All Questions

I want to create an ERC721 smart-contract. The token will be associated to a png file. The users will see there tokens in metamask and i want to display there png files in metamask (this is very ...

My contract has to take ETH as a collateral and send some stablecoins ( like USDC) to user. How can I use any stablecoin into my contract , assuming contract has an infinite supply of USDC ? I too ...

i tried to import my myetherwallet account into metamask by entering private key and try to connect both account but my imported account does not show any tokens i tried it many times by unistalling ...

Good Evening all, I have encountered a bit of a problem. Being fairly new to the whole crypto game, I went to withdraw some ERC-20 tokens from an exchange account of mine and sent them direct to a ...

I have read that it takes about 12 seconds for an ethereum block to be mined. Let’s us say I have a contract mined on block 100, can I set a function that can only be run at block 200 or more? Thus ...

I am trying to implement the following exercise "Santa's list": Build a system for tracking who is on their nice list and who is on their naughty list. Furthermore, I do not want duplicates ...

I have used the following request to estimate gas in an ETH transaction in Ropsten. ## JSON-RPC over HTTPS POST curl https://ropsten.infura.io/v3/YOUR-PROJECT-ID \ -X POST \ -H "Content-...

Not showing on binance 0xd76e92ca9f39656061a5d88a17fba884db2b188ed02e2e678a7c58b24dd109f9 - I found it on etherscan, anyway I can get it back ? many thanks

I have two questions. My contract has compiled and deployed successfully both using remix and truffle. However: q1) remix returns an empty array of ABI. Also, after I hit compile the contract at the ...

I have an up to date OpenEthereum node that is taking a long time to sync it's ancient blocks, Which has left it syncing a batch of ancient blocks, while falling behind, then syncing up to date. Put ...

I did a swap on uniswap and I lost my ether. The transaction failed. How do I recover my ether? Why does the transaction fails?

I am new to flash loans. Let us say I have smart contract where people vote. Your voting power on this contract is based on how many token x you have. The votes are yes and no and the vote with more ...

I transferred ETH token from Binance hot wallet to ETH wallet by mistake. How can I get that returned to Binance wallet. Can someone please help me on this. Regards

Here is the doc about provider in ethers 5.x document: new ethers.providers.JsonRpcProvider( [ urlOrConnectionInfo [ , networkish ] ] ) Connect to a JSON-RPC HTTP API using the URL or ConnectionInfo ...

Can I broadcast someone else signed transaction and use fee from my address? if yes then how? Let me elaborate my Question Suppose person A want to transfer some ERC tokens to person B. But person A ...

Transferred eth from bnb to crypto.com wallet, successful on block chain not reflecting in my wallet. TX ID: 0x768b065141910a5d225e187189433143aea9d792723536ffd87fd93247d8c484

After enabling JWT token authentication on besu network, a connectionInfo with JWT token in headers is used to make connection to the network, instead of url. import { ContractFactory, ethers } from &...

https://eips.ethereum.org/EIPS/eip-20 says this about the decimals() method for an ERC20 token: decimals Returns the number of decimals the token uses - e.g. 8, means to divide the token amount by ...

Recently a trader extracted significant profits from sandwich attackers with a contract called Salmonella. The contract modifies the standard transfer function to send only a fraction of the requested ...

ERC721 says that NFTs can only be transferred by owners/authorized addresses. How are solidity marketplace contracts made to allow a third party address to transfer an NFT from your account to theirs ...

My frontend code: html (using cdn, couldn't make the npm run...): <script src="https://cdn.jsdelivr.net/npm/web3@latest/dist/web3.min.js"></script> javascript: web3.eth.personal....

I am trying to understand the logs I see when I journalctl -fu my Geth service, which I restarted after it was offline for two days. This is less a troubleshooting question and more an extension to ...

I have a transaction hash (for example 0xd97a7f7e15709ce345842a52a6e8db395e6ba779fd76a426b1878512a34a8128) I would need the information in red, basically the tokens involved (the first one is an ERC20 ...

Since Solidity v0.8, the compiler has checks for {over,under}flow by default for all arithmetic operations. Do these checks apply to assembly (yul) arithmetic operations too?

