All Questions

I'm having trouble understanding the flow: Contract <==observes/injects== Oracle <==requestdata==> API I read several articles like this and I'm aware of the theory of the flow. But what ...

The following variables here, assuming solidity 4.24 or later. mapping(something => something) private yourmapping; bool private yourbool; address private youraddress; uint256 private ...

I'm trying to benchmark geth full sync. Here are my current machine specs: Google Cloud 16 vCPU 14 Gb RAM 700 Gb NVMe SSD RAID 0 772k read/258k write IOPS 6+ Gbps network Launching with following ...

Let's say I want to redirect somewebsite.eth.link to www.otherdomainiown.com. http://spacex.eth.link/ does this and the redirect works on chrome. However, I don't see an A record and I do see IPFS ...

I have read about zk-SNARKs on different articles which is written in 2016. So I am wondering if the zk-SNARKs is implemented in Ethereum currently?

I called the mint function on a default coin to send some of my new coin to my METAMASK account but it looks like nothing was received. I can't tell what specifically could have gone wrong, so here's ...

I'm using node library with web3.js, big number, and ethereumjs-tx, and I can get the "buy" orders that use either solidity function ethToTokenSwapOutput or tokenToEthSwapOutput to work great. But I ...

Solidity 0.6.2 allows the creation of contracts with the create2 opcode via the new keyword and passing a salt in addition to any args. This is adequate for creating standard contracts, but what if I ...

Ethereum relies on Oracles to provide information about the outside world used by SmartContracts. Also, when a node syncs (in slow mode) it has to go over all transactions (including SmartContract ...

I am currently trying to test a smart contract using the truffle suit ( with 'truffle test'). My contract is of a simple ERC20 token which includes the standard Transfer event: event Transfer(address ...

Here is my code example: pragma solidity ^0.5.16; pragma experimental ABIEncoderV2; contract Operations { Operation[] public operations; struct Operation { uint startOperation; ...

I have a bunch of contracts which deploy just fine. Deployment of one of the contracts, XBRNetwork takes exactly 5418911 gas - no problems with that. However, once I add another trivial (public) ...

Can I deploy a contract in Solidity (not in-line assembly) using create2?

in this code what is part 1 part 2 part 3 part 4 contract MyContract { // part 1 uint count; uint[] totalPoints; function localVars(){ // part 2 uint[] localArr; // ...

Assume Client A wants to sell a package to client B.

Does the Besu client support Plasma? I guess this question could also be asked about other clients such as Geth and Parity as well.

What are the differences between web3.eth.personal.getAccounts() and web3.eth.getAccounts()? environment truffle: v5.1.7 using truffle console.

I am trying to refer to this Solidity Docs https://solidity.readthedocs.io/en/v0.6.2/control-structures.html and trying to execute the following code pragma solidity >=0.4.0 <0.7.0; contract ...

in ethereum yellow paper it says: "There exists a seed which can be computed for each block by scanning through the block headers up until that point. From the seed, one can compute a pseudorandom ...

when I use solc instruction compile following code that get bin & abi: pragma solidity ^0.6.0; contract TestContract{ function multilpy(uint a,uint b) public pure return (uint){ return a*b; ...

Is it a good practice to create a smart contract to serve as a DB table? For example, lets say that I have users that need to create Operations. My operations objects need to contain id, description,...

function transferFunds(uint _value) private { uint _fee = (3*_value)/(2*100); //Perform Ether transfer method merchant.transfer(_value - _fee); admin.transfer(_fee); ...

contract TypeConversion{ uint96 data = 5; bytes32 b = bytes32(data); } It gives error: Explicit type conversion not allowed from "uint96" to "bytes32". What will be the better way to ...

I have developed a voting system usinh dapp that runs on local host. It uses accounts from ganache and metamask for transactions of votes. Now if i want to buy a domain and make the thing work, is it ...

I have created a Dapp that is written in Solidity and compiled with Truffle on both Rinkeby and Ropsten. I have also created a frontend for batch file uploads and a backend for the actual deploying ...

