All Questions

I'm currently testing events that include numeric values: const level = new BN(1); truffleAssert.eventEmitted(tx, 'EventName', {level}); As you can see, the level variable is a BN, and holds the ...

Hardforks, such as Istanbul, have illustrated the best practice that smart contracts should not make any assumptions about gas. Gas costs have, can, and will change, for example: Is transfer() still ...

Ihave to compile some old contracts (having solidity pragma is <0.5. For this purpose, I have just copy and paste this contract from Etehrscan and save with its name in contracts folder. Install ...

I need to check the balance of several addresses for the presence of erc20 tokens, if the balance is not empty, send eth there and forward this balance to the resulting address. But in the end, I get ...

My question is that is it possible to modify the value of Gas limit per block in go-ethereum source code. If yes, which part of GasLimit value could be affected on the Gaslimit per block in source ...

I want to make a simple smart contract, but I don't know if smart contracts are capable of what I desire. Please tell me if they are: a user can send ETH (or any ERC20 token) to the smart contract ...

As the countdown on https://ethernodes.org/istanbul, should I need to stop my geth node before hard-fork? Or I could continue to syncing during hard-fork. Thanks alot.

function transfer() payable public returns(bool) { balances[msg.sender] = SafeMath.sub(balances[msg.sender], msg.value); if(msg.sender.call.gas(100000).value(msg.value)()) { ...

The ERC20 Token Standard dictates that functions transfer and transferFrom should return true for success and false for failure. However, various ERC20 tokens deployed on the network have not ...

In other words, is using transfer() safe? function transfer(address contractB) public { contractB.transfer(1000); //balances[msg.sender] -= 1000; } How about using call.gas? function ...

It says automatically sets environment for amd ...but also in v14.7 says both amd and Nvidia card supported except radeon7 cards...I guess what I'm asking is why can't I use my r7 or r6 ? I'm new to ...

Is there a CLI command where I can pass in an ethereum private key and send some coins to another address? I'm trying to build out a reoccurring payment system where a user can send 1 eth to another ...

Say I have a function that handles 4 cases via if statements. I could break that into 4 separate functions. The case for breaking it up is that each function call would use less gas. The case against ...

I'm looking at events on the exchange contract address: https://etherscan.io/address/0x61935cbdd02287b511119ddb11aeb42f1593b7ef#events with a topic_0 equal to ...

I have almost 800 .solc files of version ^0.5.12 (i am using also 0.5.13 compiler version), when i all give them to my input, to compile with following code; var walk = function (dir) { var ...

To automate the signing capabilities I'm happy how clef is working. I've a couple of concerns though. answering the commandline prompts on clef init, clef clef attest, and clef. I'm wondering how i ...

I am new in solidity and i want to know about arbitration and dispute functionality in smart contracts any help will be appreciated

Most tokens simply utilize the ERC20 functions transferfrom/transferto which just use some balances to add from one user to another - but what are the ones who allow you to: buy token cashout to ...

I modified go-ethereum source code and built it. I am wondering if I want to test and run geth with the modified source code in mainnet or testnet, and how it works in the mainnet or testnet. How to ...

I have created a mySQL database through phpMyAdmin, storing health data. I would like to use Solidity to develop a smart contract which will implement access control to the data in the database. My ...

I have the following solidity contracts defined. I want to test nested calls using the lowlevel api where C->D->E. However, running this code passes on ganache-cli but fails on geth --dev node. Im ...

i was checking into EVM gas table (https://docs.google.com/spreadsheets/d/1n6mRqkBz3iWcOlRem_mO09GtSKEKrAsfO7Frgx18pNU/edit#gid=0) (even though it is old sheet) Have few question: On what basis for ...

I need to send eth to accounts that have erc20 tokens: foreth.forEach(function(item,i){ const balance = contractInstance.methods.balanceOf(item).call(function(err, result) { console.log(...

I'm not familiar with webpack, but after reading this error all I know that I import one module that is undefined by webpack. However, I don't know why export default new web3.eth.Contract(abi, ...

Web3Shim { currentProvider: [Getter/Setter], _requestManager: RequestManager { provider: HttpProvider { host: 'http://127.0.0.1:7545', httpAgent: [Agent], withCredentials: ...

