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Generating random number with Solidity (Chainlink?)

Hello I'm well aware there are plenty of threads around discussing different methods. Just curious and wanted to ask directly here because feel like the situation might be different. Essentially I'm ...
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2answers
14 views

How do i retrieve Eth from a contact that i created?

New to blockchain.. havent a clue.. I managed to create a new contract with Eth. I moved money from MyEtherum Wallet to Metamask and into a contract, somehow? I have no coding experience but need ...
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1answer
10 views

Attach to tessera node failing

Im installed quorum with tessera but when i need to attach to any node using command $ ./attach.sh 1 show error "Fatal: Unable to attach to remote geth: dial unix qdata/dd1/geth.ipc: connect: no ...
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1answer
12 views

A sweeper bot knows one of my ETH private key. What should I do?

I had a private key which I accidentally pasted on a group instead of pasting it on my notes (yeah it was dumb). Fortunately, I expected someone managed to save it even though I deleted it in an ...
0
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1answer
14 views

What is the cost of inter-contract calls?

I have a contract with methods to create items and add them to categories. I want to create a wrapper contract that would combine several calls into one: create an item and add it to several ...
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1answer
5 views

When a contract calls other contracts, is it an atomic operation?

If a contract calls several external methods of other contract(s), is it as a whole one atomic transaction (reverted as a whole if an exception happens)?
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0answers
9 views

{“jsonrpc”:“2.0”,“id”:83,“result”:“0x0”}

if my geth is syncing in fast mode and I try to query method eth_blockNumber, will it throw me an error, cause it is not, i tried curl in verbose mode and below is the result. * Trying 127.0.0.1... *...
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0answers
9 views

Obtain all token transactions

I need to be able to retrieve all transactions that happened in a certain time period for arbitrary token on ethereum network. What is the proper way to do it?
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0answers
6 views

web3.eth.accounts.wallet.create() works on desktop Chrome but not on mobile

The following lines of code work (a generator function of redux-saga in my React app) on desktop Chrome. However, it does not work on desktop Safari, iOS, and mobile Chrome (on Android). Did not works ...
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0answers
14 views

How can know which is library's bytecode?

When I compile solidity file that has more then two contracts, Solc gives me some binaries. That binaries include bytecode of library. How can I know which one is library's bytecode if I don't have ...
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1answer
100 views

Is Solidity being replaced as the de facto standard for smart contract development?

Is Solidity being replaced by languages such as Rust or other programming languages for smart contract development?
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1answer
16 views

Which method is efficient to log data in blockchain? Send an event via smart contract or send data in a transaction without value?

I want to log data in Ethereum block-chain. It is obvious that we can create a smart contract that emits events and retrieve data from it. But is sending a transaction with data but no ETH value (just ...
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0answers
21 views

Can a new deterministic address be generated with only an Ethereum public key?

BIP-32 defines a way to generate a new address with only knowledge of only the public key for that wallet Deterministic wallets ... permit schemes where one can calculate the public keys without ...
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0answers
15 views

What is the procedure for REP owners for migrating to Augur v2

What do REP holders need to do to preserve all of their rights after AugurV2 goes live? What period of time is provided for these actions?
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0answers
8 views

Cost to cancel or change an unfilled Augur order

With the launch of Augur v2, what is the cost to cancel a previously entered order that has not yet been filled? Is this cost the same as the cost to modify the order by changing the bid, ask or ...
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0answers
8 views

Augur v2 trading fee relation to Open Interest

How does the fee paid by traders to reporters relate to Open interest in Augur v2?
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0answers
14 views

How to debug this metamsk error ? - Error: [ethjs-rpc] rpc error with payload:

I have a DApp integrated with metamask and ganache, front-end built on react. I am getting this error when I interact with the smart contract from front-end, contract send calls. Smart contract ...
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0answers
18 views

Can a contract execute multiple signed transactions as one?

