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Questions tagged [blockchain]

The Ethereum blockchain is a distributed database based on the Ethereum whitepaper specification and stores both the full transaction list and the most recent state.

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Is using private key of an account is legal or a good idea in your code?

I was using Nethereum for one of my application, there I found I have to sign transaction before calling a smart contract method, which was OK. I was using infura api. When I was calling ...
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I get a Memory Error on geth command

I need help. I ran this command on gitbash ./geth --datadir node1 --mine --miner.threads 1 I keep having this error message: Failed to generate mapped ethash dataset epoch=0 err="MapViewOfFile: ...
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1answer
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Retrieving the original message from an ETH transaction

When someone is simply sending ETH from one address to another, and assuming that person does not include a custom message in the transaction, then what exactly is the message that is sent on the ...
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Unable to connect to polygon mumbai test network using truffle

I'm trying to use Polygon test network with truffle and I followed this document and youtube video to configure Polygon network for truffle. But when I'm trying to execute truffle deploy --network ...
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2answers
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What happens to transactional data should a blockchain be missing a block, and would it be resolved?

Let's say a simple Ethereum blockchain consists of ten blocks which is distributed across 10 network nodes. Now, for whatever reason, an error has occurred which has enabled all nodes to agree that ...
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Unable to addLiquidity from pancakeSwap fork

I have forked pancakeSwap core and periphery and successfully migrated them on bscTestnet. I have also retrieved the init has code from factory and replaced it on router library. When i tried to call ...
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How to retrieve data from filecoin?

I want to retrieve or watch the video info after I upload it to filecoin. This is the step I followed. Or is there any better way to only watch the video info(ex:video title)? 1.I have uploaded the ...
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Getting error Error: Returned error: execution reverted on web3 [closed]

require("dotenv").config() const { ChainId, Token, TokenAmount, Pair, Trade, TradeType,Route ,Percent, WETH} = require('@uniswap/sdk'); var Fetcher = require('@uniswap/sdk'); const express = ...
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arguments to solidity function with html error

getting the above issue, here is my solidty code for the mentioned function function dividendTokenBalanceOf(address account) public view returns (uint256) { return dividendTracker.balanceOf(...
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1answer
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Creating complex transaction

I need help with understanding how this transaction was created. Link: https://bscscan.com/tx/0x02fa7264da976f01138b452b737350e4382e54fa60ee8b68b23b2efabb43c54a How it is possible to make a ...
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How to add a custom opcode in go-ethereum which support running an executable from the local ethereum node? [closed]

I have looked into the custom addition of opcodes Adding new custom opcode to solidity but I wanted some opcodes which can help me access the files. Any help will be appreciated, Thanking you in ...
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How to view staking rewards on blockchain? (Pancake Swap)

I recently staked CAKE in Pancake Swap's CAKE auto-compounding SYRUP pool. I get regular, auto-compounding rewards. No problem here. However, I need to see the individual transactions (i.e. have a ...
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How to Generate Buffer for Private Key

I am a beginner in Ethereum development. I am using Web3 js 1.0 to build a simple node js application that sends ether from one wallet to another on Mainnet. I am having problem in creating buffer ...
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2answers
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web3 multiple swaps within one block

I created a scrip that executes a swap/ transaction. However, I want to perform multiple swaps within the same block. E.g. 1 trade with 0.1 ETH and another trade with 0.2 ETH The above script executes ...
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1answer
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Why we sort tokens in uniswap functions?

function sortTokens(address tokenA, address tokenB) internal pure returns (address token0, address token1) { require(tokenA != tokenB, 'UniswapV2Library: IDENTICAL_ADDRESSES'); (token0, token1)...
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1answer
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WalletConnect web3 provider issue with TrustWallet (Multi-coin wallet)

I am using walletconnect/web3-provider to try to connect to trustwallet ios APP. My config on walletconnect is listed below: try { console.log("Log in with connect wallet") const ...
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How do farming/staking platforms really profit? [closed]

Sorry if this question isn't directly related to Ethereum, but to DeFi in general. I understand how we, users of platforms like PancakeSwap, Aave, Curve and such, can profit from these platforms when ...
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1answer
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Is there a decentralized way to intercommunicate between two Ethereum networks?

