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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TypeError: Indexed expression has to be a type, mapping or array (is function (address) view returns (uint256)) --> Untitleded.sol:39:17: | 39 | requi

Again i have a new question. this is the full erorr. TypeError: Indexed expression has to be a type, mapping or array (is function (address) view returns (uint256)) --> Untitleded.sol:39:17: | 39 | ...
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How to fractionalize ownership of a collection of NFTs across multiple investors?

An Ether wallet contains a large collection of ERC-721 NFTs. Normally only one owner knows the seed phrase for a wallet and therefore is the owner of all the NFTs inside the wallet. How can such a ...
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Throughput and Latency of Private Ethereum Network

How do I calculate Throughput and Latency of a private Ethereum network that I have set up locally on my computer? I tried the solution given in Measuring transaction latency and throughput in a multi ...
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Interacting with wrappers in contracts from Go

I'm currently having issues with contracts in a small project of mine. The issue is as follows: I have a Go client for a Dapp and some Smart Contracts to interact with. I planned a contract (...
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1answer
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Untitleded.sol:5:77: ParserError: Expected type name function sendmessage(string message) view public returns(string message, memory) { ^----^(i need)

I've seen the other StackExchange errors but it didn't help me. Untitleded.sol:5:77: ParserError: Expected type name function sendmessage(string message) view public returns(string message, memory) { ...
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Binance Smart Chain setup [closed]

I downloaded the project from Binance Smart Chain github account and when I say make all, I get the following error.
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How i can switch between account without using metamask

I import 10 accounts from ganache to metamask and I give each user's login to my application an address. i want to switch between this address without using metamask i want to change this address ...
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What are the factors involved in NFT gas consumption?

After reading this article ("The Unreasonable Ecological Cost of #CryptoArt" Part 1, Part 2), I'm keen to better understand what are the factors involved in energy consumption by NFTs. The ...
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Ensuring the atomicity of multiple transactions

I am new to solidity and have been creating single (both basic and complex) transactions. However, I have a question which I couldn't come up with a solution. How can I create 2 (or more) transactions ...
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1answer
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Ethereum Bucket Synchronisation

The normal operation of Ethereum and other blockchains is to Store new transactions in a mempool, Distribute the bucket, and then mine contents into a block picked from the bucket based on priority of ...
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What happen to the transaction that in the uncle block? [duplicate]

If a block realize it is an uncle block, what happen to the transaction that in the uncle block? Will the transaction in the uncle block be allocated into the transaction pool again or the sender need ...
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1answer
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Can one read the contents of a private variable in a contract outside the contract? [duplicate]

Can one view (externally) the contents of a private variable defined in a contract? Or, the only way one can view (externally) is by declaring the variable public or having an external function ...
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Error when call contract method on binance smart chain

when a i call any of contract methods (the contract is the pancakeswap factory), this error return error: call revert exception (method="allPairsLength()", errorSignature=null, errorArgs=[...
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If you are a miner can you accept your own transactions at no cost? [duplicate]

Let us say I am a miner. Can I accept my transactions into the blockchain at no fee to myself? And what do I lose? Let us assume someone is running a dapp. Can they mine transactions of that dapp to ...
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Do some crypto-assets have an “admin key” that allow some users to exercise “unilateral control and influence” over the asset?

I am reading the SEC prospectus Coinbase's initial public offering, available here. On page 20, it is written: Many crypto assets have concentrated ownership or an “admin key”, allowing a small group ...
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The Graph Compound API

I want to build a small project to simulate app.compound.finance (with just eth token let's say) with The Graph , how can I get supply/borrows balance per users? (my defi app initial setup is done, ...
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How to send erc20 tokens through web3 on nodejs

My transactions go through without errors, while they're pending the data field shows the amount of tokens I'm sending, but when the transaction goes through the data field is empty. Here is my code: ...
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Access old transaction from a web react dapp

I have create a dapp react app with this command: $ truffle unbox react I have a sample web application in src/client/ folder. This web application is able to communicate with Ethereum smart-contract ...
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Problem with BSC full node

I try install full node Binance Smart Chain (https://docs.binance.org/smart-chain/developer/fullnode.html). I follow all the instructions on the site. After the command geth --config ./config.toml --...
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What can smart contract creator of Token on Ethereum Platform do to modify, change, upgrade or screw everybody on a DeFi platform?

Let's say an anonymous creates a Token called "baked" with Total supply of 1 million, and he keeps only 10k, and I buy the rest 990,000 He then uploads the Token on Decentralized Exchanges ...
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1answer
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Web3 transaction execution is slow (5 secs)

I am trying to send a transaction to a contract through web3, with the following code: const c = new web3.eth.Contract(contractData.abi, address) console.log(new Date()) const x = await c.methods....
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How to sign a smart contract deployment transaction?

I have a question related to smart contract deployment and wallets. Since I am new to the Ethereum blockchain world, I want to get an insight on how it actually works and write down what a developer ...
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1answer
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Dapp using react-native and truffle

I have a blockchain dapp which is working fine in web browser. Wallet : Metamask OS : Ubuntu 20 Node : 10.19.0 Npm : 6.14.4 But, I would like to run the dapp in mobile view using truffle ...
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Is chain link a stand alone blockchain?

Is chain link a stand alone blockchain or is it a series of smart contracts on the ethereum blockchain?
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given tx hash: tokens transfered?