Say multiple signed transactions have been created and signed by multiple different accounts with web3.py or similar, is there any way to get them executed as a single transaction in Ethereum so they ...
0
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1answer
19 views

Error when retrieving the instance of a deployed contract

I have developed a EnergyExchange DApp in the Ganache local network with React that consist of one main contract "EnergyExchange". This main contract has a function to deploy new Agent ...
1
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0answers
13 views

Ethereum peer to peer load balancer

Is there any existing TCP load balancer product that is enode aware?
0
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1answer
12 views

Error when calling a get function from a deployed contract instance

I have developed a EnergyExchange DApp in the Ganache local network with React that consist of one main contract "EnergyExchange". This main contract has a function to deploy new Agent ...
0
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0answers
12 views

How to connect local private geth nodes to the web page without using metamask or mist?

I'm developing a web wallet similar to meta mask that can make transactions or can create accounts from UI. Frontend is developed using React. Blockchain is implemented in geth.I'm using truffle react ...
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0answers
12 views

Is not dai token loss for the minter?

I think that dai token of makerdao is loss for the person who mints, for example the collateralization ratio is 150%, so the person who mints has to pay 1.5$ worth of eth for 1$ worth of dai. If he ...
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0answers
30 views

When to use “memory” and “storage” keyword in solidity 0.6.0?

From what I've learned and noticed. Please add more point and rectify me if I'm wrong. Use of memory keyword 1)When initialising/declaring Struct, Array , and mapping. 2)In the parameters of functions ...
0
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1answer
17 views

how to check instantly when a user charges amount to his address generated by our app

Our app needs to detect and create a charging order asap whenever a user charges an amount of ETH/USDT(ERC20). Due to the limit of infura API, we decided to set up our own ETH nodes and use JAVA to ...
0
votes
1answer
18 views

Error in code Expected pragma, import directive or contract/interface/library definitio

I am getting the below error when i compile the below code. Using remix compiler version 0.5.11 ****browser/TodoList.sol:7:2: ParserError: Expected pragma, import directive or contract/interface/...
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0answers
29 views

How to estimate gasLimit of ERC20 contracts in web3.php project?

I am using web3.php project in my Ethereum based project. A part of this project is sending ERC20 tokens, and in this regard, I need to estimate gas limit of transaction. For this purpose, I found the ...
1
vote
1answer
33 views

what replaces assigning array.length to 0 for clearing it [duplicate]

I'm trying to follow the tutorial here and there's a line where an address array players has this done players.length = 0 which issues this error: member length is read-only and cannot be used to ...
0
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0answers
16 views

send 20 etho during live ethereum 2.0 [closed]

I send 20 ethen to the following address 0x3802b5311c99845fc41c31a0ca99a27f7ba2042d but receive nothing back to my address. I see the address report on etherscan not match with my actual receive ...
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0answers
15 views

how to send transaction without private key ganache?

I need access to oracle accounts (whose private keys i do not have) to test my contract. I'm trying to use ganache to fork my local node with the accounts unlocked through the ganache api, but ...
0
votes
1answer
27 views

How to save the contract instance on a mapping in solidity?

I have created an EnergyExchange contract in my React app.js that it is deployed in the network. Inside the EnergyExchange contract there is a function to create Agent contracts. What I am trying to ...
0
votes
0answers
8 views

Connecting geth and openethereum on a private network

Private network, running geth 1.9.15 and openethereum 3.0.1. Parity converter was used to create the chain.json file for openethereum. The two node show the exact same: genesis block network id ...
0
votes
1answer
11 views

What are variables defined as functions in the abi?

I was experimenting with this simple contract on a test network: contract HelloWorld { string public message; constructor(string memory initMessage) public { message = initMessage; } ...
0
votes
1answer
9 views

Do we need to create raw transaction for every UTXO that we use during a transaction?

