Questions tagged [erc-20]

The ERC20 Token Standard is a set of 8 functions to be included (in an agreed upon language) in a smart token contract in order to enable interoperability across multiple interfaces and dapps. These functions relate to (1) how tokens can be transferred (2) how to access data about the token, and (3) how to format key events like transfers and approvals. ERC stands for Ethereum Request for Comments.

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Returning ERC20 tokens accidentally sent to the DAI contract

I don’t know if it’s the right place for it, but I’m taking a chance. Despite several years of daily use of ERC20 tokens, I unfortunately managed to make a mistake and send some ERC20 tokens to the ...
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A contract inherit from a token contract

I have a token contract(ERC20) A, then another contract B inherited from A (B is A). A contract C imported B. questions are: if I deployed B alone, is the address of this contract B represent the ...
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how to find destination address and value from transaction

How to find destination address and value from transaction detail? Network: rinkeby destination address is: 0x5e6b735c855cf7f44f179c25c98195ace9eb972b token value is: 100 LINK but this items doesn't ...
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Gas payment of the mint of ERC20 Token

I have the follow use case: There is an off-chain service, like a game, which will generate/mint new ERC20 tokens when some requirements are met by end-users. Since the users will get profit (in terms ...
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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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1answer
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What is the best (cheapest) method to store RGB/RGBA pixel data in a smart contract (on ethereum-classic blockchain) with python?

I would to implement a method to store pixel (RGB/RGBA) in a Smart contract (on ethereum-classic blockchain) from python and with the cheapest method ( when storing and updating pixel data) I try to ...
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1answer
229 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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1answer
556 views

Is it possible to send ERC20 tokens to a smart contract that is written to accept payments..?

I have ERC20 compatible token that is already deployed in the ethereum main-net. I have a requirement to accept these tokens as payment, And this is going to be a new contract, The below are my doubts....
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1answer
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Changing end date to smart contract?

Newbie question. Can someone walk me through the steps I have to take to extend the date to my smart contract from May 2, 2018 to August 2, 2018? Like to try without asking my programmers for help....
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How to read the Ethereum Block header and check contract

I have downloaded some Ethereum block headers, such is one example (omitted some details for conciseness): {"difficulty": 7314508281338, "extraData": "...
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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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transfer to particular address on function call

How can I make a function that sends balance of the contract to a particular address? I want it to be hardcoded at the time of contract deployment. Also, how can I trigger a function if the contract ...
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Need a lot of help. Price/listing/etc [closed]

So I have this contract 0x3d7c1Ad6009a2Ca376b97415BACB20B2D2b9bAae But I don’t know what to do now. I don’t know if it’s possible to list it (On uniswap) and give value to each token plus do an ...
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I written an ERC20 token contract, now I have to use my token in another contract for transaction amount. How? [closed]

Taking help of openzepplin, in making ERC20 token , I now have to use this token in multiple contracts for various use. So, how do I code my ERC20 token into other contracts, so that at time of amount ...
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Send all Tokens and Eth to a Address automatically

I have few child wallets and a parent wallet. Whenever these child wallets get incoming ERC20 tokens or ETH. I want to send them automatically to the parent wallet. I know I can do below to send the ...
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API for ERC20 token balance - EtherScan

Is there any API for ERC20 token balance of an address for a particular contract?
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How to send ERC20 token using Web3 API?

I created some custom token in Ropsten testnet using this guide: https://steemit.com/ethereum/@maxnachamkin/how-to-create-your-own-ethereum-token-in-an-hour-erc20-verified I can send it to other ...
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Send erc20 tokens using the json-rpc api

I need to send ERC20 tokens (golem to be precise) in an automated manner, so I set up a geth json-rpc server with ./geth --fast --rpc So I can call the api just fine. The documentation for ...
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Automatic ERC20 Token Payment System - How to

Before starting to detail my problem, I must say that I am new to ERC20 Tokens and I write this question in ask for guidance. Is it possible that I can forge a payment system on an ERC20 token? What ...
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1answer
435 views

How ERC20 Token balance are recovered during Ethereum chain rolling-back

My Answer: Ok, the problem is really with Ganache ... If I use geth, everything is alright. ... ... sorry for your time ... ---------------- The Original Question -------------------- My ...
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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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Subscribing to multiple Transfer events of various ERC20s

I need to suscribe to Transfer events of couple of different ERC20s in order to catch transfers to my contract. And here is the question: to catch all those events I need to create instance of each ...
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_transferFrom vs. _burnFrom order of operations (Zeppelin ERC20burnable.sol)

I have question, more for my understanding than anything. Here’s the transferFrom function in the ERC20 standard: function transferFrom(address sender, address recipient, uint256 amount) public ...
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1answer
561 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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I sent my ERC20 token to a wrong ERC20 token address in FTX . Can I recover those [closed]

I SENT MY MEME TOKEN (ERC20) FROM METAMASK TO USDT WALLET (ERC20) ON FTX. THE USDT ADDRESS (ERC20) ON FTX BELONGS TO MY ACCOUNT. IS THERE A WAY TO REVERT THE TRANSACTION SINCE LUCKILY THE RECIPIENT ...
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1answer
695 views

