geth site (https://geth.ethereum.org/docs/interacting-with-geth/javascript-console-contracts)
I am unable to call a 'retrieve' function on the ...
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How to exchange one nft for another from a different contract?
I have 2 ERC1155 contracts, and am looking to transfer nft2 into nft1's wallet upon checking wallet holds nft1, but not sure what I'm doing wrong.
This is my nft1 contract:
import "./NFT2.sol&...
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