Questions tagged [tokens]

A token is a transferable, divisible object on the blockchain, such as a subcurrency or a prediction market share.

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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 ...
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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 ...
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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 ...
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How do I get a list of tokens held by an Etehereum address?

TL;DR: wanted: a method that receives an address as a parameter and returns an array of token names/contracts/balances held by address. I'm aware of the fact that Etherscan API has a method allowing ...
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How do I get the available reserve size for a given token on Kyber and Uniswap(V2)

I am doing arbitration with some measure of success; but I suspect I am running into edge cases where the available reserve size is less than what I am trying to buy or sell. Something like this: ...
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How to write contract on Etherscan

I've $15 in one wallet and $2 in another. I've used smart contract to transfer the funds. Now, the problem is that - on Etherscan, there's "Write Contract" method and under that - cast ...
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Proxy calls are all reverting in test suite despite implementation being set and initialised

I am currently writing an upgradable contract using the unstructured data proxy model and an ERC20 token implementation (similar to USDC). This means the traditional approach of sending a transaction ...
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This declaration shadows an existing declaration(problem with compile) [closed]

function isOwner(address _owner) public view returns (bool isOwner) { return owners[_owner]; } function isOwnerChoice(address _owner, address _newOwner) public view returns (bool ...
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how to connect ethereum local provider https://localhost:8545? [closed]

I am using infura web3 provider in ethereum but I don't want to use third party providers in my project so I want to use localhost:8545? how to use this provider? Is it connect to the ethereum node? ...
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How are rewards commonly distributed to token holders without requiring too much gas?

There are various platforms and tokens which distributes some sort of reward either via staking or interest to token holders proportionally to their token holdings on a regular basis, what are general ...
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Where can I find full ERC 721 example programs?

I am building a program with an ERC 721 token. My code runs without using the standard components provided by Open Zeppelin IERC721. Now I want to adapt it to the ERC 721 standard. Unfortunately the ...
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How to build an Ethereum hot wallet for an exchange

I’m developing an exchange. When a new user register on website we will create new eth wallet for them. When they deposit USDT on their wallet how can I transfer that USDT amount to another address (...
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Why do people even play CryptoKitties? [closed]

I've been lately trying to understand tokens in Ethereum, which basically makes me ponder ERC20 token standard... I still am very much confused in all of its concepts, but the main thing that I haven'...
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Extend old contract or deploy new after fixing, recommendation?

Unfortunately, we used different transfer function name in our smart contract which causes issues for us to list it on some exchange, transfer function name should be transfer but we used ...
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Transfer from MyEtherWallet not working

Transfer tokens from our contract to other addresses not working on myetherwallet, below is the screenshot of from where when we transfer it will deduct the gas and transaction was successful. ...
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send custom token not working from myetherwallet

I added one custom token to mywallet and want to transfer it to another wallet. I used "Send" method from web interface, transaction succeeded but token doesn't transfer. https://etherscan.io/tx/...
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Right approach for syncing balance between ethereum contract and local database balance

So we are using an ethereum smart contract to store investor balances and also storing their balances in local portfolio tables. What would be the right approach to sync in a balance between ethereum ...
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Implementation Question for Licence Token

I am currently working on the idea of using token as licences for digital products. I am offering different documents and books in pdf format and want people to be able to buy them with ETH o.ä.. I ...
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Writing a function, where users are allowed to deposit their token

i want to create a smart-contract, where it is allowed for users to deposit their ether/tokens in. As far i researched i found this function to get it happen. address owner; // this is where you ...
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Ethereum token not logging txs

I'm back again with another token question. If you have seen my previous posts, they have all been about merged mining and prevented eth burn, etc etc. I am in the process of creating V2 of a token I ...
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How can I replicate the Token Tracker etherscan page using python and etherscan API?

So I want to list top tokens and their associated stats, like on https://etherscan.io/tokens. Even simpler than that, how can I use the etherscan python API (or https://github.com/corpetty/py-...
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Maximum totalSupply of an ERC-20 token? And is it different for any other ERC specifictiond?

uint256 This storage implies that it should give us a max totalSupply of 2^256 - 1. A HUGE number. Note: I only need to store integers, not fractional values for my application. Is this true? Is ...
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Sending transaction from different addresses in truffle test case

I am having an admin in my contract who can do certain things. Here is the contract function changeAdmin(address admin_) public { if (msg.sender != admin) revert(); potentialAdmin = admin_; }...
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How to infer token price from ethereum blockchain UniSwap data?

I would like (if possible) to infer a token price from the blockchain using UniSwap data. After reading the following article, I understood that it is feasible: https://blocklytics.org/blog/uniswap-...
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Like an ERC20 interface, do we have any interface or a smart contract that supports creating and transferring Ether on Ethereum?

To create a token on Ethereum, we use ERC20 token interface to design our token smart contract that captures functions required like mint(), tranfer(), balanceOf(), etc. Similarly, do we have any ...
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Does crypto coins are transferred same as tokens?

If I understood correctly, when I want send a token using wallet (e.g., ERC20 token), I will: create a transaction (using send button on my wallet interface) with "to" address containing token ...
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Usecase for approve and allowance functions of ERC20 token

Could you please enlighten me on how approve and allowance functions work using a usecase? I dont understand the underlying operations of these functions. Especially, when a token owner delegates the ...
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Wallet transactions call functions in (ERC20) token contract to send tokens?

