Questions tagged [blockchain]

The Ethereum blockchain is a distributed database based on the Ethereum whitepaper specification and stores both the full transaction list and the most recent state.

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Can we mint 5 gigabyte video NFTs?

What is the maximum size of NFTs on the Ethereum blockchain (ERC-721 or ERC-1155 tokens)? crypto art NFTs on the Ethereum blockchain already contain JPG/PNG files that are about 5 MB large, and ...
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Smart contract that will add users to a blockchain and another smart contract that'll verify if the user already exists

I would like to make a smart contract that will add new users to a blockchain, then another smart contract that will verify if the user already exists on the blockchain, I'll be taking the name and id ...
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52 views

How to convert ERC crypto art NFTs into a Cardano NFT?

This is being asked two days before native tokens and multi-asset support hits the Cardano blockchain, but, given that Cardano has created an ERC-20 token converter that converts ERC-20 tokens to ...
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29 views

Can I use conversation messages stored on Blockchain

I'm new to Blockchain and exploring if I can safely store textual and media content in the transaction. This will help me with the following outcomes I can have a safe, secure storage of contents ...
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Is there any way to conduct multilateral netting on a DLT platform?

Multilateral Netting is generally used as a method to counter high liquidity requirement for the participating members. We always use a central clearing house/central counterparty who does this ...
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Learning go-ethereum For Custom Chain

Is there a site to find out all about source code go-ethereum? I want to learn fully about the Ethereum blockchain.I want to learn private blockchain to learn more.
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how to interact with Back-end of a dapp?

I am trying to build a dapp but I am having problems. My idea is: I have a front-end written in html / css and a backend implemented with web3.js thanks to which it is possible to connect to a ...
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1answer
28 views

transactions are performed sequentially by the blockchain, but how are the waiting times managed?

I have a booking dapp where you can make reservations and call the bookRequest method. If many users call this method, it is not possible to know the order in which they will be performed and ...
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how to create a smart contract that uses ERC20 as way of payment?

im creating a smart contract that will receive and automatically redistribute erc20 tokens! how can i implement that in solidity? i've tried a couple of codes examples but nothing have worked so far! ...
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how to call a function of a smart contract from a c program using JSON-RPC

Indeed, i installed ganache where i deployed a smart contract. I wanted to write a c program that would allow me to call the functions of my smart contract and read the messages. This program would ...
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How does a node execute the smart contract in the EVM and update the blockchain with result of contract execution

I would like to understand how the Ethereum Node is loading the contract bytecode in the EVM and then write everything that it needs, back to the blockchain. This is how I understand it. The contract ...
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Please help me understand why this transaction has failed and what has happened to its amount? [closed]

A friend of mine recently had an Ethereum (no token or contracts, etc) withdrawal from an exchange (Phemex). It never arrived, and the status is Failed (Out of Gas)! Here is the TX: https://etherscan....
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How to reduce time for block confirmation in the Ethereum blockchain and also time to listen to logs emitted?

I am designing an application in which I am emitting logs through transactions in the Ethereum blockchain. I also created an event listener to listen to the new logs emitted. But I want time from ...
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Pending Transactions [closed]

I am reaching out to the Ethereum community hoping to get better understanding of what my fiancé created with his platform. When we log into BTC.com (Blockchain explorer) and Etherscan.com we see ...
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How to use promises with drizzle/vue-plugin

I'm trying to implement a blockchain based app. I'm using Drizzle Vue plugin to interact with the methods in smart contracts. However, I stumbled across the following issue. After executing the ...
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API for circulating supply

I am trying to list circulating supply on coingecko for an ERC20 token - how would I go about doing this? I've been able to find one for total supply, but not circulating however.
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Please help with Parsing Expected ',' but got ';'

I have looked far and wide for a solution and have read solidity documentation. Please help me find the parsing error in the code. Thanks in advance. var KiwiCoinSale = artifacts.require('KiwiCoinSale'...
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Parse the whole blockchain

I want to parse the whole blockchain(I know it might sound a bit too much). I have installed both solidity and geth. My idea was to get the current block that is being mined, essentially the current ...
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Using Phoenix Miner - Noob Question

I am using Phoenix Miner - Ran it for around 8 to 10 hours as a trial - I setup my Public Wallet ID as My wallet ID, I have yet to see anything pending into my account - I am wondering If I am missing ...
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Invalid implicit conversion from rational_const 5 / 2 to uint256 requested

I have the following code snippet inside my contract: plans[1100] = Plan(7, 3); plans[1101] = Plan(7, 2.5); plans[1102] = Plan(15, 4); plans[1103] = Plan(30, 6); plans[1104] = Plan(30, 5); When I try ...
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Find ETH address with amount range (Query Big Data)

I'm trying to run a query similar to this: https://medium.com/google-cloud/how-to-query-balances-for-all-ethereum-addresses-in-bigquery-fb594e4034a7 But I would like to find ETH address: Ending with ....
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1answer
22 views

how to accept and pay in Erc20 on my smart contract? [closed]

im creating a smart contract that i would like to receive and automatically redistribute erc20 tokens! how can i implement that? i've tried a couple of codes examples but nothing have worked so far! ...
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1answer
34 views

Is Ethereum a decentralized or distributed blockchain?

Is Ethereum a decentralized or distributed blockchain? I read the documentation but I can't understand.
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Problem with old Xeth wallet syncing up

I've got some ETH on an old XETH wallet from 5 years or so and I've never been able to retrieve it. The ETH doesn't show up in the wallet and the sync bar is completely blank. Based on another ...
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1answer
24 views

How to write a smart contract for access level (read/write)?