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 ...
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1answer
29 views

Can you potentially mine for anything?

This is more of a general "blockchain" question and not specific to Ethereum so if I'm off topic here I would appreciate it if you could direct me to a more relevant stackexchange maybe. On ...
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1answer
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Is each of metamask's account independent to each other?

Say I create 3 accounts with my metamask (same seed phrase), if one account is "compromised" by a website, will it also affect the 2 other accounts if I didn't give the website any ...
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How can a contract interact with other chains?

Reading the Waifusion postmortem article this caught my eye: At the same time, we were made aware of multiple parties that were going to fork us as soon as we went live with a sale on BSC. This has ...
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Oracle Price Feed Event-Based mechanism

As you know chainlink oracles work like callback functions. I have only one function is that payable one and I need to know the correct eth value in token parity. I cannot request data when the ...
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Retrieving the sender of a transaction

I am trying to retrieve the sender address within a transaction in Go and I am facing some issues. As I understand, in order to retrieve the sender of a transaction, you can either try to get the ...
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How much time does it take to withdraw from Optimistic Rollup?

I am reading An Incomplete Guide to Rollups and Vitalik says the withdraw time of Optimistic Rollup takes ~1 week (withdrawals need to be delayed to give time for someone to publish a fraud proof and ...
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1answer
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Holders and Max Supply not updating on Ropsten Etherscan

I have created a contract for erc721 token. The contract inherits open-zeppelin ERC721 smartcontract. When I deploy my contract on remix i can view the supply correctly however the max supply and ...
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what are the phases of PoA?

do the authorized nodes check the public key or the signature of each transaction in the beginning and how long it would take as the PoA is lightweight consensus
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Wallet providing seed money of an Ethereum address cannot be viewed on etherscan

On etherscan, what can be said about an Ethereum address that starts with a non-zero opening balance? we would expect there to always be a blockchain trail for all transactions. For example, at this ...
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How to run Chainlink Project using eth-brownie python

I had installed eth-brownie using command pip install eth-brownie after Brownie installed.I had bake existing Brownie project into a new directory. mkdir MyChainlinkProject cd MyChainlinkProject/ ...
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How to run a chainlink Node on Mac using chainlink source code

I had followed these setups Install Go 1.14, and add your GOPATH's bin directory to your PATH Example Path for macOS export PATH=$GOPATH/bin:$PATH & export GOPATH=/Users/$USER/go Install NodeJS ...
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Liquidity Of Token In Pancake

i tried to connect my token via pancake just want to ask if i remove LP of my token so ppl can still trade or not? And if someone bought my token will his money convert into LP? And if yes? Then if i ...
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Deploying Goose Finance Front end and Connecting it to Smart Contracts

I recently learned the fundamentals of Solidity and had some smart contracts deployed on testnets using truffle. Also, I've done a simple dapp by finishing dapp university tutorials on youtube. ...
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1answer
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Can a decentralized app know the true identity of its users?

I’ve been thinking about the architecture of decentralized applications. I know certain applications like Uniswap and Augur don’t know the identity of its users. Would these applications still be ...
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How i can start Trading My Token

I have created token also its live on BSCSCAN , how I can start trading on it. I tried via pancakes but there I have to deposit BNB for LP is there any other way?
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NFT (Rarible) double item

I’m new in NFT and Rarible as NFT sell point. I have enter one of my images to sell, but after 2 days of pending signing contract in my Coinbase Wallet, I received message “failed“. I have started ...
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How i can bun my tokens i tried this code but getting error

In last there is code of burning tokens please help me i am getting this error TypeError: Indexed expression has to be a type, mapping or array (is function (address) view returns (uint256)) --> ...
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Total supply of deployed token is wrong

I made a BEP-20 (ERC-20) Token. Can you guys suggest me what mistake i did. I am getting total supply 0.001 MKY. It should be 1000000. contract Token { /// @return total amount of tokens ...
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Server knows that a message is coming from owner of a token?

So I am trying to understand ethereum better, am an amateur. So excuse my naivete here. I am trying to think through this scenario to know if its possible, or how it could be implemented. If any of ...
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Is it possible to know which will get the next pending block?

Is it possible to predict which miner will mine the next pending block on ethereum mainnet?
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truffle flattener cannot find part of path

I am trying to flatten a solidity file but I keep getting cannot find part of path error as shown below out-file : Could not find a part of the path 'D:\Blockchain\bullrun\src\contracts\ERC721.sol'. ...
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Called a smart contract function(web3py), signed the txn. it executed successfully, but the block wasnt mined and the txn hash was empty. How do fix?

def addPatientDetailOld(request, name, location, phone, nin, email, dob, lga, state): private_key = request.session["key"] address = request.session["address"] transaction = ...
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Unknown metamask transaction

I logged into my metamask after a week, just to realize it was drained. I don't know how this could have happened, I just want to make sure I prevent this from happening in the future, should I ...
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Error: Invalid URL provided to HttpProvider

tronbox.cmd migrate --reset --network shasta Using network 'shasta'. (node:17820) UnhandledPromiseRejectionWarning: Error: Invalid URL provided to HttpProvider at new e (C:\Users\User\AppData\...
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How do i import my ethereum wallet just using private key?

Help me out how do i resolve the issue of ethereum smartcontract for getting my wallet when i enter my private key in the text area Use WalletUtils functionality The WalletUtils class can be used to ...

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