All Questions

1
vote
1answer
20 views

My parity node ran out of space- I have over 100GB free and am using warp-barrier. Is this normal?

Error message below. This doesn't seem right, I'm only downloading a little over 20k blocks (which is the whole point of warp barrier), how can this really need more than 100GB? Just to clarify, it ...
0
votes
0answers
20 views

web3j.ethCall returns null when retrieven contract variable

Environment: Geth node Geth/v1.9.0-unstable/windows-amd64/go1.12 Commands used to start the node to mine: geth --datadir "." --networkid 101 -verbosity 6 --port 30301 --rpcport 8101 --nodiscover -...
0
votes
1answer
54 views

Genesis allocation and (address, balance) tuples

On go-ethereum souce code at core\genesis_alloc.go(19): ... package core // Constants containing the genesis allocation of built-in genesis blocks. // Their content is an RLP-encoded list of (...
-1
votes
0answers
61 views

Error while truffle test

C:\Users\Dreams\Newcontract>truffle test Using network 'development'. Compiling your contracts... =========================== > Everything is up to date, there is nothing to compile. C:\Users\...
0
votes
1answer
17 views

how to connect my html form that is username and password to blockchin and taking the username as metamask key?

I am developing a decentralized cloud web application, when the user will login into the application he/she will generate password from blockchain, I am not getting how to connect my html form that is ...
0
votes
0answers
13 views

ERC-20 TransferFrom function exceeds GasLimit calling from other conract

I have the following error. Imagine that I have contract A, B(ERC20 implementation contract), C, D and E. They are inherit in that order. Testing the functionallity works fine in remix. But when I try ...
0
votes
1answer
11 views

Block sealing failed err=“unauthorized signer”

i am trying to run geth environment on windows after i have successfully set it up on linux. When trying to deploy contract on geth like i did in linux it produces following error. loadScript('...
0
votes
1answer
17 views

Is there a good erc20 source using web3js?

I'm looking for some source codes using web3js for interaction with erc20 tokens and contracts. Does anyone know good source codes using web3js? Thanks in advance!
0
votes
0answers
5 views

How to make contract on MEW to forward all eth from address to address automatically every second? [closed]

help me please. How on MEW with new interface make contact that will forward all future transactions on other address? For asnwer that helps i will send 0.30 eth Thank you!
0
votes
0answers
12 views

Duplicate values added to array and map for a particular function

I'm trying out my hands on a dApp development. For some reason, I'm unable to understand what went wrong in the following function. contract transactions{ enum ExpenseTypes {DEFAULT, EQUAL, ...
1
vote
1answer
35 views

ERC 20 or ERC 721 for my dapp?

I am currently making a game where you collect gear pieces and upgrade them. There will not be a 1-1 upgrade, but rather 3-1, meaning 3 items may or may not upgrade to 1. I am aware of the difference ...
1
vote
2answers
121 views

what is the meaning of 0x0? say when variable gets assigned to it, example: keccak256(number) = 0x0;

Is 0x0 just zero? thanks keccak256(number) = 0x0; Or when not used as address I mean just to denote variable?
0
votes
1answer
27 views

How can Contracts sign transactions, when they dont have a private key?

When transactions are made the sender is identified by his signature. But Contracts dont have a private key to sign any transaction or message. So I have some questions: Can a Contract initiate a ...
1
vote
1answer
29 views

Ideal way to store hash on the ethereum blockchain

I would like to store a certificate on the blockchain. I only need to store its hash and if its been verified by both parties or not. Should I create a struct that is made up of bytes32 for the hash, ...
0
votes
0answers
17 views

Error while running npm run

sh: 1: lite-server: not found npm ERR! file sh npm ERR! code ELIFECYCLE npm ERR! errno ENOENT npm ERR! syscall spawn npm ERR! eth-todo-list@1.0.0 dev: `lite-server` npm ERR! spawn ENOENT npm ERR! npm ...
1
vote
1answer
30 views

I can't able to understand the following function in the solidity

function multiowned(address[] _owners, uint _required) { m_numOwners = _owners.length + 1; m_owners[1] = uint(msg.sender); m_ownerIndex[uint(msg.sender)] = 1; for (uint i = 0; i < ...
0
votes
0answers
13 views

Sending an extra percentage of a token someone is trading to a cold wallet storage address

I have an erc20 token I want to start trading. In the smart contract, can you make it send 1% of the transaction amount in the token being sent to a "company wallet" storage along with the wallet it ...
0
votes
1answer
39 views

How can I decode transaction input to know what method was called and what arguments were passed in (and arguments types)?

following to the approach explained here to use etherscan api from Python to get transactions info such as input How to retrieve transactions' info such as gaslimit and gasprice from Etherscan? ...
0
votes
0answers
22 views

Is it possible to implement upgradable contract with new functions?