If I have Contract A deployed to the Rinkeby Test Netwok If I have Contract B deployed to the Kovan Test Netwok Then, can we program the contracts to interact with each other like Contract A invoking ...
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1answer
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Interact with Blockchain data

I'm new to blockchain dev (not dev in general), and I'd like to interact with the blockchains, is there a general API that I can call and for example if my wallet has 3 BNB and 3 ETH I can call that ...
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Get “unsupported protocol scheme” - Error occuring while triggering the TestClient smart contract

I am trying to setup Chainlink Node locally & deployed the smart contract onto testnet(Apothem - Xinfin Blockchain). All went fine, until I trigger the function to requestVolumeData(). #1) Job is ...
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Smart Contract is Minting - Help Needed

My smart contract is minting without a mint function. My smart contract can be seen here: https://bscscan.com/address/0xacd6fd33553b8dbb7efbc8ea3a1be09fa3650787#code It's meant to have a manual burn, ...
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1answer
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Will the ethereum blockchain have a problem with the timestamp in 2038?

I am reading that Ethereum EVM run over 32bits systems In base to this information: https://en.wikipedia.org/wiki/Year_2038_problem Will the ethereum blockchain have a problem with the timestamp in ...
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How can do use web3.eth.Contract()?

I am using web3 version 1.3.6. But some people said it can use version 0.20.1. If I use 0.20.1, I can not use other functions. Other Method?
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2answers
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Which transaction comes first in a block?

I'm calculating a wallet balance and just want to confirm transaction ordering. Is transactionIndex a reliable indication of which transaction came first? Is transactionIndex = 1 executed before ...
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1answer
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Blocks storage compatibility among different Ethereum Clients

Does anyone know if there are differences among the file generated to store the blocks by different Ethereum clients? I imagined that this answer is different depending on the consensus algorithm, ...
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0answers
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Tronscan transactions python3

I try get transaction on tronscan. from tronapi import Tron from tronapi import HttpProvider full_node = HttpProvider('https://api.trongrid.io') solidity_node = HttpProvider('https://api.trongrid.io')...
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1answer
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Can ERC tokens change their creation code or parameters afterwards?

Probably a dead stupid question, but just to make sure: can ERC20 or other tokens based on Ethereum Smart Contracts alter their properties after the creation? For example, can they change decimals ...
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1answer
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Dapp with frontend

I made a login page with metamask for my Dapp, but now I need to link my login button to the profile page which will have student details like name, phonenumber, certificates (pdf) etc. where these ...
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I am unable to deposit into a contract address deployed programmatically

I am new to smart contract development, please what am I doing wrong in my code? I have two smart contract (A and B) contract A is to be deployed by Contract B so that each transactions will have a ...
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1answer
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How to sign transaction from frontend with metamask and then send that signed data to rest api for submitting the transaction?

I have a front end connected with metamask wallet and a rest API layer. My requirement is to sign the transaction from metamask and then to send the signed transaction to rest api to submit the ...
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1answer
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ETH1 balances transition to ETH2

Can someone please explain how do the ETH1 balances become ETH2 if they don't move on-chain? How does eth1 become a shard? Is ETH2 an airdrop of eth1 balances?
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1answer
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Ethereum What is node?

I'm studying & developing Ethereum Platform There are approximately 5000 node servers in ethereum main net. Is it true that data is saved in one of node server(block) and share it with other node ...
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2answers
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Can there be two blocks with the same number?

I am trying to index blockchain data and I am thinking of what's a unique way to identify a block. Is it enough to use block number as the primary identifier and is there a possibility that the data ...
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2answers
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Ethereum Transaction Confirmations - how many are enough?

