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How to use my IOS skills into Crypto Currency

I know this is not an appropriate question in this technical forum. However, I would like to know how to utilize my IOS skills in this emerging Crypto world. I have 5 years of experience in IOS tech ...
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0answers
2 views

Miners are not working when running geth command in background in linux

I am running my private blockchain using geth on my ubuntu server with following cmd then its working fine geth --datadir ~/chaindata/ --networkid 45123 --verbosity 3 --rpc --port 30304 --rpcport ...
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0answers
5 views

How to add member NOT peer node to private ethereum network

I followed this parity-poa tutorial to build a private POA ethereum network in local. I want to add member node to this network . so i run parity client with below configuration toml file: [parity] ...
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0answers
3 views

'Contract' object has no attribute 'eventFilter' web3.py

I am trying to filter Transfer events from my local ethereum node using web3 py. I have created a venv in visual studio code. My code is as follows: def decodeLogswithfilter(t1, t2, abi1, addr): ...
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1answer
11 views

Is it possible that an Ethereum Address starts with 0x0

Is it possible that an Ethereum Address starts with a 0 on the first place after the hex prefix? For example: 0x0c01a1da70b4109be8789af5fd678183145dbe55
1
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1answer
36 views

How does miners vote to determine the block gas limit?

In many posts people say "miners periodically vote to determine the block gas limit". But how actually do they vote and change the block limit? Do they vote for every block/or do it every day or for ...
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0answers
20 views

web3 returns wrong uint256

I have a contract that implements the following function: function getVehicles(address _addr) public view returns(Vehicle [] memory) { return addres_vehicles_map[_addr]; } I have ...
2
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1answer
15 views

Ethereum in space?

Have there been any missions that have launched an Ethereum blockchain into space? I know there's a satellite that transmits the Bitcoin blockchain to anyone that pings it -is there anything similar ...
1
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1answer
12 views

why does not shown the holders number and transfers of the custom ERC20 token in Ropsten?

I published an ERC 20 token on Ropsten. The token's total supply, name and symbol shows on the self page (https://ropsten.etherscan.io/token/..) but the holders number and transfers are not shown. The ...
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1answer
19 views

Provable API for calling ETH-USD price in a contract

This contract is hosted at https://github.com/provable-things/ethereum-examples/blob/master/solidity/truffle-examples/kraken-price-ticker/contracts/KrakenPriceTicker.sol I have made the constructor ...
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0answers
19 views

How can EVM tracer REVERT at depth == 1, then continue successfully?

I'm observing fault() (and step() with log.op.toString() == 'REVERT') with log.getDepth() == 1 in a tracer, followed by another step() instruction. (getTransactipnReceipt() shows status: 0x1, and ...
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0answers
6 views

how to find correct path using loadScript in geth when attaching localhost

I get a false returen when I start geth and try to load a script $geth attach http://localhost:8546 when I connect to parity client and I try to load a script loadScript("./scripts/addresses.js") ...
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0answers
36 views

How to generate unique id for each tokens without using loop?

I'm creating tokens without use of any pre-defined standard. As we have requirement to track each token, I did code to assigned ids to each token. pragma solidity ^0.5.0; contract MyContract { ...
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0answers
14 views

How to process includes in a .sol file?

How to process all includes in a .sol file? I want to produce a file with all includes recursively replaced with the included files content.
0
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1answer
10 views

Etherscan api: how to get transaction fee?

For example: open this https://etherscan.io/tx/0xcb1e3530950cf2c43a307bcb5645ae71a12c76a60831617badd04aea3efe68aa It's a random one I see these infos on webpage: Gas Limit: 136,500 Gas Used by ...
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1answer
14 views

Transactions Stuck. Offline transaction cancelling is not working either

Transaction is stuck pending, so I used Myetherwallet to generate an offline transaction with the same nonce as the pending transaction, YET once the transaction is posted, I see that the nonce ...
0
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1answer
13 views

