All Questions

0
votes
0answers
2 views

Private chain access mode

I set up a private chain with 4 nodes.Two nodes are sealer, the others are normal ones. To send a transaction, need to attach one node and then send it. I think in this way, only one node is used to ...
0
votes
1answer
5 views

How much gas does looking up block.timestamp consume?

Trying to get some insight as to whether or not it's more optimal to call block.timestamp repeatedly for comparisons or to set a (memory) variable to hold the value and use it instead. I've looked at ...
0
votes
0answers
5 views

Parity Mnemonic or Keyfile not compatible with MEW?

I'm on a new computer and I have 2 ETH addresses I created on parity in december 2017 and february 2018. Now I thought I followed the plan on what to do to secure the addresses but when I enter the 12 ...
0
votes
0answers
8 views

Parity synced at not existing block 4839212

I have problem with parity, cant get synchronization in archive mode to end, anything, changing arguments, max-, min-, snapshot-peers, parity verisions do not help. I have blockchain in archive mode ...
0
votes
0answers
5 views

Java class generated with web3j has a “deploy” method wherein initialWeiValue, initialSupply have to be both specified. Isn't it the same amount?

Method in the java class generated by web3j is like this: public static RemoteCall<Crowdfunding> deploy(Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit, ...
0
votes
1answer
14 views

What happen when I format my blockchain setup PC?

Suppose I have ethereum blockchain network setup in my PC and when I format my PC how I will recover my data? Normal in client server architecture my data doesn't depend on my PC whether I format or ...
0
votes
1answer
7 views

VM error transaction has been revert to initial state

pragma solidity ^0.5.8; contract PharmaChain { address public superAdmin; //address of the super admin uint quotlist; enum Status { NotExist, Pending, Aproved, Rejected, ...
1
vote
0answers
6 views

truffle unbox react - front end is unable to read / set state of the contract

I am experiencing problems with the Truffle React boilerplate code that the front end is unable to read / set state of the contract. Here are the details: I unboxed the React boilerplate using ...
1
vote
0answers
2 views

Access to XMLHttpRequest at 'https://ropsten.infura.io/' from origin 'null' has been blocked by CORS policy

I want to interact with a simple contract on the ropsten network this is my Js code : Web3 = require('web3'); if (typeof web3 != 'undefined') { web3 = new Web3(web3.currentProvider); console....
0
votes
1answer
14 views

How do I deposit Ether to Smart Contract using Web3.js

So I am creating a web application that interacts with a smart contract that I deployed on the Ropsten TestNet. I am able to withdraw ether from the contract to my Metamask account using a withdraw ...
0
votes
0answers
8 views

How use vscode to debug geth with breakpoints interactively?

I set up vscode enviroment and launch a node with launch.json: { "name": "Launch geth main", "type": "go", "request": "launch", "mode": "debug", ...
0
votes
1answer
31 views

Unable to deploy the smart contract using solc compiler in mac

I am trying to deploy the Lottery contract using solc compiler of verison 0.4.17 but it's showing me nothing. But the same contract is working good in the remix ide. I providing you the the Solidiy ...
0
votes
0answers
16 views

The method eth_sendTransaction does not exist/is not available on infura

Im trying to send transaction to simple greeter contract with web3.js on infura node.while doing soo, Im getting this error. throw errors.InvalidResponse(result); ^ Error: The method ...
0
votes
0answers
12 views

Accidentally sent REN (ETH token) to my ETH contract address using my Ledger Nano S. Can someone help please?

I sent REN (ETH token) to my ETH contract address by accident while using my ledger nano s. Can someone help me understand what's happened to the tokens and if I can retrieve my REN token from my ETH ...
0
votes
1answer
15 views

Privacy concern

I have a smart contract where user submit data based on a task set by the owner, post doing so the owner in another contract offers this data to the highest bidder. Is it possible to ensure the ...
0
votes
0answers
11 views

ERC721 how to use tokenOfOwnerByIndex() to list tokens owned by a user

I'm trying to list ERC721 tokens owned by a user. I found there is tokenOfOwnerByIndex(address _owner, uint256 _index) that can make the looping shorter. When I checked ERC721Token.sol from ...
-1
votes
0answers
7 views

Error! Invalid constructor arguments provided. Please verify that they are in ABI-encoded format

I having trouble Verify & Publish Contract Source Code Here is the code /** * Source Code first verified at https://etherscan.io on Friday, May 10, 2019 (UTC) */ pragma solidity ^0.5.0; /** ...
-2
votes
0answers
7 views

truflle consile error BN { negative: 0, words: [ 0, <1 empty item> ], length: 1, red: null [on hold]

i was getting error in truffle console BN { negative: 0, words: [ 0, <1 empty item> ], length: 1, red: null
1
vote
0answers
6 views

What is the value range of the parameter optimize-runs when running the solidity compiler?