ERC20 tokens transactions' history from Ethereum node

I have a parity node. I developed a web3.js interface on top of it. I have APIs whose job is to fetch addresses' balances and transactions. Example response of transaction API: { tx_hash: '...
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1answer
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How to create an automatic smart payment ERC20 system

how can I create an automatic smart contract to send tokens ,if a user send ETH to the smart contract and also to bee able to recover ETH from the smart contract and tokens too thank you. To explain ...
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1answer
264 views

Multiple addresses initialization in constructor function

Usually we have one address initialization in constructor function. And that address becomes owner of the contract. While studying erc721 token and going through several examples online i found ceo ...
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1answer
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How to find the value of erc20 token sent out using transaction hash

How can i find the value of erc20 token in a transaction using the hash generated? I can't seem to find answers anywhere. Edit:I found that it is possible to use w.eth.getTransactionReceipt('...
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1answer
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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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1answer
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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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USD Coin Balance Check By Web3

Now I am getting trouble on checking the USDC balance in my wallet address using web3. USDC is also said that it is ERC20 token, but when I checked the token contract ...
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Uniswap Fee or how 180 AMPL tokens suddenly “disappeared” from blockchain

If you look at https://etherscan.io/token/0xd46ba6d942050d489dbd938a2c909a5d5039a161?a=0xfe6c9c5a0d36eba3a767aaf6df2f335e666a74e7, you can notice that there were 3 transactions associated with the ...
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ETH same transaction different amount of gas used

The two transactions: a) https://etherscan.io/tx/0x9227f7b00bf2c98a7e16eb5ab90c04df5b49698297ee7f52c765d5218af395ad b) https://etherscan.io/tx/...
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1answer
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How to add USDT ERC20 Token to private blockchain

I am running a private ethereum blockchain on my machine using geth. I want to send USDT token from one address to another, but I could not because neither address have any USDT token. I have tried ...
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1answer
640 views

Managing ERC20 tokens with a multisignature address

Say I have the following: Address A belongs to me and holds 10 ERC20 tokens, but does not hold any ETH Address B belongs to somebody else and I need to send 10 ERC20 tokens there from address A ...
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If I participate in a ERC20 ICO with my Metamask eth address, can I add the custom token later on?

If I have not added the ICO's token to my Metamask yet as a custom token, can I do it after the token distribution? Like claiming my tokens after it's been sent, by adding the new custom token to my ...
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Remix Compiler Errors - Transferred GitHub .SOL Codes to Remix

I transferred all 23 Sol extension files (smart contracts for Syscoin and Ether) from GitHub to Remix but only 3 of them can be compiled and deployed. The rest of them show errors. [Here is the link ...
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1answer
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Transaction shows up on etherscan and metamask said it was sent, but my token balance is still the same

I made USDC transaction and metamask said it was sent and etherscan also say there was a transaction made as seen below. But my USDC balance is still the same as if it never left my account. And ...
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4answers
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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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What is the cause of an “APPROVED” transaction but doesnt do a “TRANSFER” for an ERC-20 Token?

I have a transaction that was approved and I paid $3 in fees. But the token was never "transfered" where and how can I debug what happen to my transaction of why it didn't transfer?
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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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2answers
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Approve contract to withdraw funds from users's wallet

I want to achieve the following flow: A user clicks a button allowing my contract to spend funds on the user's behalf A user clicks a second button whereupon funds are transferred from the user's ...
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1answer
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can't verify contract on etherscan (But we were unable to locate a matching bytecode (err_code_2))

so i'm trying to verify a contract on rinkeby and ropsten... getting the same error of "Compiler debug log: Error! Unable to generate Contract ByteCode and ABI Found the following ContractName(s) ...
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1answer
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Prevent Transfer of ERC20 token to contract address?

I want my ERC20 contract to be transferred to EOA addresses only and some specific contract address only. I don't want to lose my tokens by mistakenly transferring to a contract address that cannot ...
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1answer
22 views

any decentralize trading platform?

i am thinking about convert eth to btc etc,is there any platform for this? Uniswap can only convert among erc20 tokens but I am thinking about converting among different type of token?
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1answer
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How to add my token to external exchange

I am planning to launch one ICO and before that I am checking how to list my coin in external exchange? If anybody knows please help here What are the mandatory things I have to consider
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How to get contract address with truffle?

The token .sol: // ---------------------------------------------------------------------------- // '0xBitcoin Token' contract // Mineable ERC20 Token using Proof Of Work // // Symbol : 0xBTC // ...
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1answer
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how to use eth_estimateGas for erc20 tokens?

i wanna calculate estimate gas for BNB, PAX, LINK i have used geth 1.8 and web3.php my contract data that used (i found them from etherscan): <?php /** * @var array */ public ...
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1answer
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Open Zeppelin TokenTimeLock - gas required exceeds allowance (10000000) or always failing transaction

I am creating an ERC20 contract using OpenZeppelin, to lock up my ERC20 tokens for a specific period of time. I am trying to deploy this contract onto the Rinkeby test network through remix.ethereum....

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