Firstly, thank you for helping me out in understand this. Suppose, if I have an ERC20 token contract (with all the required functions implemented including Transfer() function) deployed on the ...
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Buy tokens form other smart contract using interface

I have two separate contracts, let's say Token and BuyFrom. pragma solidity >=0.4.22 <0.7.0; interface InterfaceToken { function invest(address contributor) external payable; } contract ...
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Why token value is getting changed on Ethereum?

I have created ERC20 token with 18 decimals. From web3 (application front end) when I transfer 100 tokens, on etherscan it shows 0.0000000000000001 . When I call to get the balance then on UI it ...
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I have an ERC-20 token created. How does it get value now? [duplicate]

Ok, so a friend of mine helped me create an Ethereum token for me with a 1M supply. I call it the POTTA token. I have also started distributing my token to other friends with a tool that he built so I ...
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Why can only operators transfer between partitions (ERC1400)?

I came across this line in the ERC1400 implementation (by polymath I believe). if (operatorData.length != 0 && data.length >= 64) { toPartition = _getDestinationPartition(fromPartition,...
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ERC20 token not showing up in search

I just created a new ERC20 token on the ropsten testnet. The contract is verified and can be seend here. However when I try to search for AtariToken or ATAR I don't get any results on ropsten....
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How to config geth node to get ERC-20 tokens balances

I'm trying to tune my geth node to get ERC-20 tokens balances, but y API call always returns {'jsonrpc': '2.0', 'id': 1, 'result': '0x'} My geth node version: instance=Geth/v1.9.13-stable-cbc4ac26/...
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How to set token price inside the contract for ICO?

I am confused with decimal places and how it effects the rate of token we set for ICO etc. Lets say, ERC20 Token A have 2 decimal places and per ether 10 tokens shall be sell, then how shall I set ...
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Compiler version incompatibility nightmare

I'm new to Solidity and Truffle. I'm trying to compile my Solidity code within Truffle to create an ERC-20 token. I have @truffle/hdwallet-provider and @openzeppelin/contracts as my dependencies. Now,...
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“VM Exception while processing transaction: revert” in Truffle test and Truffle dev

this is my problem :) Issue "Error: Returned error: VM Exception while processing transaction: revert" when reaching the Transfer function. I think it is related to the fact that my Crowdsale smart ...
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Receiving error while getting state variable value after using selfdestruct method “Error: Returned values aren't valid, did it run Out of Gas?”

I am using selfdestruct method and passing the payable address to it but receiving the following error when trying to get the value of a state variable : "Error: Returned values aren't valid, did it ...
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Can't people be tricked into calling approve on an ERC token contract, and having their tokens stolen?

Most users of Ethereum and ERC tokens probably aren't aware of the existence of the approve and transferFrom functions. Couldn't users unknowingly call approve on an ERC token contract, and ...
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When and where do I set ERC721 tokens' data?

I am currently working on a smart contract to sell ERC721 tokens. I understand that my code should have a function that allows me (the owner) to mint a token and add it to a list which stores all the ...
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How to create ERC20 token with burns 0.5% of tokens on transfer?

I want to create an ERC20 token. It must burn 0.5% of the tokens at every transfer. For example, When someone send 100 tokens from wallet1 to wallet2, wallet 2 must take 99.5 tokens.
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Unable to verify if a contract's tokens is greater than the requested amount by ther buyer

I want to explain you the problem so that you don't need to read the whole files. BirTokenSale contract is trying use the tokens given to it by another contract ,BirToken contract, and send the money ...
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Creating unreasonably large amounts of money as a result of integer underflow in smart contracts?

So, according to this article: https://blockgeeks.com/guides/underflow-attacks-smart-contracts/ "Imagine a situation where a token holder has only X tokens. Suppose he tries to spend X+1 tokens. ...
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Noobish question about USDT and ETH

I want to have some USDT and send that to my metamask account. If I have only USDT on my empty metamask account can I sed that USDT to another person without having ETH for the gas price? Cause other ...
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What's the correct address of SNX?

That is, the address of the token used as collateral in the Synthetix ecosystem. I found two addresses: 0xC011A72400E58ecD99Ee497CF89E3775d4bd732F 0xC011a73ee8576Fb46F5E1c5751cA3B9Fe0af2a6F The ...
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Can you open an Ethereum wallet containing Bank to the Future Tokens if you have lost the mnemonic key? [duplicate]

Looking for help to locate and open wallet.. Many thanks, Nick
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Create multiple ERC-20 tokens without deploy a contract everytime?

I would like to write a smart contract that can issue an erc20 token when asked (with some required parameter, as name, symbol, decimals, and owner address). From what I understood I have to deploy a ...
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Sending Token from A to B and in return receiving data from B to A in same transaction?

Is it possible to send a cryptocurrency as a payment and in return getting data about a product that is shipped to you in one Ethereum Transaction like you can see in the attached picture? If yes, how?...
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Estimating gas of an ERC20 transfer

I'd like to estimate the gas of a simple ERC20 transfer between two addresses. The web3.js docs on estimateGas are admittedly confusing: // using the callback myContract.methods.myMethod(123)....
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Use custom ERC20 addresses

I am pretty new to the Ethereum and ERC20. I am willing to create an ERC20 token. I see that ERC 20 tokens can be transacted using the Ethereum addresses. However, I am wondering if it is possible to ...

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