20
votes
Accepted
What is DSProxy and how does it work?
What
DSProxy is a smart wallet built by DappHub that enables developers to execute multiple contract calls in one transaction. This is something that vanilla EOAs can't do; they are limited to ...
- 18.7k
6
votes
Accepted
I want learn smart contract trading
That’s called arbitrage, you swap e.g. ETH for DAI on one exchange and then swap it back from DAI to ETH on another exchange. This works because the so called DEX’s (Decentralized exchanges like ...
- 410
6
votes
how to deploy a smart contract on same address in ethereum and binance
If your deployment environment employs the CREATE opcode under the hood, The deployed contract address is going to be a function of the deployer's EOA and the nonce.
contractAddress = hash(...
- 4,639
6
votes
Error: chainId address mismatch
i found the answer i have been struggling with this for a week!
i just changed the Network Id in the ganache to 1337! and it got through!!! Awesome!
you can use this code instead to get the chainId ...
5
votes
What are some reliable multisig wallet solutions for Ethereum?
A really good option is Gnosis.
Find more info here:
https://gnosis-safe.io/#getting-started
to create a wallet on Gnosis Safe, go here:
https://gnosis-safe.io/app/#/welcome
- 1,025
5
votes
Help Please hardhat.config.js * Invalid account: #0 for network: Rinkeby - private key too short, expected 32 bytes
Make sure you are copying your PRIVATE KEY and not your PUBLIC KEY.
If you are using metamask, you can get your PRIVATE KEY from
the 3 dots menu beside your public key,
and then account details
...
4
votes
Accepted
How to retrieve multiple values returned from solidity with ether.js?
const result = await contractInstance.yourFunction();
const {0: variable_1, 1: variable_2} = result;
Reference: https://blockheroes.dev/js-read-multiple-returned-values-solidity/
Hope it helps.
- 56
4
votes
Accepted
Detect receiving token address in "receive() payable"
The receive function is triggered by a transfer of the native token only, such as ETH on Ethereum or BNB on Binance Smart Chain.
Therefore, msg.value is always an amount of the native token and never ...
- 3,630
4
votes
Deploying a contract that inherits GnosisSafe from another smart contract
If the goal is to deploy a Safe with custom modules and guards, you don't necessarily need a separate contract to do that. When deploying a Safe, there's a distinct initializer parameter to setup ...
- 1,105
4
votes
Where are the Ethereum smart contracts actually stored?
from the ethereum yellow paper
The world state, is a mapping between addresses and account states (a data structure serialised as RLP).
Though not stored on the blockchain, it is assumed that
the ...
- 1,227
4
votes
Lock and unlock in solidity
Here is what you need:
I modified your code to include logic to unlock 5 percent of the tokens. I added comments as suggestions and clarification.
There are about 2,628,288 seconds on average in a ...
- 4,649
4
votes
why I'm I getting this error: Wrong argument count for function call: 6 arguments given but expected 5.solidity(6160)
In your emit you are trying to emit 6 elements .
But in your event function you are only accepting 5 elements
In emit "amount" is an extra argument
- 123
3
votes
Accepted
Transfer ERC20 tokens of a smart contract
There is two different address in Ethereum.
The one controlled by a private key (usable for a user).
Smart contract that are address controlled by a code (no private key).
If you didn't put a function ...
- 365
3
votes
What is the pupose of TokenID increment in OpenZepplin implementation?
What makes a token unique within an ERC-721 NFT contract is that token’s tokenId. The ERC-721 NFT standard doesn’t tell you how to assign tokenIds to tokens, but only requires that different tokens ...
- 1,418
3
votes
How to get smart contract information about ABI token balance by web3?
You can find if an address is a contract by fetching its bytecode : web3.eth.get_code(address). If it has any, then it's a smart contract, otherwise it's EOA. (Web3py ref)
You cannot retrieve the ABI ...
- 542
3
votes
Stop frontrunner bots by comparing block.number of buy tx versus sell and transfer tx?
I tested this today on BSC network and was successfully able to guard against frontrunner sandwich bots using this method. Honeypot checker did not flag my token.
I doubt any bots would implement this:...
- 31
3
votes
Solidity : Error encoding arguments: Error: invalid BigNumber string
I'm also learning from fcc haha. Not sure if you still need it but just in case if others also encounter similar problem. I don't think you're supposed to change "People[0] public people;" ...
- 31
3
votes
Accepted
Error : Using ".value(...)" is deprecated. Use "{value: ...}" instead
I had faced this on invoking call and had found from Solidity docs that gas and value parameters need to be passed in curly brackets now:
address(nameReg).call{gas: 1000000, value: 1 ether}(abi....
- 126
3
votes
How to encode initializer in gnosis-safe proxy contract?
As proxies canot use the conventional constructor approach, the common way to compensate for this is to provide an initialization function (see OpenZepplin).
To avoid that this can be front-run in a ...
- 5,144
3
votes
Mint nft on Testnet
For testnets you can use address https://testnets.opensea.io/
3
votes
Accepted
ERC20 decimals in smart contract
As explained here, the decimals in an ERC20 token are just for representation to the user. The EVM has nothing to do with it. A wallet that recognizes ERC20 tokens and knows how many decimals a token ...
- 4,649
3
votes
how to add rinkeby test network to metamask
The Rinkeby and Ropsten testnets have been deprecated as of October 5th, 2022.
- 4,308
3
votes
Accessing data of struct in mapping externally
There are 2 issues:
you try calling the getters of the transactions mapping using a wrong syntax: args are between parenthesis, not brackets (ie change multisig.transactions[id] for multisig....
- 1,326
3
votes
Accepted
Can I lock an account to a specific smart contract?
Unfortunately, you can't directly "lock" an EOA (External Owned Account) to only interact with a specific smart contract, as it's not a built-in feature of EVM.
However, you can design a ...
- 2,441
3
votes
Warning! Error encountered during contract execution [invalid opcode: PUSH0
Instead of going back to an older version of Solidity compiler, in hardhat to prevent use of PUSH0 you can try setting evmVersion to a previous version (e.g. paris, which is the one before shanghai) ...
- 153
3
votes
Accepted
How to sign Transactions in smart contract account in erc 4337?
That is the whole point of having smart accounts, to abstract away the need of signing a tx that needs the gas fees in native token.
Smart Accounts just need to send the user Operations, and the tx ...
- 5,320
2
votes
Can someone help me figure out how to get my UNI from an old MCD vault?
Here is what I think that you should do (using web3.js v1.2):
const Web3 = require("web3");
// enter your node address and private key below, for example:
const NODE_ADDRESS = "https://...
- 26.2k
2
votes
Accepted
what is the cheapest way for sending ethereum from 10 account addresses to 10 account addresses?
10 transactions from an EOA will cost 210,000 gas.
The most efficient way to do this would be to deploy a contract that accepts funds in the constructor and subsequently distributes the funds to 10 ...
- 18.3k
2
votes
How to write a smart contract for access level (read/write)?
This might be done in the same manner as any other programming language: you basically define who will assign/revoke these permissions and create a structure to handle such permissions per user (read, ...
- 3,409
2
votes
Accepted
How to call a smart contract function using Nethereum and Infura
It seems that your function checks is the valid owner, hence you have a revert error message Nethereum.JsonRpc.Client.RpcResponseException: execution reverted: Ownable: caller is not the owner. This ...
- 1,405
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