Questions tagged [function]

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Help with cycle function in Ethereum Blockchain

I am trying to understand the use of a particular function: cycle(uint256 vaultId, uint256[] _desiredIds, uint256 maxIterations, bool acceptAny) What is the purpose of this function? Why is called? I ...
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Create contract with contract

I want to create a contract that can create contract itself I find something like this pragma solidity ^0.5.0; contract DaughterContract { string public name; uint public age; constructor( ...
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How to reset all addresses in a mapping assigned a uint256 counter

apologies if I'm not using the correct language to describe what I am trying to accomplish. I'm looking for a solution to reset the "idcounter" to 0 across all addresses, so that they can ...
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Pure function that reads from storage, compiler bug?

I just came across this while testing around with the Diamond Storage pattern. Here is a 'pure' function that reads from storage. This had me wondering, is there actually any difference between pure ...
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Gas estimation reverts

I am quite new to blockchain programming and am trying to estimate the gas cost of calling a function from a smart contract. I am using Web3 js and the Kovan network through an Infura node. What am I ...
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Passing different data types to uint parameter

I found out, that I can pass different data types (as argument), even if the Solidity method takes only uint data type, why is that possible? Example: function test (uint _param) public { //do smth ...
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Looking for data in Smart contract

// SPDX-License-Identifier: MIT pragma solidity ^0.8.3; contract Storage { struct People { uint256 personId; string vorname; string nachname; uint256 birthdate; ...
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Appending an item into an array inside a struct

Working on solidity 8.12, I have two structs, namely singer and event, two arrays one for singers and another for events. I want to write down a function that creates an event, specifying the singer ...
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How to test the Solidity-By-Example Mapping smart contract in Remix?

I want to test the following code in Remix. But what is the procedure? What do I put in the input field for the function labeled set? Mapping.sol // https://solidity-by-example.org/mapping // Mapping /...
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Different number of parameters between client and contract functions

From this repository: https://github.com/dabit3/polygon-ethereum-nextjs-marketplace Look at createToken function inside the JavaScript file (pages/create-nft.js): let listingPrice = await contract....
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Why and when to user require(bool) on functions

I want to understand when (and why) it's necessary to use this statement : require(sent, "failed to send ether") i could just do somethink like this instead:
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can we call constructor in another function of the same contract in solidity?

can we call constructor in another function of the same contract in solidity ? Curious, Kindly reply asap. Thanks
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If not in the EVM, where do internal functions execute?

The Ethereum documentation says that internal functions are not executed in the EVM, while external ones are: If not in the EVM, where are internal functions executed? Does this simply mean that ...
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if-else in Solidity Doesn't Work

Im creating a web based medicine anticounterfeit using blockchain and this is my smart contact program: // SPDX-License-Identifier: MIT pragma solidity ^0.6.0; contract SupplyChain { event ...
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Solhint: Why should I avoid multiple calls of "send" in a single transaction?

function withdrawAll() public payable onlyOwner { uint256 _each = address(this).balance / 4; require(payable(t1).send(_each), "Account is being paid out"); require(payable(t2)....
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Which function calls `AtomicMatch` is called by in opensea source code

I am trying to figure out how to call the function AtomicMatch in opensea. Currently I found it is related to function executeCall (https://github.com/wyvernprotocol/wyvern-v3/blob/master/contracts/...
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auto generated functions by solidity

send and transfer are automatically generated function to send ether(wei) to some address. I tried to search a list of such functions in solidity documentation but to no avail, can someone help here? ...
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When I call a contract's view function. Where does the code run?

Does it get executed on my browser by metamask with data requested from a node? Or does the node runs it?
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Distinguish between function calls from externally owned accounts, and from another smart contracts

I wanted to know how to distinguish between a function call from an externally owned user account and a function call from another smart contract in solidity. Can anyone help me with this?
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Does it make a difference using multiple setter functions vs a single generic one?

Let's say I have an enum and set the default: enum Status { INACTIVE, FAIL, SUCCESS, PENDING } Status public myStatus = Status.INACTIVE; I'm wondering if one approach to updating ...
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Remix IDE, Solidity: Function command not showing up inside deployed contract?

Why does the 'withdraw' function not show up in the contract? Using freecodecamp tutorial on remixIDE Here is my code.... pragma solidity >=0.6.6 <0.9.0; import "@chainlink/contracts/src/v0....
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Can access to base URI allow users to anticipate rare NFT by looking at json files?