I have seen a couple of tutorials on how to code smart contracts, but I can not quite gather how to write one for permission and access level on a blockchain. How can you grant access to a user to ...
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what are the technological limits of a smart contract?

I know that: a smart contract cannot initiate any type of transaction but needs an external trigger. Each transaction is triggered by an EOA Smart contracts cannot subscribe to events or access them ...
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Get balance in fast node by Geth

Is it possible to get account Balance in fast node with Geth ? and what is the size of fast node currently?
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Can my backend call a smart contract function to be executed on a certain date?

The architecture of my dapp consists of a backend (metamask + web3.js or web3.js + geth) and a smart contract that offers different services (functions). I want a function on the smart contract to run ...
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55 views

why aave total supply not equal to circulation supply?

I'm new to the blockchain world. I'm trying hard to understand how tokens are generated and I learned that the tokens are not minable, unlike bitcoin or eth coins. also learned that these tokens only ...
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2answers
32 views

why does it matter to sync nodes with time?

As we know, time gets set on a block's header as the miner's current local time. Each node while accepting a block, checks if the new block's time is more than parent 's time and is not also in the ...
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1answer
19 views

How to call a function with ethereum alarm clock?

In Ethereum alarm clock who is calling the contract (scheduler?) that executes the function programmed in my contract. I mean, I have a function in my contract that needs to run on a certain date, but ...
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1answer
15 views

How to build local ETH2.0 test net?

I'd like to build ETH2.0 blockchain on my computer. And I want to know how to become a validator using that. I read many documents but I can't get this way. (I think that Geth is for ETH1.0. Is this ...
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25 views

scheduling of smart contract functions

I am reading the alarm clock documentation http://docs.ethereum-alarm-clock.com/en/latest/ but there are things I don't understand. I have a dapp where the smart contract has different functions. For ...
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55 views

difference between metamask and ethereum provider

I found this image online but I can't tell the difference between metamask and an Ethereum provider. Also doesn't metamask use a provider to connect to the network? I'm confused
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Non ERC 20 coin sent by mistake to MyEtherWallet (MEW)

Newbie here - apologies for anything inappropriate and lack of tech expertise. I made a dumb mistake and sent some THETA tokens to a MEW Ether address. My bad - I had not realised that THETA had moved ...
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1answer
35 views

If I don't use metamask who manages the private key and the incoming or outgoing ether?

I want to build a dapp without using metamask but web3.js and a node (geth / parity). So if I use this second method what happens when ethere needs to be sent to an account?
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1answer
42 views

Attempting to transfer erc20 elrond to elrond gold in trust wallet - error insufficient funds

Does anyone have a step by step guide to transfer my 7566 elrond to elrond gold? My elrond is in Trust Wallet and tried to send to my elrond gold wallet but network said I have insufficient funds and ...
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1answer
134 views

How can I download the entire Ethereum blockchain?

Is there a way to "get" the whole ethereum blockchain in order to process it locally? For example a link for direct download or via a developer API? Thanks in advance!
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31 views

Is it possible to schedule a transaction to execute after a certain amount of time in ethereum? [duplicate]

Is it possible to schedule a transaction to execute after a certain amount of time in ethereum? For example, I have a dapp where after two weeks I want to call a getRefund function on the smart ...
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55 views

Error: VM Exception while processing transaction: revert UniswapV2: LOCKED

I am using this repo to begin testing UniSwap flash swap contracts. I've installed all dependencies correctly and cleanly. The project uses ganache-cli, hardhat buidler, and yarn in the terminal and I ...
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1answer
29 views

how to interact with an already deployed smart contract

I was reading this contract https://docs.soliditylang.org/en/develop/solidity-by-example.html#safe-remote-purchase that I found in the solidity documentation and I assume this contract is unique and ...
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interact with a contract deployed by another account

How do I send transactions, subscribe to events and call methods from a contract already deployed on the blockchain? (in web3.js)
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Is it possible to access an already deployed smart contract without using metamask?

Suppose a user wants to access a contract on the blockchain hat was distributed by a company. Can it do this without the use of metamask? If so, how?
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replace metamask with web3.js

Is it possible to replace metamask with a web3.js + geth / parity solution in a dapp? Or do you need the infura service? What is the difference between using metamask and web3.js + node? Are there any ...
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17 views

Is the interaction with the smart contract safe?

I am working with ethereum and I have a doubt. In a real case, can a user interact directly with a smart contract? Are there no dangers? For example: a user wants to book a trip. What happens in these ...
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Should I run POW or POS for local Transactions?

Since prof of Stake is here, and proof of work is in decline, I am trying to figure the best corse of action. I need a local node, Geth node, and I need to be able to post transactions and retrieve ...
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30 views

how to set a require for a string to not be null

I want to write a require condition for string that string variable could not be null. How to write because string is not taking the != operator function createOrder(address _seller, string memory ...
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1answer
29 views

How to send ether from sender account to a given account

I am new to solidity and trying to develop a small smart contract. I want to send ether from the sender account to a given account. But I always get this error "VM error: revert. revert The ...
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49 views

How do EOAs work and what is their interaction with smart contracts?

After reading and searching online, I still have many doubts about how EOAs work and their relationship with smart contracts. The idea behind my dapp is to allow users to make reservations. It also ...
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13 views

intercation with smart contract

I am working on a dapp based on hotel bookings. I have a refund function in my smart contract. The smart contract can receive transactions from a single EOA of a component (contract manager) in the ...

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