I create my transactions with ethers.js and push them into an array like this: const promises = []; promises.push(createTokenApprovalTx()); promises.push(createFooTx()); It's important that the ...

[SOLVED]: See below. I am taking a blockchain and security class and we are working with vyper. We have been tasked with rewriting a fundraising smart contract. However, the compilers do not seem to ...

I need to connect to Mist without access to internet. How I can do it without download any other software?(except geth, of course) With a default connection, I get errors: [ERROR] Sockets / node-ipc -...

Is it possible to take input of a string from client side and using smart contract write that string data to a new block inside the Ethereum blockchain mainet or any testnet? Basically take in ...

When making a contract transaction using go-ethereum (golang) how can I decode the transaction inputs. Specifically Given a tx.Data []byte , the contract's contractABI abi.ABI and the method that ...

I have an event defined like this: event Created( address indexed target, string indexed name ); I do emit Created(..., _name); // called function with _name = "comment" which gives ...

I'm getting this error: Error: invalid type (arg="type", value="function") when trying to call this method on the contract IntOption: function create( address target, string memory name, ...

I have a typed signature generated by EIP712 V3. It is 132 characters long. I'm trying to recover it using recoverTypedSignature from eth-sig-util. This fails saying: index.js:1 Error: Invalid ...

Can I please get some help with the following? Is it acceptable practice to allow my functions to rely on require statements "passing" to return the correct value? In the example below if the ...

There is a code, the essence is this: I need to check the account balance for erc20 tokens, and if the balance is not zero, I need to send eth from another account to this one, after eth reaches the ...

I need to send erc20 tokens from one address to another, provided that the token balance is not empty. I check the balance as follows: const balance = contractInstance.methods.balanceOf (...

This is the classic reentry attack: function withdrawBalance() public { uint amountToWithdraw = userBalances[msg.sender]; (bool success, ) = msg.sender.call.value(amountToWithdraw)(""); ...

I'm trying to reduce the storage size of my contracts by reducing the bytes required to store my int data types (among other things). Can I get the best practice for adding int256 and other smaller ...

I am trying to send ether from one address to another. After executing the code I am receiving an error: Cannot read property 'then' of undefined. How can I fix this? Thanks in advance. const Web3 = ...

I am wondering if there is a best practice when using web3py to generate an account, i.e private key, and save to to a database. Which format should I use to save it to a database? does web3py have ...

I need to verify the signer of a signature in my node server. const fortmaticApiKey = 'pk_live_...'; const checkPersonalSignature = async (data, signature, signer) => { try { const { get } =...

web3.js has the ability to call a transaction and get return data without sending a transaction: web3.eth.call(callObject [, defaultBlock] [, callback]) ethersjs apparently does not have this ...

Consider a getter function with a restriction on who can read it, like function getData() public view returns (uint x) { require(msg.sender = '0x123..123'); x = data; } This ...

I know how to do it for a constant function, for example: pragma solidity 0.4.25; contract Callee0 {function func() external pure returns (bool) {return false;}} contract Callee1 {function func() ...

I am trying to transfer ERC20 tokens on private ethereum network(POA) Transaction flow: raw tx object creation on backend. { "gasLimit": 37000, "gasPrice": 4000000000, "...

I try to send eth from one address to another, but I get an error: Returned error: The method eth_sendTransaction does not exist / is not available const Web3 = require('web3') const web3 = new Web3(...

I am developing a Web3 app for a private Ethereum network. Throughout the development I used ganache-cli and now I wanted to test in the private live network. I can successfully interact with the ...

I'm trying to get all events from contract, but get error: "ValueError: {'code': -32601, 'message': 'The method eth_newFilter does not exist/is not available'}" I'm using Web3py and Infura. My code: ...

Example in this scenario I guess selfdestruct will never get called (also: contract A isn't so important by the way just focus on B onward): in Contract A: address contractb = 0x....; function ...

My question is if I'm not implementing ERC-20 methods in my contract, but I'm using already deployed ERC-20 contract methods in my contract, so can we say this will be ERC-20 compliant contract? ...