All Questions

I need to store the transaction details to my database. And here is my code: var rawTx = { nonce: nonce, gas: estimate_gas, to: contract_add, value: '0x0', ...

I ran two command lines of web3 and it returned an error > length ='0000000000000000000000000000000000000000000000000000000000000002' ...

I am trying to get two contracts to interact: pragma solidity ^0.5.10; contract C2 { address public addr; constructor(address per) public { addr = per; } function ...

I tried to deploy a contract to rinkeby then on ropsten, but getting an error: Network ropsten-fork Minting initial supply of 5000000000 ... Error: Error: Error: invalid address (arg="_to", coderType=...

Is there any code in the Raiden client that deploys a TokenNetworkRegistry contract?

I did this in rospten network, but when I use it in private parity network, I get transaction hash, but it isn't searchable at the explorer: const Web3 = require('web3'); const EthereumTx = require('...

Throughout the Raiden source code, the result of a state transition is called a iteration (for example https://github.com/raiden-network/raiden/pull/4791#pullrequestreview-285494821 ). Where does ...

Python version : 3.5.2. web3 version : 4.9.2. Ubuntu : 16.04. Also tried previous version of web3: 4.0.0

I'm trying to add some extensions to the ERC721 token standard. Usually, contracts should be desgined to be upgradable before deployment. The problem is that the contract is already deployed and the ...

I am working with a private blockchain, and am having a problem where simple functions and constructors simply fail to work. For instance: constructor(address admin) public{ owner = msg....

this is the token: MovieMarketCoin https://etherscan.io/token/0xa0005edc8897fe1f9e2705a1682431497a504657 Source code is here: https://github.com/Gh4Algebra/MovieMarketCoin I followed other answers ...

I want to keep a track of top 5 token holders inside the contract in terms of their token balances, is there any efficient way to do that in solidity?

I have an array like this in the array, uint256[] public numberArr= [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]; Each number in an array have their own weight, uint256[] public weightNumberArr = [1, 3, 9, 7, 15,...

I am writing a contract where I need to check that if in 5 minutes no new token get purchased then the sale should be ended. What I mean exactly is that, lets say user A has purchased 100 tokens and ...

I have an array of integers like this, uint256[] public numberArr = [0,0,1,1,1,1,1,1,2,2,2,2,2,3,3,3,3,4,5,5,5] What can be the best way to shuffle this array in solidity

Here are what I knew about them: eth.accounts.create: Generate an address and private key for transaction but did not stored in anywhere. personal.newAccount: Create an account under node, so that ...

Example of an address with the wrong checksum: 0xa54D3c09E34aC96807c1CC397404bF2B98DC4eFb Example of an address with the right checksum: 0xa54d3c09E34aC96807c1CC397404bF2B98DC4eFb -Difference ...

If the Set function receives two inputs 1.["0xca35b7d915458ef540ade6068dfe2f44e8fa733c",50,"ROC","park"] 2.["0x14723a09acff6d2a60dcdf7aa4aff308fddc160c",60,"AU","school"] How can I return all the ...

I am trying to install [eth-tester][1] Python Package so that I can use it to load test ethereum in my account by using its get_balance() function. First when i installed this package using; pip ...

Web3js frontend with Vue, .NET Core with Nethereum at the back. The key target for this functionality is to sign a message at the frontend, send the signature and the address to the backend to ...

In public blockchain a miner gets rewarded for mining a block. But in a private or permissioned blockchain, if there are no rewarding facilities available, how does the mining happen? Also, is it ...

Suppose I want to use blockchain to play chess for money. So, I can register, on the blockchain, a smart contract (a chess game) associated to some amount of ether. If someone wants to join, he or she ...

I need to interact with my web app that has blockchain functionality and it creates wallets on paper (pls dont ask why). It's using ropsten testnet. Is there an Android app that I can easily scan the ...

I get the following error when passing (new BigNumber('2')).exponentiatedBy(100) big number value as uint256 Error: invalid BigNumber string value (arg="value", value="1....

The expected outcome is very simple: Users will send their ERC20s to a smart contract. Depending on the amount, each user will get a file specifically created for them. I want to distribute that ...

