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89 votes

Is Ethereum wallet address case sensitive?

Ethereum wallet addresses are in hex [0-9A-F]*. While the address itself is case-insensitive (A is the same as a to the network), the case sensitivity is used as a (optional) checksum. It was built as ...
knocte's user avatar
  • 1,949
52 votes

How can I check if an Ethereum address is valid?

There is an easier way now with web3: Naive: https://web3js.readthedocs.io/en/v1.2.0/web3-utils.html#isaddress web3.utils.isAddress('0xc1912fee45d61c87cc5ea59dae31190fffff232d'); > true OR ...
rstormsf's user avatar
  • 4,357
37 votes
Accepted

How do I convert my The DAO tokens into ethers using the withdrawal contract after the hard fork?

Update Mar 29 2017 The latest instructions can be found at The DAO Refunds. Notes This Withdrawal contract only allows the conversion of The DAO tokens (DAO) into ethers (ETH) at the rate of 100 ...
BokkyPooBah's user avatar
  • 40.3k
36 votes

How to convert WEI to ETH with ethers.js

Take a look a formatEther in the ethers.js documentation const weiValue = 100000; const ethValue = ethers.utils.formatEther(weiValue); You can also format an arbitrary amount of Wei into any other ...
Codey's user avatar
  • 461
33 votes

How to get ETH contract balance with Ethers.js

getBalance is a function of the Ether.js blockchain provider object, it is used this way : const balance = await provider.getBalance("address"); Note that you can use contract.address to ...
clement's user avatar
  • 4,322
29 votes

Gas price in ETH unit

There is no fixed gas price that transactions must have. You can specify the gas price, and if you set a gas price within certain bounds, the transaction will be accepted by miners using their ...
eth's user avatar
  • 86.1k
29 votes

ethers formatEther(wei) with max 4 decimal places

As you said const {utils, BigNumber} = require('ethers'); const balance = BigNumber.from('824213281784279560'); console.log(utils.formatEther(balance)); gives 0.82421328178427956 as string. You can ...
Diego Ferri's user avatar
24 votes
Accepted

Can a contract with no payable function have ether?

Yes, a contract can have Ether balance without any payable function. There are four ways how it's possible: selfdestruction. Another contract self destructs (by using the selfdestruct functionality) ...
Lauri Peltonen's user avatar
21 votes
Accepted

What is Ethereum's inflation rate? (how quickly will new ether be created)

The question is What is Ethereum's inflation rate? , but I'm assuming and answering the question What is the issuance rate of Ether. The short answer In 2017 the issuance rate of Ether is 14.75%. ...
Samuel Hawksby-Robinson's user avatar
20 votes
Accepted

are there "public" ethereum nodes? or any recommendations on hosting solutions?

Infura is the most prominent public Ethereum nodes. They run mainnet and many of the testnets. They also run IPFS servers. http://infura.io.
Thomas Jay Rush's user avatar
19 votes

Why is ether divisible to 18 decimal places?

I do not know for sure, but it makes lots of sense that if doing fixed precision arithmetic, 18 decimal places is exactly the amount of precision that fits in a 64 bit signed long when storing the ...
random internet person's user avatar
19 votes
Accepted

Where does the consumed ether/gas go?

Gas is paid for out of the sender's ether balance, at the rate specified by the chosen gas cost. Any unused gas is refunded, and consumed gas is credited to the miner who mined the transaction, again ...
Nick Johnson's user avatar
  • 8,174
19 votes

Insufficient funds for gas * price + value

It seems to be a bug in geth, try the solution presented here : https://github.com/ethereum/go-ethereum/issues/2173 they assume that the solution is : Convert all values to hex (with bc if you use ...
Badr Bellaj's user avatar
  • 18.8k
18 votes

How do I backup my ether accounts?

PLEASE MAKE SURE TO ALSO BACKUP YOUR PASSWORDS Each key file (as described in @Ethan's answer) is encrypted and only usable with the correct password. Another safety tip: Before deleting any key ...
eth's user avatar
  • 86.1k
18 votes
Accepted

What prevents the market from assigning value to testnet ETH?