I would like to know what the allowed value range of the parameter optimize-runs is when running the Solidity compiler. I didn't find the answer in the official document of Solidity.
0
votes
0answers
8 views

metamask-BSC=ETH

Dear support please explain how i can BSC To ETH I'll convert to 29,000 BSC I sent to this address ETH 0xdc05a177e5691ea5294fdbee712f5ab18f474b34 Please see the link below from my problem https:...
0
votes
0answers
11 views

I accidentally sent ETH token REN to the contract address. Can I get it back?

I sent my REN to the contact address by mistake. (0x408e41876cccdc0f92210600ef50372656052a38) Please help. I was meant to send it to my REN funds address While using my Ledger I mixed up the contract ...
0
votes
0answers
16 views

How does this assembly function work?

From the Docs, how does this operation create a new "memory end"? mstore(0x40, add(o_code, and(add(add(size, 0x20), 0x1f), not(0x1f))) Context: library GetCode { function at(address _addr) public ...
0
votes
0answers
6 views

Transfer function not working properly with calculations

function payWorker1(address schoolId) public payable returns(bool){ require(Schools[schoolId].moneySent == false); require(Schools[schoolId].verified == true); Schools[schoolId]...
2
votes
1answer
17 views

Metamask injects one account in web3, but calls contracts using another account

Building a React app, MetaMask injects web3, I get accounts[0] from getAccounts(), then pass it to my contract functions together with other parameters. I want my modifiers to lock incoming function ...
0
votes
1answer
23 views

ecrecover not giving back the adress of the sender

I am trying to understand how eliptic curve work and when i try to get the sender of this transaction: https://etherscan.io/tx/0x14a298c1eea89f42285948b7d51eeac2876ca7406c9784b9b90dd3591d156d64 ( ...
0
votes
1answer
19 views

signing transactions with web3.js

Im trying to create a node.js based dapp that interacts with ropsten ethereum network via infura node.here we need sign transaction with web3.js. but the code showing error from the contract side. ...
1
vote
1answer
19 views

How to increase the number of test accounts?

I have encountered a problem where I need a large number of test accounts. How can I increase the number of test accounts from 10. Remix and ganache only give 10 accounts. I require more than that.
1
vote
0answers
29 views

openzeppelin,VM Exception while processing transaction: revert

using openzeppelin-solidity to create crowdsale. Then I use this statement to Buy Token: MyCrowdsaleInstance.sendTransaction({ from: purchaser[1], value: web3.utils.toWei("0.5", "ether"), ...
1
vote
1answer
21 views

Airdrop generated token to multi address by contract failed

Below is my operation steps: I create a token 0x260c4b1cd063599949b530454d22081b94c170ef whose owner is 0xAbA5862c54254750b2EFe8BEB72f528DAF73547F You can check this token's code by https://...
1
vote
1answer
18 views

Return fees - is it save?

I would like to return partially fees to users of my dApp. Once they have reached X amount in fees, I want to make a function that will pay them ethereum automatically. Now my question: Is that secure?...
0
votes
0answers
10 views

how do most of contracts sell service(or items) to user usually?

how most contract sell service to user usually? I think there could be 2 ways 1. user just tap buy button to call buy function in dapp contract then contract does itself 2. when user tap buy button, ...
1
vote
1answer
5 views

When I tap buy button in market how does wallet check my allowance instantly?

On CrytpoKitties, when I tap the buy button in a market, MetaMask comes up and shows if I can buy or not based on allowance instantly. How is this possible? Is it making query? Is it included in kitty'...
0
votes
0answers
10 views

getting an error while deploying smart contract of ethereum

I am getting an error while trying to deploy smart contract of voting dapp on ethereum I have searched for the solution for the same and i got a question with same problem but there no solution. ...
1
vote
1answer
9 views

can contract check mining of certain transaction in real time?

