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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Guidance on creating new token with value tied to fiat currency & fixed increases in price (newbie)

I would like to create a new token, but I'm a complete newbie when it comes to Ethereum and cryptocurrencies/blockchain in general. I'm also not a programmer. My goal is to create a fixed number of ...
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Best way to create identity contracts for organisations

What is the best way to create identity contracts for organisations based on their information like name, address, organisation type(buyer/seller) etc. I have tried using factory pattern to create ...
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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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Send multiple transactions

This is contract I plan to implement multi send, so I can send multiple transactions to people. Here is my code pragma solidity ^0.4.11; /** * @title Ownable * @dev The Ownable contract has an ...
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Assertion error running truffle test

I can't seem to understand where this error comes from. Maybe someone can help My token solidity file : pragma solidity >=0.4.2 <0.6.0; contract LairToken { //Name string public ...
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Tokenizing Art (Image Hash & Rarity) [closed]

How do I create a token with two fields, specifically for art? image hash (sha512sum) rarity (1of10) Whats the current standard for tokenized art? How is the rarity guaranteed? Are there any ...
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1answer
190 views

Custom token transfer, what am I doing wrong?

I am trying to hash an address then send tokens to a mapping of the hash in the token contract, then be able to withdraw those tokens using a hash of the address. It compiles but cannot make it work. ...
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1answer
175 views

How can I collect the tokens inside smart contract that people will send accidentally?

I have an ERC20 token XYZ smart contract created. People will send certain amount of tokens back to the contract address to initiate certain functions. I just want to know that what will happen if ...
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What are contract Variables and how are they different from normal varables declaration

pragma solidity ^0.4.2; import DappToken; contract DappTokenSale { address admin; DappToken public tokenContract; function DappTokeSale(DappToken _tokenContract) public { ...
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1answer
118 views

How to send ERC20 token from smart contract in Solidity?

I want to make a smart contract, where you can instantly swap your Ether to ERC20 token. What I do have now: pragma solidity >=0.4.16 <0.7.0; contract Swap { address owner; address ...
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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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1answer
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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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COB token transfer failed with error: “Bad Instruction”; will I get my tokens back?

I transferred 10 COB tokens from my one address 0x782e265f911167e4FDbfbFb63a32cC27341724E7 on my Metamask wallet to another Metamask wallet address 0x0a42AD94FC81db989575365Be28DCd64417Ce564 but the ...
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356 views

How are tokens related to dapps?

I have seen almost all the DApps have some kind of tokens, ICO associated with it. Anyone kind enough to explain what is the relationship between a DApp and Tokens?
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1answer
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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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1answer
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Zepellin Crowsale buyTokens error

I'm trying to use the buyTokens function of the Zepellin Crowsale interface, but this gives me an error, without any log to be able to debug contract TokenA is MintableToken, PausableToken, ...
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1answer
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What data should be stored in contracts or tokens

After watching a sales force movie where they have a session on how they are integrating their product into the blockchain they talk of an example on capturing all the data from the supply chain ...
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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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How to set rate in decimals in solidity?

I want to set my price of token sale in ICO as 1 ether=0.0111111111. Since, solidity doesn't support decimals, what is suggested way to do that?
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1answer
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transferFrom error. Exception thrown in smart contract transaction

I compiled smart contract in solidity on remix.ethereum.org. I made account via MetaMask and want to let other addresses send tokens to themselves using ropsten network. I mean - I am contract owner = ...
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2answers
360 views

ValueError: {'code': -32000, 'message': 'invalid sender'} when calling transferFrom using web3.py

I want to make a function that allows you to send tokens from one owner to another. nonce = w3.eth.getTransactionCount(from_['address']) unsigned_transaction = contract.functions....
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67 views

Ethereum Contract Scalability (Single vs Multiple Contracts)