As per Wikipedia, a find first algorithm is: a bit operation that, given an unsigned machine word, designates the index or position of the least significant bit set to one in the word counting from ...

could you please help me with this step? I have a smart contract with a constructor with a parameter, but I don't know how to pass this parameter when deploying the smart contract using truffle and ...

''' Document <link rel="stylesheet" type="text/css" href="main.css"> <script src="https://unpkg.com/web3@latest/dist/web3.min.js"&...

I have been trying all the solutions and tutorials I found on the Internet, with no success. Remix fails to compile vyper smart contracts in local and remote. How to make it work?

Yeah so I'm creating a eth token and I need to find a way that buyer have a purchasable maximum limit. Can anybody help me with that ? Can't find answer thanks a lot.

Kindly find the following results below from my Mac Terminal: miner.start(1) --> null miner.stop() --> null eth.getBalance(eth.accounts[0]) --> 350000000000000000000 eth.syncing --> ...

My tokens and basic setup scripts are built in solidity 0.8.0 and I just downloaded GSN with OpenZeppelin because I need a platform which will fund users' few things. Now I can't compile because it ...

I have create a project on infura.io website. I have create a new truffle project. Here is my truffle-config.js file: const path = require("path"); const HDWalletProvider = require("@...

I want to sign a message with my ethereum account in a javascript application. I do not want to work in a web-browser or with metamask. I want to build a stand alone javascript program. Is there a way ...

I am trying to get data from earlier blocks/transactions. I have created events and emitted them. I can see the logs in the Remix IDE. However, I cannot get the logs in web3.py. It only returns empty. ...

I want to understand how Ethereum works and i want to calculate the public key and wallet address from private key. I have read this tutorial: https://piyopiyo.medium.com/generating-an-ethereum-wallet-...

i have created a Smartcontract. now i want the functionality: where 2.5% of every transaction is transferred to a fixed address. say the address is 0x809341c1c1cba2d6accf8188bca463a119443d. i know it ...

I am trying to run a setter function (testCallBar) in Caller contract which should run setVal() of Receiver contract using call method. But it does not works. testCallFoo() works as expected but ...

I have create this test: const { expectEvent } = require('@openzeppelin/test-helpers'); const MyContract = artifacts.require('MyContract'); contract('MyContract', function (accounts) { const [...

Here is what i've done in a blank directory: $ truffle unbox react $ npm install @openzeppelin/contracts $ npm install @openzeppelin/test-helpers $ npm install @truffle/hdwallet-provider Then, i have ...

I'm have an expensive view function which calculates rewards over time and investment. When it comes to withdrawing rewards I would need to run this, which could overrun gas for the block. Is there a ...

I want to know if Ethereum stores the contract's deployer address by default. I know Ownable Library which stores owner's address in a storage variable. I want to know if Ethereum blockchain stores ...

When validating a block, do validators know who the other validators are, prior to voting? Does the proposer know the other validators prior to proposing a block? If so, that could lead to collusion ...

On bsc and also i would like to lock liquidity for 1 year aswell as other improvements etc Can anyone help me get a token stsrted.

I'm using web3js get transaction info on a specific ETH address. When I make the getTransactions call, no info is presented. I then check etherscan and also see that my binance ETH wallet (for ...

It's almost an exact copy of this but when I ran it, I get the following error message. (node:5189) UnhandledPromiseRejectionWarning: Error: Returned error: transaction underpriced Below is the code ...

I wondered what happens if for example OpenZeppelin changes the path of a contract I have imported like this: import "@openzeppelin/contracts/token/ERC721/ERC721.sol";? Will my contract ...

How to write a contract on uniswap router with etherscan API. I want to write a contract on the router as soon as a trigger function execute.

Consider the following contrived contract function: function submitOffer(uint256 foo) public payable { emit MyEvent(foo); // then later... require(foo > 10, "Foo must be greater ...

TL;DR: I have a method in a contract to calculate a keccak256 hash, and I'm trying to replicate it in Web3, but the hashes don't match. My problem is very similar to the one in this question, but the ...

I have been looking for almost 2 weeks but I can't find any use case for my implementation. I want to create an application for movies adding and rating using Ethereum and Solidity on local ...