All Questions

Filter by
Sorted by
Tagged with
0
votes
0answers
5 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 ...
-1
votes
0answers
7 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/...
0
votes
0answers
17 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
0answers
14 views

what replaces assigning array.length to 0 for clearing it

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
votes
0answers
12 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 ...
0
votes
0answers
12 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
0answers
13 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
4 views

Connecting get 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
6 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
8 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
12 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
votes
0answers
17 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
15 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
20 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
20 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
5 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
15 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
votes
0answers
15 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
23 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
14 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
12 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, ...
0
votes
0answers
12 views

What token address do I use if I want to sell an ERC20 token on a different exchange? Its original address or its address on the other exchange

I really need help with this one to avoid logic errors. I am on the Kovan testnet. I bought 4 units of DAI token on Uniswap exchange(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D) for 0.111 Ether and ...
1
vote
1answer
13 views

How to cancel a pending transaction from command line?

I have a private key. I need to cancel a pending transaction sent from its address. How to do this from command line? Also: I need to do the exactly same thing if there are several such pending ...
0
votes
0answers
18 views

Can someone read this private variable?

my purpose is to generate a random key when the smart contract is created and save that key in a private variable. I don't what to know its value either. Let's take for example the code below: pragma ...
0
votes
0answers
10 views

how i send data from different account using web3.py to smart contract

The project is a group of Ethereum users, who wants to send their data to the blockchain network to be saved, this data is sent by these users by Python. My question, how is this data sent by users, ...
0
votes
0answers
21 views

How to mine without entire computer slowing down?

My computer is a dream machine with 64gb RAM and 28 cores operating at 4-5Ghz. Using Linux Mint. I also have a fairly modern Nvidia graphiques karrd with 8gb VRAM. I am mining XMR on 24 of my 28 cores,...
0
votes
1answer
9 views

array.push replacing last value instead of adding to the array

I am attempting to keep a log of when a user does certain things but when a new log event is reached the second log is overwritten instead of adding a new one to the array I am unsure as to why when ...
0
votes
0answers
8 views

Does Ganache Support Mappings?

I have a function where I am trying to compare the values of 2 mappings. However, I am receiving an invalid opcode error. Which has me confuzzled because I already set the values of both the mappings ...
0
votes
1answer
19 views

How can I calculate percentage of a number in solidity? [duplicate]

How can I calculate percentage of a number in solidity? say I want to calculate 95% of the number 200. How should I go about doing that ?
1
vote
0answers
15 views

debug_traceTransaction says tx failed, etherscan says passed

I was running debug_traceTransaction on the transactions in the first 100,000 blocks, and I came across 25 that were flagged as failed, but etherscan.io says they are fine. The gas used is below gas, ...
-1
votes
0answers
17 views

Python UserWarning [closed]

when I use stanfordnlp for Arabic language I keep having this errors ..\aten\src\ATen\native\BinaryOps.cpp:81: UserWarning: Integer division of tensors using div or / is deprecated, and in a future ...
0
votes
0answers
15 views

Insert data whithout overwriting the already stored whit the same address

i'm new to solidity and i'm developing an easy app. This is the contract i'm working on. It's all functioning but i need to: do some sort of function that return me all the array value whit the same ...
1
vote
0answers
14 views

Does the term “Ethereum ECDSA signature” have a consistent meaning?

If you were writing some instructions and one of them was: Provide the Ethereum ECDSA signature of the file using the person's Ethereum address. Would the above instruction have a consistent meaning ...
0
votes
0answers
14 views

GETH full node genesis mismatch

I was running a full node GETH client for main net Ethereum in a server. The server crashed and was shut for around 8 hours. But after fixing the server and running the full node the GETH doesnt run. ...
0
votes
0answers
24 views

debug_traceTransaction returns massive json of opcodes

I ran debug_traceTransaction on tx "0x7faf48b09018e507c49c1c44b139fa05c262fb1e3425a43ae80e6c9ccb3fcf0e" (block 1805546, txindex 1: contract creation), and I received back a massive 157MB ...
0
votes
1answer
12 views

How can the contract move funds from a user wallet to a contract address

We are creating a system where every month some ethers shall be transferred from user wallet to a contract wallet. We are focusing on creating a dapp too, so a user will initiate this request and once ...
0
votes
1answer
22 views

Can ERC-20 based stablecoins be confiscated or be subject to legal process?

Can ERC-20 based stablecoins be confiscated or blacklisted? Can I lose my stablecoins? What are differences between stablecoins out there?
0
votes
0answers
10 views

Parity Max Gas Limit dropping

When running my chain my gas limit drops drastically from the set limit of the genesis block "gasLimit": "0x3B9AC9FF" due to large gaps both in time and frequency between the ...
0
votes
0answers
18 views

file to byte array problem [closed]

Converting a file to a byte array to be stored as bytes[] in solidity I am able to convert the file using the following function, but when I send it to my smart contract I get error "TypeError: ...
3
votes
1answer
18 views

How is Chainlink decentralized? [closed]

I believe one of the main criticisms of chainlink is that it is not decentralized enough, adding more nodes would be a big step in a positive direction. When I pull data through a node, that node ...
0
votes
0answers
34 views

If I have several wallets with the same address, how to deal with nonces?

I access Ethereum from several wallets. Some of the addresses are present in several wallets at once. I discovered that nonces should always increase. (Right?) Then if I send transactions from several ...
0
votes
0answers
8 views

Peers attempting to connect to ports on my machine other than those used by geth

I have a geth node running on a linux machine, and have set up a firewall (UFW) to allow all outgoing connections, but inbound connections to 30303/udp and 30303/tcp only. I'm noticing in my system ...
0
votes
1answer
17 views

Error: Returned error: VM Exception while processing transaction: revert when using methods.MyMethods.Send

I am writing a simple betting application that will return double the ether deposited by the player, provided they guess correctly the random number generated by the virtual slot machine. it works ...
0
votes
0answers
10 views

Error: No Keyring found for the requested account

I am an student and in this moment practicing how to create a simple smart contract in remix.ethereum.org. I got compiled the small program with function get without problem. When I deploy the program ...
1
vote
1answer
32 views

Smart Contract Application in ASP>NET [closed]

I just have started to learn Smart Contract. I have to design front end in ASP.NET. Can I call Contract from it?

15 30 50 per page
1
2 3 4 5
589