I've been looking at some NFT Smart Contract functions and I noticed that there were a function that allows access to the base URI, which can basically be the address where the .json files (including ...
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Is it possible to decrypt a signed message given public or private key and message's signature?

a smart contract's function requires a certificate input that should be created using a signed message by the relevant wallet which will call that function. Is it possible to decrypt that signed ...
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very important interface need help

the balance not change from another contract pragma solidity ^0.8.10; interface ICounter { function balanceOf(address owner) external view returns (uint); function transfer(address to, uint ...
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Values added inside of an object that are not parameters of the function

I've seen this in Solidity several times, but I can't find it in the documentation nor do I know how to describe it in a search engine. Say you have a function: function buyItem(uint256 _upc) ...
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What does {...} as a part of a function call mean?

In the function swapExactETHForTokens of Uniswap is called like this: uniswap.swapExactETHForTokens{value: msg.value}( amountOut, path, msg.sender, ...
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How do I change smart contract state with web3.js?

I am using web3.js to interact with a smart contract. I can read values, but I can't change the state with setting functions in the contract. contract MyContract { uint number; function ...
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ClaimTo function in smart contract

I want to pick up tokens from smart contralkt. I want the tokens to be transferred to another address immediately. Can I do it through the ClaimTo function, if so, what additional costs will be ...
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how to add pre-mint function (free mint open to everyone with limit of mint)

I am trying to write a function that would allowed the first 2000 mint are free and then the contract stop until i start the public mint. it would be be like two public mint, i guess. thank you in ...
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What the this keyword means?

im doing the ethernaut course. what does this mean ? I know what for exemple address(this)means, it s the address of the smart contract but like what does it means when the this is alone like this?
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Best practice for calling function from another contract

I'm a bit of a beginner so I'm sorry if I misphrase anything, but I haven't been able to find a definitive answer on this yet. I'm going through some tutorials which list out a few ways to call ...
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Perform an internal function from outside the contract

A few weeks ago I read a comment here on the forum with a link to an article that said it was possible to perform a function marked as internal from outside the contract. That is, it is possible ...
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What is a valid regular expression for a solidity variable or function?

Say I have a function or variable(either one doesn't really matter since functions and variables can have the same names) called foo, how do I test using a regular expression that this function/...
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Is a function like that possible? (Burn/swap)

Good morning everyone, I’m starting smart contract dev and I have a lot of questions. But the biggest question I have is I have one idea in head and I don’t know if it’s possible. To explain: You have ...
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Solidity: Restrict access to functions

Today I found a contract on etherscan providing a restriction on one of the two existing "withdraw" methods and I asked myself: If you would call this function withdraw() as not the owner, ...
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Correct terminology for referring to a specific function of a specific contract

Is there a preferred way of referencing a function of a contract in English? For example, suppose I want to say to someone "to learn more, call the contractInfo function on the contract with ...
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When to use memory and when not to use?

I watched this video and he uses memory a lot like function verify(address _signer, string memory _message, bytes memory _sig. Why so? Could the function work without using memory? While the usual ...
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Does a double space have an effect inside function declaration?

function doSomething(uint256 _someAmount) external { I accidentally made a double space between uint256 and _someAmount Does this make any difference, or is it okay? Do these 2 lines work the same ...
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What happens if a function that is not defined as a view, doesn't change the data of the contract?

example: function addAllowedTokens(address _token) public onlyOwner { if (!tokenIsAllowed(_token)) { allowedTokens[_token] = true; } } In this code, the allowedTokens ...
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Why can't I access the Uniswap v3 Factory .getPool() function?

As a personal exercise, I am trying to convert the following Uniswap v2 project to Uniswap v3: Uniswap token price monitoring (this is not swapping), i.e. ETH/DAI https://www.youtube.com/watch?v=...
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DAO like functionality on Gnosis?

I am a Gnosis newbie. Want to set up a safe for an investor group. It seems like the safe has awesome functionality for that. As the group potentially expands beyond my small circle, may offer ...
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Is there an EVM compiler that supports coroutines? (e.g. generator functions)

With coroutine I mean a subroutine that can be paused and resumed from another subroutine; preserving its internal state across pauses and resumes. For example, a feature similar to: Javascript's ...
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