Error Initiating Web3

I am having an issue initiating Web3. For web3.setProvider(), web3.eth.accounts.create(), etc., I receive the error: "Cannot read property 'setProvider/accounts/deployed' of undefined". I am using ...
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1answer
22 views

This is user verification code, I'm unable to understand this code

The below code of solidity is for user identification. I need help in understanding the code.
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0answers
10 views

Two or more address sender same transaction

Can a Ethereum transaction has two or more address as senders like Bitcoin transactions? My idea is use a smart contract to assign a transaction with two or more address, i.e. thinking in a ...
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0answers
13 views

Truffle Object Keeps Changing to Undefined When I Try To Play With Data With React

The question is in the title. I have a React Component that displays the appropriate data when I do it in a very specific way, but breaks when I try to play with the data. state = { dataKey: "1",...
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1answer
33 views

smart contract for fair exchange

Question: Is it possible to create a smart contract for fair exchange and investment: user1 sends ether to a smart contract which will multiply the amount by 2 and send it to user2. When user2 ...
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0answers
6 views

I am having issues running truffle test and keep on getting “No events are emitted” ERC20 Token. How can I fix this?

This is my DappToken.sol pragma solidity >=0.4.17: contract DappToken { string public name = "Token"; string public symbol = "TOKEN"; string public standard = "Token Version 1"; uint256 ...
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2answers
7 views

What causes .deployed() to return same contract instances in each test

It took me awhile to diagnose the problem. At first I just noticed that the states of my contracts were being affected by previous tests when running truffle test I then looked in the terminal tab in ...
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0answers
7 views

Why does not show my token balances and the other information it on Ropsten?

I published an custom ERC20 token contract in Ropsten network and functions are working of the contract correctly. I minted the 100 token to an address an checked total supply result is 100 too. And ...
1
vote
1answer
12 views

What's the max number allowed as nonce?

I tried to generate nonce using this formula, so I can avoid 'underpriced' problem and nonce conflicts nonce: web3.utils.toHex( Math.round (Date.now() / 1000 - 1586000000) ), But simply these ...
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0answers
7 views

When is a “shard block” cross-linked into a “finalized beacon block”?

In Ethereum 2.0, a shard block for being finalized needs to be linked into a finalized beacon block. Under which conditions a "shard block" cross-linked into a "finalized beacon block"? Having 2/3 of ...
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0answers
11 views

setBill function isnt affecting the values

a beginner contract developer here pragma solidity ^0.5.0; contract waterBill{ address admin; uint public rateperliter; struct Individual{ string name; string addr; ...
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1answer
18 views

Read data from VIEW function on deployed contract

I'm trying to read some data from VIEW function on already deployed contract using my own smart contract. The function is standart "balanceOf(address)" of ERC20 token. I can read this data using ...
0
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1answer
12 views

web3js: Can I send a signed Transaction without wait the result?

Commonly, I dow const receipt = await web3.eth.sendSignedTransaction(web3, signed_transaction); console.log("tx_hash:", receipt.transactionHash); console.log("gas_used:", receipt.gasUsed); console....
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1answer
18 views

Ethereum Parity is stable ~800 blocks behind

I can't get up-to-date with Parity. Real blockchain height is near 9831752, Parity is pushing 9830795 currently, and Qed is 9831228. Initially downloaded blockchain using warp mode two ...
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0answers
11 views

Access latest transactionHash in other miner

For example, I have 3 miners in my private network. Let's just say minerA, minerB, and minerC. So, there's a transaction going on between minerA and minerB. Is there any way that minerC can get the ...
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0answers
2 views

Chain Transactions Together on Metamask Mobile

So, I have to approve a transaction on one contract and then I have a chained promise call to initiate a transfer onto another separate contract. Works just fine on Metamask Desktop, but on the ...
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0answers
7 views

Chain Transactions Together on Metamask Mobile

So, I have to approve a transaction on one contract and then I have a chained promise call to initiate a transfer onto another separate contract. Works just fine on Metamask Desktop, but on the ...
0
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0answers
9 views