Let say I have 2 UTXOs, one has value = 0.0001 and another one has value = 0.00005. Now I want to send 0.00014. SO now I have to use both UTXO to perform transaction. So do I have to create 2 raw ...
0
votes
1answer
7 views

What is the equivalent of “buildTransaction” of web3Py in web3JS?

I'm using Node to interact with my smart contract. I understand that I need to first sign my transaction before sending it. In one of the StackExchange answers I see that it can be done using ...
1
vote
1answer
17 views

Why fallback function cannot be declared public in solidity?

When declaring fallback function we needs to make sure that it is declared external but why fallback function cannot be declared as public. Since external is a subset of public why can't we declare ...
0
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0answers
18 views

Passing a hash value to function

I'm trying to authenticate users by comparing the hashes created by backend server and contract. Seems like "byte32" values cannot be coerced into strings. So, instead I'm converting it into ...
0
votes
0answers
19 views

Best practices with ERC20 forwarding and kill switches

Background I have a system with 2 smart contracts; EventSender and Forwarder ("E" and "F" respectively). E takes a construction parameter of type address payable and sets that to ...
1
vote
1answer
13 views

Modifying erc-721 transfer

Say I want to take a cut of an NFT each time the token is transferred. If I were to change the openzeppelin erc721 transfer function to transfer 1% of the NFTs holding to myself, can that standard ...
0
votes
0answers
17 views

Requesting ropsten ETH / Not receiving rinkeby ETH

Ropsten address "0x28c2fdd94dda609ed825d5f5648568942fdb2e13" Rinkeby address "0xf5aa7ee414226b7dea69018b83e0bd162830ca85" If anyone can send me some test ETH I would greatly ...
2
votes
1answer
26 views

“out of gas” message when calling another solidity contract's method

I want to call another solidity contract's method using Call/DelegateCall. Although the transaction seems successful, but I did not get the expected result, and it shows "Although one or more ...
0
votes
0answers
22 views

ReferenceError: window is not defined [closed]

I found this solution to work around with now new way of wallet integration, but getting Window not defined error..... I am using Node/Next/React Js from a tutorial and trynna modify it since his ...
0
votes
0answers
6 views

Etherscan yul optimizer verification

Is it possible to verify contracts on etherscan.io using the yul optimizer? Example truffle-config.js relevant section: compilers: { solc: { version: "0.5.16", settings: { ...
0
votes
0answers
6 views

Gas Limit not accurate from Genesis

Gas Limit is not matching the genesis blocks determination, the "gasLimit": "0x895440" is getting me this "Error: Returned error: Transaction cost exceeds current gas limit. ...
0
votes
0answers
20 views

How to perform Web3 & MetaMask user sign in

I'm new to blockchain development and would like to build an app with node.js, express.js, next.js, web3, meta mask for user sign in. Are there any good docs that would help me out thank you.
0
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0answers
18 views

Is it safe to store mnemonic seed in the email if I change random 2 words? [closed]

If I store 12 word seed in the email like gmail and my phone as well but change 3rd and 7th words in the seed for example with other bip-39 words and remember it, would that be safe? I can't think of ...
0
votes
2answers
27 views

solidity, how to wait n second function or others solution

I am working on a project for p2p energy trading using blockchain. I am building an experiment on my own to demonstrate the concept for my master thesis. For this project I have two python scripts, ...
0
votes
0answers
8 views

How to show exchange tab on etherscan [closed]

My token is registered on Bittrex, now I want to show current price in ethers on https://etherscan.io/token/0x... under overview. How can I link Bittrex price with ehterscan?
0
votes
2answers
18 views

Copying Private chain data to another private chain

I have two independent private chains running with unique genesis file each. If we use same accounts in both the chains is there a way to copy the state or data of chain 1 to chain 2. Regards, Manoj
0
votes
0answers
16 views

`web3.eth.abi.decodeParameters()` not returning correct values

I call to a method that returns two contract addresses, like this, where method is the method object taken from the ABI (triple-checked that already): web3.eth.call( { from: account, ...

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