I am trying to declare array of structure but its not accepting. I got this program from internet. pragma solidity ^0.5.1; contract NaiveBank { struct Account { ...

I need to allocate a winner among the token holders. I want to keep the concept that the more tokens someone buys the more chance there will be that he will be the winner. now lets say 960 tokens ...

Warm Greetings! I have a private ethereum blockchain setup on my server with multiple nodes , Also running mining software to mine blocks and earning private ethers (no value in market). Can i ...

I've been struggling to find a solution to the problem of upgradeability that maximizes trustlessness while also putting minimal burden on users. I really wanted to use signed messages to validate ...

Error: Error: ProviderError: VM Exception while processing transaction: revert at Object.run (C:\Users\WINDOWS\AppData\Roaming\npm\node_modules\truffle\build\webpack:\packages\truffle-migrate\...

I am learning/playing around with some concepts of the blockchain, smart contracts and Ethereum. I have created my own "toy" cryptocurency ("myCoin") by forking a coin using the CryptoNote algo. I ...

So I am writing my own smart contract on remix.ethereum.org, and it is for a token, and in the code, I have written a simple ICO: function() public payable { if (totalSupply >= 1000) { ...

Is there any secure and reliable way of broadcasting signed Ethereum transaction without using Web3 library like with some service and some sort of HTTP API?

I have a problem with using the deposit () function on a smart contract. How do you use metamask 0.20.7 ? const contractInstance = web3.eth.contract(contractAbi).at(contractAddress); contractInstance....

I have a contract being an ERC-20 token. I want to perform two idendical transfers (sender, receiver and amounts are the same). I am using the contract objects from Web3j: MyToken token = MyToken....

Trying to get the return function of a contract from another contract. Don't know what I am doing wrong. I can see the return value when I call contract A directly but when I try calling the function ...

I am using oraclize query. I have a function that user's invoke but I dont want users to pay the gas fee for oraclize query, I want that fee to be paid by my contract balance, and if my balance is not ...

Will nonce increase even when the transaction fail? For example, nonce=0 -> tx succeed nonce=1 -> tx succeed nonce=2 -> tx fail Then I want to send a new raw transaction, should I assign ...

During a tutorial on my first compile I received this error: :1:1: Parser error: Expected import directive or contract definition. pragma solidity ^0.5.12; ^ What's that about? How do I fix it? I'...

I have a function that is being called by multiple users (say 3). That value is set by owner earlier as a constant. Inside this function there's a check whether it's the last user (3) or not. If yes ...

Since web3 apparently doesn't require functions with uint parameters to have positive values for those parameters, I thought I'd try it in Solidity. I'm posting this to see if I'm overthinking it, if ...

How can I create Ethereum wallet addresses that can be revoked after certain time? Is it possible to do that? I am trying to create temporary wallets for employees in a company for their company ...

I'm testing to create a token in Truffle; it compiles fine, but it won't load the balance of the token in to Metamask. I've set the connection correct: it does load the ETH balances of the Ganache ...

I'm building a simple HTML/JavaScript front-end to interact with a Smart Contract using web3.js and MetaMask. I have a function to call one of the methods in order to send a contribution to the Smart ...

I am having problems passing data and connecting to nethereum. var temp = APIFramework.ConectClass.RegistroDeProveedor(RFC, RazonSocial, Domicilio); I send this string data to the methods I have for ...

I have tried nearly all desktop wallets, they are either based on Electron which does not run great on a Raspberry Pi with X11 Forwarding or don't seem to be open source, some have at least some ...

This is the file I'm trying to compile. I've been using truffle for a few years and I remember that we used to be able to compile files with different names than the contracts inside. I'm using ...

I used the command truffle unbox react to build a dapp. It is just the initial step of my dapp development. However, it sucks. It continually pops up gyp ERR! build error gyp ERR! stack Error: `C:\...

Description of issue I'm trying to debug a simple contract using remix on chrome v. 65 on Ubuntu. I must be doing something wrong, because I have the following issue: When I place a breakpoint in ...

I lunch a geth node in fast mode using geth --testnet --fast and I want to get incomming(pending) value for an account address using web3py, like web3.eth.subscribe('pendingTransactions') in web3js. ...