Proper way to fire smart contract function passing an array with web3js

I'm using web3js version 0.20.7 The smart contract originally had a function (called whiteListAddress(address _address, bool value) ) that took an address and a boolean value, which was called like ...
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1answer
14 views

Eventhough function is declared payable , getting this error:The called function should be payable if you send value

I am new to Solidity and can't understand why I am getting the above error even though the function purchaseProduct() is declared as payable. I tried this code on Remix IDE and got this error. VM ...
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0answers
5 views

I sent my USDT money to my address in the ETH wallet

I have sent USDT money to my ETH wallet address by mistake how do I get a refund This is my ETH wallet address 0x0fD6b2B791Ab01e13D540c2942dba0ee810A4F93
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0answers
9 views

What is a pending transaction?

I tried to send a signedTransaction using a low gas price (it's my will to test timeoute of my scripts) I supposed also that a not mined transaction was 'pending', so I tried checking, while the ...
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0answers
9 views

Chain reorganisation: How often one confirmation transactions do not end up to the first block the wallet thinks

Currently web3.js wallets like MetaMask work so that they return the transaction receipt to the dApp as soon as the Ethereum node, connected internally by the wallet itself, sees one confirmation for ...
1
vote
1answer
9 views

How to add gas to a Truffle generated account imported to MetaMask

I am a beginner and was building a dapp using truffle unbox react. In my app, I was just taking input of a string and printting it using a simple contract. Everything is working fine. But, when i ...
1
vote
1answer
15 views

How to calculate current DAI Savings Rate

I have read the documentation on the topic but still don't get how I can calculate the current DAI Savings Rate myself. The current dsr value is stored in the pot contract. At time of this writing it ...
0
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0answers
9 views

yellow paper: identifier for the final state

I've started to read the yellow paper and in section 2 it's written: Blocks function as a journal, recording a series of transactions together with the previous block and an identifier for the final ...
1
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1answer
21 views

Is it possible to send ERC-20 tokens with the gas from another account?

I'm creating a DApp platform which allows customers to send and receive USDT (ERC-20 Token). The problem I have is that if customer want to send some Tethers out, he should have enough ETH too as the ...
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0answers
11 views

Fastest way to convert private to public key in C# .net?

For vanity reasons I am trying to find a private key whose public key has the same 4 characters in both the start and ending position, such as: 0xABCD_____________ABCD . I am finding that my computer ...
1
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1answer
17 views

What is the difference between the constant and immutable keywords in Solidity?

What is the difference between the constant and immutable keywords in Solidity and how do I use them?
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0answers
8 views

The problem of not showing my money in the wallet [closed]

My friend sent me the USDT money but I was surprised that the blockchain wallet does not accept that How can I solve this problem?
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0answers
17 views

ERC721 Token abstract contract or an interface and cannot be deployed

after reading many post i can't found the issues about this Smart contract who compile but it think i miss something about the inheritance and the Abstract contract. This is the SC : // solium-...
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0answers
12 views

If I set unlimited gas in a dev environment, am I just postponing dealing with a problem in my contract or is it a Truffle issue?

Booted up ganache with this command: ganache-cli --gasLimit=0x1fffffffffffff --allowUnlimitedContractSize -e 1000000000 because I was running into this error on truffle migrate in my development ...
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0answers
10 views

intrinsic gas too low in Ropsten

I am trying the sendSignedTransaction in Ropsten and I assigned the value of gas limit and gas price: gasLimit: web3.utils.toHex(21000), gasPrice: web3.utils.toHex(web3.utils.toWei('10', 'gwei')) ...
2
votes
1answer
55 views

Why is there a SHA256 pre-compiled contract when SHA256 is also an opcode?

The question is in the title :). Trying to understand why there is both an opcode and pre-compiled contract for SHA256. To execute the computation, would people canonically "CALL" into the pre-...
0
votes
1answer
15 views

Smart Contract Deployment Failed powershell

a beginner smart contract developer here, this is my smart contract pragma solidity ^0.5.16; contract Ballot { struct Voter { uint weight; bool voted; uint8 vote; /...

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