I am signing a transaction by using a private key in AWS Cloud HSM. But not able to recover the correct public key from the signature. Every time I try to run ECRecover method, it generates different ...

So, I started 2 nodes on my private net using geth, with custom genesis file, different port numbers, all how it was supposed to be. In one instance I added the admin.nodeInfo.enode of the other ...

I am currently testing the Oasis Saving Dapp by MakerDao (https://oasis.app/save). After converting some DAI to DSR, users can earn savings and whenever they want, withdraw their funds (convert back ...

Need to know every single js console command inside geth like eth.syncing, eth.accounts etc... Can anyone brief into this?

Just cannot get what seems like a simple input from html page to interact with a very simple contract to input data. Started off trying to make this tutorial work: Interacting with a Smart Contract ...

From a JS web3 file, I am calling a simple function that returns the wallet balance. function readCustomerBalance() public view returns (uint) { return msg.sender.balance; } Works fine in Remix. ...

I want to create something like a Crypto exchange, in which I need to generate different unique deposit addresses for each user, so they can send funds to their accounts while I can keep track of how ...

I thik it is kind of clear to me that of 50%+1 attack, but now i am thinking about something that occurred when i was testing a DAPP in a two node network. Each node had a blockchain (the same ...

I have a smart contract deployed having the following function. function getTime() public view returns (uint){ return now; } However, when I try to call the function like this. ("einstance"...

Im trying to run geth attach on my console , i have already started a node , this is the script that i used : #!/bin/bash geth --identity "miner1" --networkid 42 --datadir "~/Desktop/Tutorials/...

Since the ethereum Python library has been deprecated in May 2019, the ContractTranslator.encode_abi function is probably not the best way to turn Python argument lists into calldata strings. In ...

I have been looking into sharding and I wanted to figure out how much extra fee or gas does a person needs to spend on a cross shard transaction compared to a transaction within a shard. What could ...

I am trying to replicate the famous DAO attack for a cryptocurrencies course. I have the following contract already deployed on the blockchain. pragma solidity ^0.5.4; contract EDao { address ...

I deployed an ERC20 at this address: 0x60c56fb23dc18c719491759b6c40cd46e502fcbd One of the addresses I own got a huge balance (more then the token supply) couple of days back. The address is: ...

I have setup new PoA network with default block gas limit to 3 billions. The network starts with configured limit. However, overtime the block gas limit reduce down to 8 millions. Is there a way to ...

Is possible to run out of gas when calling bytes32[], even when count e.g. 1k entries?

I want to create my own pool where me and my bros can mine ETC (because it is not difficult) without fees. So, stratum and some others are done, only Front End and reward system left. I've checked ...

I want to populate my smart contract with data. I am using truffle framework. In migrations file for the smart contract I'm populating the data but it is giving error: TypeError: instance.create is ...

My question is rather simple, and I found this question in the Bitcoin StackExchange that somehow relates to mine, although, for the Bitcoin Blockchain, which I'm not sure if Ethereum solves the ...

I have created three node on three different machines. I have used same genesis file for all three nodes. Here is my screenshots of nodes Node-1 Similarly, I have set up two more node on two ...

I'm trying to send a private transaction using Quorum geth, but eventually got an error : Error: ether value is not supported for private transactions at web3.js:3143:20 at web3.js:6347:15 ...

This one: https://etherscan.io/address/0xc12d1c73ee7dc3615ba4e37e4abfdbddfa38907e As you can see most of the last transfer fail, the transfer function is: function transfer(address recipient, ...

Was wondering if there is already an open source solidity code with method to sweep erc20 tokens received in contract address to destination address by calling an in-contract method such as "sweep()". ...

I am currently trying to perform heavy load testing on a ERC20 token. My plan is to use truffle to test stuff like how long it would take for 500 transfer transactions to be deployed (on a private ...

I am trying to perform a heavy load and scalability tests on a smart contract. However, the test takes a lot of time because only 1 transaction is added per block. I read that this might be due to ...