Is there a recommendation - or even some sort of unofficial "standard" - regarding how many Confirmations we should wait for before considering a Transaction successful/valid - and then ...
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1answer
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How to get token info with contract address in Ethereum

I use web3 library to interact with Ethereum Network and I want to get token info with his contract address such as tokenName, tokenSymbol, tokenDecimal, tokenLogoURL etc. I can get almost any data ...
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1answer
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Do contract size increase with gas in block?

I'm trying to deploy a contract with REMIX but it throw an error "smart contract too large, not enough gas". Is REMIX hardcoded for contract size ? Do smart contract size increase with ...
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0answers
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Query ethereum from C++

I was wondering if its possible (essentially if there exists a library) to query a node (either IPC or RPC) on ethereum. For example there is web3(py,js), there is ethereum in golang and probably ...
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Need help understanding whats happening in transactionhash details

Can someone explain to me what exactly is happening here? https://etherscan.io/tx/0x8f3e1ae0c440eef8d7f298dec5d5e7f707b961a606b87907e0b5cd71bde92c19 I want to track token transfers from a list of ...
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1answer
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How to build a decentralized bridge between two blockchains?

I am trying to build my own custom bridge between Ethereum and Binance Smart Chain so that people can transfer tokens and possibly some other assets from one chain to another and vice versa. For this ...
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WETH solidity smart contract for use as address in other contract

In the constructor of the Solidity contract given in the link below https://github.com/pancakeswap/pancake-swap-periphery/blob/master/contracts/PancakeRouter.sol receives a second arg which is address ...
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Reentrancy Attack

I need some help, Is this code susceptible to a reentrancy attack ? function withdraw(address to, uint256 amountOfEth) external override onlyOwner { require(_balances[to].shares >= amountOfEth, ...
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Cannot import 'VRFConsumer', 'PriceFeed', 'APIConsumer', and 'interface'

I'm new to brownie ( but not new to python) and am trying to get a basic project running to make sure everything works. I've been going off the Patrick Collins tutorial where uses the chainlink mix. ...
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Web3 - Having problems getting address of account

I have a web provider class const Web3 = require('web3'); const web3Provider = new Web3.providers.HttpProvider('http://localhost:7545'); const web3 = new Web3(web3Provider); class Web3Provider { ...
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1answer
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Contract constructor parameter which is also a contract

I have contract in solidity MasterChef.sol which can be seen at the link below https://github.com/pancakeswap/pancake-farm/tree/master/contracts I want to deploy it using truffle on the Binance smart ...
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1answer
358 views

Error on pancakeswap, web3 python

I try send transaction but i get error. https://bscscan.com/tx/0x3e716bc5d0500e8284de39c809a0251d07b0b3648591bf09fbafbb4dea633a34 I use web3.py tx_params = { 'from': wallet, '...
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1answer
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How to see events in Remix

I deployed a sol file in the remix,where can i find the event? please help me... pragma solidity >=0.7.0 <0.8.0; contract con1{ uint public x; event e1 (uint); function f()public{ x=5; ...
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1answer
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How are all these crypto tokens ICO's legal?

I started noticing lately a lot of crypto meme tokens being generated and sold online in a variety of ways. Basically everyone can generate ERC20 BNB based tokens, sell them in a pre-sale, and put ...
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1answer
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Conditional Transactions in Ethereum

Is it possible to send conditional transactions in ethereum? For, e.g., Alice wants to send five ethers to bob. Alice has initiated a transaction for this transfer, but these five ethers will be ...
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55 views

ETH smart contract deposit and withdrawal functionality - multiple addresses?

I have an ERC721 smart contract with basic functionality. When the user deposits this ERC721 token, I generate for him a new eth address. For example using account_pass = random_text() Account....
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How much does it cost to send all tokens to a liquidity pool?

I'm creating a token, and will create a liquidity pool on pancakeswap with a BNB pairing. If I have 20 billion tokens, and send them all to the pool with a price of $0.0000001/token. How much would it ...

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