All Questions
2,867 questions
50
votes
3
answers
31k
views
What is a sidechain?
The Ethereum subreddit has this post related to an Ethereum-Dogecoin sidechain.
What is a sidechain?
Could one sidechain be a private Ethereum network?
- 2,018
40
votes
2
answers
26k
views
How do I convert my The DAO tokens into ethers using the withdrawal contract after the hard fork?
The DAO contract was attacked on 17th June 2016 where the attacker drained about USD 50 million worth of ethers using a recursive call vulnerability in The DAO contract code.
The attacker drained ...
- 40.4k
36
votes
3
answers
24k
views
ERC20 vs ERC223. List of differences
Is there a list of improvements that we will have in ERC223?
Are there examples of contracts?
Is there a migration path for existing ERC20 tokens?
- 4,357
30
votes
3
answers
27k
views
If someone found a private key to 0x0, would they be able to access all the tokens (over one billion dollars worth) stored there?
The 0x0 address in Ethereum has a lot of token stored in it that have been burnt in the past. However, it appears they burning is the same as sending to 0x0. In that case, could all of those burnt ...
- 403
27
votes
5
answers
37k
views
Paying a transaction fee with an ERC20 token
As far as I understand, one of the ERC20 token's features is that you can pay a transaction fee with it. In other words, you can send them without having Ether. I transferred REP tokens to the ...
- 351
24
votes
3
answers
25k
views
How to infer token price from ethereum blockchain UniSwap data?
I would like (if possible) to infer a token price from the blockchain using UniSwap data.
After reading the following article, I understood that it is feasible:
https://blocklytics.org/blog/uniswap-...
- 467
21
votes
2
answers
15k
views
Is there length limits on Token Symbols?
Is there a limit on the length of a ERC20 Token symbol? I would like to use 4 letters, one of which is lower case, but that isn't an issue. My concern is if Exchanges have setup their tools to only ...
- 423
20
votes
2
answers
46k
views
Getting ABI data for ERC20 tokens programatically with Web3 [duplicate]
I am just starting to dive into Web3. I am trying to display the various ERC20 token values for a given Ethereum Address.
The pieces I need to do this are:
Token Contract Address
Token Contract ABI
...
- 8,078
17
votes
2
answers
40k
views
Decimals on ERC20 Tokens
I'm having an odd problem working with some ERC20 token contracts I've written:
When I specify a decimal value, let's say 4 here for simplicity, the values show up differently in Mist vs etherscan.
...
- 171
17
votes
5
answers
8k
views
How do you verify a contract on etherscan that is deployed by another contract?
How do you properly verify a contract on etherscan that is deployed by another contact?
I deployed a contract that deploys other contracts onto the blockchain.
The original contract is verified , ...
- 847
17
votes
2
answers
4k
views
What are the key criteria for meeting the ERC20 token standard?
I'm looking for a clear way to describe "the ERC20 token standard" to regular folks like me who are not developers, and can't seem to find a plain language articulation of the core components of that ...
- 2,279
16
votes
5
answers
26k
views
Send tokens using approve and transferFrom vs only transfer
We can send tokens using below ERC20 contract methods
approve() and transferFrom()
transfer()
Here if i use 2nd option the tokens are directly transferred, while if i use 1st option its a two step ...
- 161
16
votes
2
answers
10k
views
How do I convert my The DAO tokens into ethers on the Ethereum Classic chain?
According to Whitehat Withdrawal contract - Update and Next Steps and Whitehat Withdrawal contract - Last update before deployment, the Goodies will be deploying the withdrawal contracts whetcwithdraw....
- 40.4k
16
votes
2
answers
12k
views
How do I get a refund for the amount I paid in excess of 1 ether to 100 The DAO tokens
Anyone who bought DAOs in the last two weeks of The DAO crowdfunding phase paid more than 1 ether (ETH) per 100 The DAO tokens (DAO). The ETH amount in excess of 1 ETH per 100 DAOs was stored in The ...
- 40.4k
16
votes
3
answers
6k
views
Accepting an ERC20 Token as Payment
Assuming I have deployed my ERC20 token, and the supply has been dispersed, is there any method of creating a separate contract that accepts that ERC20 token as payment and has user fields that send ...
- 173
15
votes
2
answers
6k
views
what does `wad`stand for
in many token contracts the amount parameter is called wad
I was not able to make sense what this means or where it comes from. Does someone have a clue?
- 2,223
15
votes
4
answers
103k
views
How To Transfer Tokens Out Of Metamask Wallet
I have some tokens in my Metamask wallet and want to transfer them to an exchange to trade but I don't know how to do. Metamask now allows you to see the tokens as per the recent upgrade but I don't ...