I have follows this answer related to Upgradeable smart contracts and Zeppelin's solution. I have tested those examples, where I was able to update the interface of the functions that are already ...
3
votes
2answers
54 views

Truffle Test Issue With `address payable` and Compiler Version

I am trying to run truffle test on an old contract which was written using pragma solidity 0.4.24;. While I am able to deploy the contracts using truffle migrate, I get the following error when ...
1
vote
0answers
20 views

Why is one of my transactions using more gas when both carry out the same function of sending ether?

Below are two functions that I have in a simple lease smart contract. I am running a TestRPC node with Remix on version 0.5.1. When I call the terminate function, it executes and terminates the ...
0
votes
0answers
19 views

Best way to support restoring of all the keys of a mapping

I have a contract, in which I maintain the keys of a mapping in two different ways: Storing each key in an array Emitting an event for each key I do this in order to be able to restore the keys (and ...
0
votes
1answer
15 views

Cannot retrieve data from smartcontract during tests

I am writing truffle tests for my smart contract solidity version 0.4.24. The tests are emitting events to write data to memory through smart contract. But I am unable to retrieve data from functions. ...
1
vote
1answer
28 views

Smart contract now vs javascript now

I have a trouble with comparing timestamp parameter(in test) and now in smart contract. Here is my smart contract: function create(uint created_at) public { require(now > created_at, "The ...
0
votes
0answers
14 views

BlockChain Suitable for Payment based Mobile App [on hold]

I have a requirement where mobile app with below main specifications needs to be developed: Process user's check deposits and direct deposits and load amount to user's wallet. Peer to Peer Payment (...
0
votes
0answers
8 views

what's the functionality of the core/vm/runtime package, especially runtime.go

When i try to find the workflow of Creating a contract in Ethereum, I found besides two general entries for calling contract creation function, executing tx and verifying tx respectively, and there ...
0
votes
1answer
48 views

Mapping problem

**I am Using Solidity compiler 0.4.11 When I compile my code i get the error that is " Error: Type "mapping(string => string)" not supported for state variable.\n\tmapping (string => string) dataLink *...
0
votes
1answer
27 views

Two smart contracts interacting, should they know each other?

This may sound like a very naïve question. It's the first time I'm making interact two smart contracts (in general, I'm not very proficient with blockchain development). I have these two smart ...
1
vote
2answers
32 views

Smart contract that receives only one token

Is it possible to forbid to a smart-contract to receive all erc20 tokens and ether except my own token that was created in another contract? I mean I want my contract to receive only tokens from ...
0
votes
1answer
23 views

How to get total values in mapping and details of each transaction

I am trying to write a simple contract contract students{ uint public totalTokens; constructor() public { totalTokens = 800; } struct Students{ uint amount; string givenFor; } mapping (...
2
votes
2answers
55 views

Cannot able to call the contract inside the truffle console

I am new to the truffle framework. I have initialised my contract Dapp with the constructor function as given below pragma solidity ^0.5.0; contract Dapp { uint public totalSupply; ...
1
vote
0answers
13 views

Can I extend the interface of a contract without redeploying it?