I want to make logic following A user send token to B(transaction #1) contract check in realtime whether transaction #1 is mined or not. If it is mined, contract goes to next step. How can I make ...
1
vote
1answer
4 views

Do dapps(contract) check allowance of buyer when he calls buy function?

When a buyer calls a buy function on dapp contract, some dapps check the buyer's allowance before transfer tokens(erc20). Is it usual?
0
votes
0answers
6 views

Parity build error

mac os 10.14.4 CMake-3.14.4 was installed by running the bootstrap script in CMake-3.14.4 directory. then ran $ git clone https://github.com/paritytech/parity-ethereum $ cd parity-ethereum $ ...
0
votes
0answers
7 views

clique 2 nodes stuck mining after outage for one of them

i have setup a network of 3 nodes, with 2 of them being sealers (clique) and a third one acting as a proxy. I know there should be an odd number of nodes to avoid split brain scenarios, but the goal ...
3
votes
1answer
24 views

Ganache + Truffle: how to deploy a contract without considering the gas

I am working with Ganache and Truffle. I am trying to deploy kind of a huge smart contract, but most of the functions in this smart contract are pre-prod functions, so I do not really worry about real-...
0
votes
0answers
8 views

iOS Wallets that support testnet

Is there any good iOS app that supports custom erc20 tokens over testnets like Rospten? I’m testing new custom tokens and need to test it over a test net before deploying to the main-net. Thank you
0
votes
1answer
20 views

Automating user data storage on a blockchain

I have a smart contract that contains a function to store data onto the blockchain. The function stores two integer variables to the blockchain. Now, I can manually store the values from the remix-ide ...
0
votes
0answers
23 views

Is latest block returned by eth.getBlockNumber fully processed

According to web3 docs, web3.eth.getBlockNumber returns the number of the most recent block. My question is simple. Is it safe to assume block's transactions and events are already in the node or ...
1
vote
0answers
13 views

MetaMask returns different error - not longer working

I am calling the MetaMask promt successfully with this: ethereum.enable().then(response => { console.log("ABC"); }).catch(error => { console.log("XYZ") }); However, when I disagree ...
0
votes
1answer
40 views

Sending transaction with web3.js

I'm trying to use web3.js with infura.io to interact with my smartcontract. here is my simple greeter contract code pragma solidity ^0.5.7; contract greeter{ string greeting; function greet(...
0
votes
1answer
12 views

pass storage through interface to library

Here is what am i doing: There is a library, accept storage argument as parameter, then do some math and return the result. And there is a contract to call the function in the library, and an extra ...
0
votes
0answers
14 views

transfering ERC20 token from one account to another and some percentage of it will reflect into some more acoount [on hold]

I am sending token(100) from my account to another then some percentage of it will reflect to other account also ex- 10-10 erc20 token will reflect to other two account also.
0
votes
0answers
7 views

Mist showed my wallet one day but after I restarted it, it disappeared

trying to see if there's any hope in restoring my wallet. I opened my Mist application for the first time since 2017 and was able to see my wallet. When I restarted it the next day, it was gone. I ...
0
votes
3answers
34 views

Remix: This contract does not implement all functions and thus cannot be created

I'm new here and code with openzeppelin framework 2.2.0. There is no error occurred when compiling with solidity 0.5.8. But when I'm going to deploy the contract, I have no bytecode and cannot ...
0
votes
1answer
16 views

Multiply small rational number to obtain integer piece

I'm trying to make some advanced calculations in Solidity. I was able to successfully implement the algorithm on my contract, but its results are way below zero, and whenever I try to get it with ...
0
votes
1answer
23 views

Smart contract architecture [on hold]

I want to write the smart contract architecture for a new smart contract on Ethereum ERC20, how can I do that, and what does it mean smart contract architecture.
1
vote
0answers
48 views

How to remove whitespace from string?

I have a function where one of arguments is a string. How would I check the string for leading/trailing whitespace and remove those characters? If i get something like this: " " => "" or " ...

15 30 50 per page