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1500 questions
10
votes
1 answer
Whisper V6 vs Whisper V5
Could some one please
summarize the differences between V5 and V6
tell us where to find documentation - I could not find any although I understand this is in EIP 627
is it "production ready" ?
say whether the Go implementation in Geth is forward…
Bruno Grieder
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10
votes
3 answers
Substring in solidity
I am looking for a way to get substring of a String. I am looking for an equivalent of this Java method. I am ok to use libraries but did not find it in solidity-stringutils.
public String substring(int startIndex, int endIndex)
Titu
- 379
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10
votes
5 answers
How to check if a contract has a method?
Given a valid contract address how can I check if the contract implemented a certain interface i.e Ownable?
c.sokun
- 267
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10
votes
1 answer
Non Deterministic External Service Call
As per the basic rules of blockchains believe it is mentioned that no service call from the smart contract should be made where the result is non deterministic.
What I understand is if the result is non deterministic in that case, when the…
Susmit
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10
votes
1 answer
contract.at is not a function
I'm learning about ethereum and smart contracts and I have a simple contract that stores a string. I'm trying to use web3js to change that string. I'm having trouble following the instructions from this answer…
Hjelmut4
- 103
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- 4
10
votes
4 answers
Adding Wallet using web3.eth.accounts.wallet.add
On web3 0.20.1, I am using Infura to deploy a contract to Rinkeby. This probably requires me to add a wallet to web3.accounts to provide the gas needed.
When I ran the following nodejs code,
Web3 = require('web3')
var web3 = new Web3(new…
Nyxynyx
- 1,167
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10
votes
2 answers
What is the execution order of Inherited constructors in solidity?
I'm reading the section on inherited constructors on the documentation here.
The example given confuses me than understanding the concept, and it doesn't explain the most important part, the execution order.
To summarize the documentation, it says…
Vlad
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10
votes
1 answer
geth: config file documentation
I'm trying to use geth --config to start geth.
My config file contains:
rpcport = 8555
networkid = 3
I get:
Fatal: /home/ravi/.ethereum/config-test, line 1: field 'rpcport' is not defined in main.gethConfig
Where do I find the the list…
Tom Hale
- 3,107
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- 20
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10
votes
2 answers
How to do Ethash CPU mine using ethminer?
I have a Private Ethereum Network. I just want to do Ethash CPU mining using ethminer. I know that to have a smaller foot-print it is recommended to use GPU or openCL but for private networks, I only have few nodes on the network and all are CPU…
alper
- 8,395
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10
votes
3 answers
Where to find contract ABI in new version of online remix solidity compiler?
After the online remix solidity compiler recently changed design, I can't figure out where I can find the contract's ABI? Does anyone know where it can be found in the new version? Or any other way where I can get it?
https://remix.ethereum.org
fech
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- 2
- 9
10
votes
3 answers
How would stablecoins work on Ethereum?
The idea of a stablecoin in Ethereum is to create a token that is pegged to the price of say $1 USD.
What are the main ways of achieving a stable cryptocurrency? What DApps are implementing them and how are their approaches different?
eth
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10
votes
1 answer
do the contracts of ethereum have the access to the nonce of the blocks?
by this question I mean when we try to develop a gambling game contract we need some random input, can we just use the nonce data from some certain blocks?
(I just start learning blockchain, I'm from China, there may be some language problems about…
Wang
- 2,416
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- 19
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10
votes
1 answer
What determines transaction costs (Remix)?
I've reviewed several related SE questions on this topic and I haven't seen an answer. In Remix, I've created two separate .sol files. The files are names file1.sol and file2.sol. The code for the two files looks like this:
file1.sol
pragma solidity…
Some User
- 285
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10
votes
4 answers
What's the best way to transform bytes of a signature into v, r, s in solidity?
Given that solidity does not have any built-in string/bytes manipulation library, I was wondering what the best practice for extracting v, r, s from a signature inside solidity is.
One can encode sig as string v-r-s and use solidity-stringutils to…
d9ngle
- 436
- 4
- 10
10
votes
2 answers
Storing private data on the ethereum blockchain
I plan to make an app utilising Ethereum that will store private data about a user. Eventually, I want this data to be accessible by selected users.
I have seen conflicting answers & discussions on various threads on SE, reddit, and, other articles…
joe
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