The case I'm dealing with is a contract which should serve as a Data Abstraction Layer. So ideally, it should provide only getter functions and setter functions. For example, my interface is: ...
0
votes
0answers
25 views

Type Conversion

I am getting an error on line "_tmp[i] = bytes1((_base % 10) + 48);" and it says explicit type conversion not allowed from "uint256" to "bytes1". The code snippet which i have enclosed converts an ...
0
votes
1answer
12 views

error handling in sending custom token to multiple addresses in one transaction

i am trying to write a contract in which there is a function to divide the amount into equal parts and then deposit it into multiple accounts in one transaction. The problem is that, i want function ...
0
votes
0answers
13 views

Transferring crypto tokens [closed]

I have created a smart contract in remix IDE and deployed successfully, I need to transfer my token (From distributor wallet to users wallet) through my website. I have tried various d-apps it is ...
0
votes
1answer
35 views

web3.eth.getAccounts(console.log) Error

Can you please help me with this error ! How to fix this ?? web3.eth.getAccounts(console.log) TypeError: this.provider.sendAsync is not a function at RequestManager.sendAsync (/home/...
0
votes
0answers
63 views

About gas limit and gas

I'm developing Dapp, In that app one function consuming a gas but I am providing sufficient ether at the time of initiating transaction by web3 for the Dapp Users,Then also it is showing out of gas ...
0
votes
1answer
43 views

Truffle tries deploy from unknown account

I am trying to deploy a contract to Ropsten using Infura with the config file truffle.js below. The deploy fails because the account listed in the error message has insufficient funds – however I do ...
0
votes
0answers
24 views

Deployment Failed. hit a require or revert statement somewhere in its constructor

Im having now this issue deploying (in rinkeby): Error: *** Deployment Failed *** "FairInitialTokenOffering" hit a require or revert statement somewhere in its constructor. Try: * Verifying that ...
2
votes
1answer
28 views

Signing meesage | hex string has length 64, want 40 for common.Address

I am using 'web3.eth.sign` to sign a message, using following code snippet: web3.eth.sign(msgHash, address, async (err, signedMsg) => { if(err) { console.log(err) resolve(false) } else ...
0
votes
1answer
20 views

how to get contract creation code (bytecode) from etherscan api?

I tried etherscan api to get the contract creation code (bytecode for depolying contracts). I tried both getContractABI and getSourceCode, but the return values are not what i am expecting. I need ...
0
votes
0answers
15 views

web3.eth.personal.unlockAccount requires 3 arguments

I am using following code to unlock an account. web3.eth.personal.unlockAccount(address, password); But I get an error message: Error: Invalid Arguments length: expected: 3, given: 2
1
vote
0answers
10 views

MEW iOS App crash on contract deploy

I'm trying to deploy a contract via the UI on http://myetherwallet.com/. The contract was created with the Remix online IDE and when pasting the bytecode and ABI/Json interface contract pieces, the ...
0
votes
1answer
25 views

Solidity Contract Deployment fails - but account has plenty of ETH

I was just trying to deploy a new contract on the Ethereum MAIN-Net (not Ropsten, Rinkeby or the other test-nets) - and I’m getting this strange error: Message: sender doesn't have enough funds to ...
1
vote
0answers
24 views

Geth/Ropsten light node can't find suitable peers even after adding peers

I am trying to deploy a test contract on Ropsten test net. I have started a light node using the command: geth --testnet --datadir=./.ropsten --syncmode=light --rpc --rpcapi="personal,eth,network,...
1
vote
0answers
21 views

Simplest way to connect Mist to a node

What do you guys think the simplest way to connect Mist to geth running on another machine? I'm running geth 1.8.23 on another machine using ./geth --rpc --rpccorsdomain "*" --rpcapi "db,eth,net,...
0
votes
1answer
18 views

Replacing a requirement for TRC10 token with TRC20 on a TRX contract

I have a contract that allows users to buy a token and pay with a TRC10 token deployed on Tron. Is it possible to replace the token ID with a TRC20 address instead? And if so, how do I implement it? ...
0
votes
0answers
10 views

Possible to obtain a list of token transactions within a specified date range?

For example: Let's say I want to see the transactions for a range between January 1, 2019 - Janurary 15, 2019. I'm looking at the etherscan API but it doesn't appear to do this. It allows you to ...
0
votes
0answers
11 views

TypeError and ReferenceError in truffle test

Im newbie and doing an exercise Im having this errors at truffle testing: Compiling your contracts... =========================== > Everything is up to date, there is nothing to compile. ...
0
votes
0answers
6 views

transferAnyERC20Token on private network is not work,but on dev network is wrok

i start a geth window with this: then deploy a ERC20 contract : pragma solidity ^0.5.0; // ---------------------------------------------------------------------------- // Safe maths // -------------...

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