- 161
15
votes
2
answers
3k
views
How can ERC20 token implementations be verified?
The ERC20 Token Standard is great, in that it allows wallets, exchanges, and client implementations to allow users to interface with a variety of tokens in a common way. But how can one of these ...
- 615
15
votes
2
answers
10k
views
Are ERC20 token names unique?
I am curious if ERC20 token names are unique on the Ethereum block chain? For example, what is to stop someone from creating a new token called Golem (GNT) and publishing it to a smart contract?
I ...
- 730
15
votes
2
answers
3k
views
ERC20 Tokens with Rewards?
How hard is it to implement rewards into ERC20 Tokens? By this I mean a ERC20 Token that receives a reward in the form of Ether from a rewardAccount that is distributed evenly between all tokens.
...
- 311
14
votes
3
answers
5k
views
Binance Smart Chain tokens: What are tTotal, rTotal, tSupply, rSupply, rOwned, tOwned which I see everywhere?
Looking at all the latest shitcoins' Smart Contract code on Binance Smart Chain, there's a lot of common,recurring themes because most of each project's code is mostly copy-pasted. The code is also ...
- 348
14
votes
1
answer
21k
views
how to get list of transactions history about specific contract address using web3?
I really don't know how to get a list of transactions history about specific contract address using web3.py
and I use Infura HTTPProvider
I just have only one 'contract address'.
Can i get information ...
- 143
14
votes
4
answers
15k
views
Solidity/Remix Error : The constructor should be payable if you send value. How to solve this?
pragma solidity ^0.4.16;
contract MyToken {
// This creates an array with all balances
mapping (address => uint256) public balanceOf;
// Initializes contract with initial supply tokens to ...
- 141
13
votes
3
answers
32k
views
Best way to burn ethers and other ethereum tokens?
Is it correct that any ethers or tokens sent to the address 0x0000000000000000000000000000000000000000 will be destroyed?
Or what is the best way of burning ethers / tokens?
- 543
13
votes
7
answers
23k
views
Where can I find ERC20 token faucets for testing?
I want to use the Ethereum test network to test token transfers and such, but I can't find any token faucet or anything like it so I can't try out things. Google didn't show anything, only Ethereum ...
- 443
13
votes
4
answers
18k
views
How can I find out the token balance of some address?
How can I find out the token balance of some address using Solidity?
For example, I have the address of another person, and I need to know the number of tokens on his account.
- 531
13
votes
2
answers
47k
views
How to get tokens out of a metamask account
I transferred tokens (GNT) from an exchange to a metamask account but I can't figure out how to get them out. They do not show up in metamask, but etherscan shows them. I tried to import the account ...
- 131
13
votes
1
answer
5k
views
What is the purpose of interface contracts?
Reading The DAO and DigixDAO source code I notice that in contract systems there are often interface contracts where functions are declared without any body.
For example,
contract TokenInterface {
...
- 1,298
13
votes
2
answers
12k
views
How do I send multiple transactions as one transaction?
Say I need a user to approve a contract with an erc20 token balance and then the contract can execute it's function after. Typically, I would have to do an approve transaction with a nonce of 1 and ...
- 426
12
votes
4
answers
16k
views
A list of token holders at a specific time
What's the best way to get the list of token(ERC20) holders with their balance at a specific time? Thank you.
- 121
11
votes
4
answers
32k
views
How to transfer ERC20 tokens using web3js
I've read some docs, run parity in docker container, and being
able to connect and get token balance of an account
const Web3 = require('web3'),
const web3 = new Web3(new Web3.providers.HttpProvider('...
- 111
11
votes
3
answers
3k
views
How to remove custom tokens from mist?
In the MIST wallet (0.5.2) I somehow managed to create a Watch Token contract which was not correct and then it showed up like this: the one in the middle.
It is greyed out and I want to delete it, ...
- 113
11
votes
4
answers
18k
views
ethminer Failed to submit hashrate
I keep getting an error: ethminer Failed to submit hashrate :(
I am very new to this whole mining thing, and just want to learn more.
I am using:
Geth
Version: 1.5.0-unstable
ethminer version 1.2.7
...
- 133
11
votes
1
answer
4k
views
Sign raw transaction offline with C++ on arduino
I'm exploring the IoT side of the EVM. I've programmed Arduinos and ESP8266s to interact with a Geth JSON RPC. I'm trying to be minimalistic and avoid NodeJS on the Geth JSON server side. Currently ...