The testnet can be reset any time by the Ethereum developers by issuing a new default genesis block. New testnet nodes would run automatically the new testnet. Therefore people do not build any ...
Roland Kofler's user avatar
18 votes

How to get ether on public testnet?

The 2 best ways I found were: 1) Instant: an ether faucet here: http://faucet.ropsten.be:3001/ 2) An hour or two: Switch on Mining from the menu Develop > Start Mining (Testnet only) or Command ...
Benc93's user avatar
  • 393
17 votes
Accepted

What is the smallest amount of Ether?

The smallest unit of ETH is called Wei, and is 1x10^-18 ETH, i.e. 1 Wei = 0.000000000000000001 ETH
Tjaden Hess's user avatar
  • 37.2k
16 votes

What is the total supply of Ether?

From StephanTaul on the Ethereum Forums on September, 2014: There is no maximum. 60,102,216 ethers were created during the sale, plus 2x pools of 9.9% each. 26% of 60,102,216 will be created through ...
tayvano's user avatar
  • 16k
16 votes

How to get ether on public testnet?

you can get ethers on the testnet simply by using Metamask plugin. here's how: You need beforehand install metamask plugin from here, then follow the steps shown in the following picture : 1-press ...
Badr Bellaj's user avatar
  • 18.8k
16 votes
Accepted

Testing Error thrown with hardhat

When I test a function for revert I do the following in my javascript test file (e.g. myContractTest.js): const { expect } = require('chai'); const { ethers } = require('hardhat'); const { BigNumber } ...
Majd TL's user avatar
  • 3,237
15 votes

Is there any Ether mixer / tumbler available?

Philip Kirkbride's answer is misinterpreting cryptographers' use of obfuscation, and is also wrong. Mixers cannot be 'decoded' with any feasible amount of computing power. 'Decoding' the input-output ...
bekah's user avatar
  • 1,099
15 votes

What is the size (bytes) of a simple Ethereum transaction versus a Bitcoin transaction?

This post contains several questions. Let's address them one by one. Before answering the questions, there is an error in the post's assumption: it doesn't consider the transaction fees. If Alice has ...
Linmao Song's user avatar
  • 2,357
14 votes
Accepted

How fast should be an internet connection to mine ETH?

How fast should be an internet connection to mine ETH? I'm currently on a ~ 10 Mbits/s download and 1 Mbits/s upload line and it is fast enough to mine the Ethereum blockchain while performing my ...
BokkyPooBah's user avatar
  • 40.3k
14 votes

What's a fallback function when using address.send(...)?

Yay, found it in solidity docs in FAQ section: What is the deal with function () { ... } inside Solidity contracts? How can a function not have a name? This function is called “fallback ...
manidos's user avatar
  • 4,298
14 votes

send ethers from one contract to another

Send Ether to your contract (ethertransfer) from the external account (a term for user controlled accounts). To be able to make it, you need to have a payable function in your contract (which might be ...
Lukasz Zuchowski's user avatar
14 votes
Accepted

How to divide 11 wei by 2?

The result of 11/2 in Solidity is 5, because there are no floating point numbers so the decimal is truncated.
natewelch_'s user avatar
  • 12.2k
14 votes
Accepted

How do you send Ether as a function to a contract using Remix?

The code is correct but I lacked the understanding regarding the mechanics of how Ether is accessed and sent to contracts. I will explain to aid others in their advancement of knowledge... The ...
29A's user avatar
  • 347
13 votes
Accepted

Is any way to withdraw ether from a smart contract to owner wallet, if no such method in it?

No. Unless you have a self destruct / suicide function, or a way to transfer ether, there's no way to get ether out of the contract. This is by design: if there were an automatic "escape hatch", ...
Nick Johnson's user avatar
  • 8,174
12 votes

What prevents the market from assigning value to testnet ETH?

Testnet ETH is practically infinite. The Morden genesis block allocates one address, 1.6e42 Ether. Some Ethereum developers know the private key to this and its primary use is for faucets. Here's ...
eth's user avatar
  • 86.1k
12 votes

TheDAO hack FAQ: How did the attack happen on 17 June 2016?

What happened? 3,641,694 ETH where splitted out of theDAO. The attacker found a loophole in the regular splitDAO function so that they could reuse the same DAO tokens over and over again. How ...

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