I am writing a token swap contract on Ethereum Blockchain to manage ERC 20 token swap in an exchange. The Questions is that in terms of scalability, which of the following two options would be better ...
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Smart contract with authorized actions based on addresses

I want to build a service where users can sign up (off-chain) to get credentials which give them the right to perform certain on-chain actions. For example, lets pretend I'm building a service where ...
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1answer
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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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1answer
247 views

Invalid type for argument in function call

I have this token code pragma solidity ^0.4.19; contract MyToken { mapping (address => uint256) public balanceOf; function MyToken(uint256 _supply) public { balanceOf[msg.sender] = ...
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1answer
210 views

ERC token multiple address sending

Hi is it possible to send token XYZQ to two addresses in one transaction. here is example. 100 XYZQ ===> 99.9999 to XYZQ 1 address and 0.0001 XYZQ to second XYZQ address? For same amount of gas
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1answer
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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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1answer
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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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536 views

function () public payable modifier can trigger actions when sending tokens or only works when sending ether?

Modifier payable triggers an action when an address sends ether to a contract. For example: function () public payable { require(msg.data.length == 0); DoSomething(); } Is this ...
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1answer
543 views

How to add website link to erc20 token on etherscan.io

How can we add this official site link to our deployed contract? Like in the image below: Here is my deployed contract address: https://etherscan.io/address/0xab73a739729a21b2299761408507556d2719af89#...
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1answer
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Ethereum crowdsale example - Stuck tokens (how to save)

I deployed a crowdsale contract using the source from ethereum.org and loaded it with some tokens. It works as expected, except that it has no code to return the unsold tokens to the beneficiary. Is ...
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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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1answer
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gas estimate in loop

I have two contract. I call function placeBid in other contract and i have warning gas estimation. help me. thanks. Can i call function which use gas in loop through other contract? How i can get ...
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1answer
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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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267 views

How can users call the functions of an ERC20 token that was created by another contract (within a crowdsale contract)?

Using Ethereum wallet if I create a token and deploy it I can then interact with it and use the functions of that token (e.g. transfering tokens). However, if I deploy a crowdsale contract and that ...
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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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3answers
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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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1answer
286 views

How to download the whole transfer records of a token

I want download the whole transfer records of a token. https://etherscan.io/token/0xB8c77482e45F1F44dE1745F52C74426C631bDD52?a=0xd551234ae421e3bcba99a0da6d736074f22192ff. But the default setting is ...
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1answer
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For loop for transferFrom

transferFrom method from ERC20 contract interface: function transferFrom(address _from, address _to, uint _value) public; transferFrom function from my contract : function transferFrom(address ...
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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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3answers
318 views

Transfer ERC20 Token feeless

Is there an existing Smart Contract implementation, which can public signed transactions of ERC20 Token transfers? I like to give the users of a ERC20 token the ability to pay the transaction fees in ...
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1answer
21 views

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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Accessing funds that are sent to the smart contract address

If someone creates a smart contract (and is owner of that contract), is it possible for that person to collect ETH and other tokens, that are sent to the address of smart contract?
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How can I make my contract send out my tokens?

I've been experimenting with some generic copy-paste codes on the Ropsten Test Net and I am able to create a token and have the creator receive all the tokens. However, when I try to buy these test ...
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2answers
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Ethereum Solidity Contracts w/ Fiat Money

Is there anyway to fix a price for a ERC20 token? It seems like a major problem with blockchain and crypto is all of the volatility, which is why I am hesitant to use it for applications even though ...
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279 views

Questions Regarding Creating New ERC20 Token & ICO

Hi I want to create an ERC20 token and launch an ICO. I am new to ethereum solidity. I have checked smart contracts on http://ethereum.org and https://theethereum.wiki/w/index.php/...
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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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1answer
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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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531 views

How to peg value to token outside ethereum

I have an online game system. I issue some tokens through ethereum. How can I peg value of the tokens issued on ethereum to my game system, which is outside the ethereum eco system. (ie) The users ...

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