- 441
11
votes
1
answer
2k
views
Can an Ethereum address hold more than Ether?
Let me explain it with examples. On Bitcoin protocol, for example, you have Counterparty. As it uses embedded consensus, every XCP address is linked to a Bitcoin address. So if you hold bitcoins on ...
- 221
10
votes
2
answers
15k
views
Why most ERC-20 Tokens Have 18 Decimals?
I don't really understand the fundamental rationale for this. I'd think 0 decimal is much simpler to understand for most people?
- 461
10
votes
4
answers
14k
views
How to decode input data from tx using python3?
I am trying to decode input data from token sale transactions. This is one of the transactions I am trying to parse 0xf7b7196ca9eab6e4fb6e7bce81aeb25a4edf04330e57b3c15bece9d260577e2b
Which has the ...
- 173
10
votes
3
answers
17k
views
What does it really mean to burn tokens?
I don't quite understand what it really means to burn tokens. Since the blockchain is immutable, there should be no way to delete the record. Thus, in my understanding, to burn the token merely ...
- 373
10
votes
2
answers
4k
views
What is the best way to handle multiple NFTs of the same collection in ERC1155?
I'm learning ERC1155, and I'm a bit confused.
This is OpenZeppelin's example of an ERC1155 Contract:
They state that Thor's Hammer is an NFT (because only 1 was minted), while Gold is Fungible.
...
9
votes
3
answers
7k
views
Convert an eth key to a geth key
I need to convert my eth key to a geth key.
eth put the key in %appdata%\roaming\Web3\keys, and I see it as a .json file. If I move that to the %appdata%\roaming\Ethereum\keystore directory, geth ...
- 93
9
votes
2
answers
2k
views
Float not allowed in solidity vs decimal places asked for token contract
We know that solidity doesn't support the float values. But here (https://www.ethereum.org/token#understanding-the-code) they accept one input parameter 'decimal places' for calculation purpose. How ...
- 3,545
9
votes
6
answers
13k
views
Doing a bulk transaction with my ERC20 token (How to do it)
I was wondering if someone has more information on how to do a bulk transaction on the Ethereum network for ERC20 tokens.
Let's say I need to send 1 ethereum to 10 users or 10 ERC20 Tokens for that ...
- 91
9
votes
1
answer
2k
views
ICO crypto-currencies accepted during the sale: ETH, BTC, or even fiat?
ICO contracts are meant to accept Ether as payin for the tokens sold, for example https://cartaxi.io/pre-ico or https://www.herocoin.io/
But there are a lot of ICOs running on Ethereum that accept ...
9
votes
2
answers
11k
views
How can I watch tokens in Parity wallet?
I love the Parity Ethereum wallet. It works very well. But I assumed it would automatically show any tokens I own if I watched contract that held the tokens.
For example if I watch singularDTV ...
- 10k
9
votes
2
answers
8k
views
Get smartcontract token balance via JSON RPC
Via Geth commandline I can get my smartcontract token balance with:
var mytest = eth.contract([{interface}]).at(contract address);
mytest.balanceOf(eth.accounts[0])
>998
I want to present the ...
- 191
9
votes
1
answer
193
views
What will happen to legacy smart contracts when Ethereum 2.0 is released?
Most importantly, ERC20 and ERC721 tokens. Will they be migrated to the new chain? Will migration only be optionally possible for contracts with an owner? What about contracts which rely on proof of ...
- 191
8
votes
3
answers
6k
views
CPU mining JSON_PARSE_ERROR
I just wanted to mine ETH with my CPU. I use Windows 7 64 Bit with ethminer.
I started the cpu miner with a batch
ethminer -t 6 -C -F http://ethereumpool.co/?miner=5@0x17C0Bea7c44*******...
- 161
8
votes
2
answers
9k
views
Why does my smart contract tokens not show up in MyEtherWallet or MetaMask?
I have deployed a very basic smart contract to the Rinkeby test network. The contract's address is 0xb145b6d8757b40ac80b5fe2a98ab6c8450a54585. I have made transactions to it using MetaMask, and they ...
- 564
8
votes
4
answers
12k
views
web3.js can I call a smart contract function without knowing the ABI?
In a web3 JS dApp (eg.with Metamask),
If I know just the address of a contract and the method name, how can I call that method ?
I don't know the ABI.
- 911
8
votes
3
answers
3k
views
Can I sell a portion of my DAO tokens on a market place?
If I bought all my DAO tokens with the same account, will I be able to sell only a portion of them on a marketplace?
- 10k