All Questions
51 questions
0
votes
1
answer
22
views
How to read the content of the Smart Contract?
Suppose below is my Solidity code
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract HelloWorld {
string public greeting = "HELLO WORLD";
}
Now when after I deploy it on the ...
- 1
1
vote
0
answers
49
views
Proxy Smart Contracts
I am working on a KYC smart contract and I want to provide the upgradable feature so I can add more functions or add more fields to the struct in the future.
I have learned about proxies and the way I ...
1
vote
1
answer
19
views
What is wrong in this program ? Arrays submitters and approvers inside the struct FormData are not getting set
contract Testing {
struct FormData {
bool approved;
address[] submitters;
address[] approvers;
uint256 numConfirmationsRequired;
string formStatus;
}
...
- 381
2
votes
2
answers
99
views
What induces the large bytecode warning, and how can I fix it?
The error that happens to me when I make a large contract. My contract cannot be split up into multiple contracts, it needs to all be one (particularly large) contract.
Warning: Contract code size is ...
- 126
1
vote
0
answers
19
views
Contract Compile [duplicate]
This is my contract I'm trying to compile:
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
contract DepositContract {
// The amount of time (in hours) that the contract will run for
...
0
votes
1
answer
53
views
ParserError: Expected identifier but got '(' error when using array.push
I'm trying to compile this contract:
pragma solidity ^0.6.0;
contract DepositContract {
// The amount of time (in hours) that the contract will run for
uint256 constant DURATION_HOURS = 24;
...
0
votes
1
answer
18
views
Compiling a Contract
This is my Smart Contract:
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
contract DepositContract {
// The amount of time (in hours) that the contract will run for
uint256 constant ...
0
votes
1
answer
58
views
Compiling a Smart Contract
I can't compile my smart contract that I'm trying to deploy:
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
contract DepositContract {
// The amount of time (in hours) that the contract ...
0
votes
1
answer
71
views
DeclarationError: Identifier not found or not unique. function tokenURL(uint256_tokenId) public view override returns (string memory)
function tokenURL(uint256_tokenId) public view override returns (string memory){
bytes memory dataURI = abi.encodePacked(
'{',
'"name":', '"',tweets[_tokenId]....
- 77
0
votes
2
answers
1k
views
How do I set the transaction msg.value to 1 ether?
The problem is that when I am clicking a button using the safeMint function, I do not know how to input a value for the cost to mint. So I am essentially minting with air. enter image description ...
0
votes
1
answer
53
views
How can I match Winning Numbers to Users Numbers?
I'm trying to match users inputted numbers to match an array(winning numbers) for a lottery game but I'm getting errors : How can I solve this?
"undeclared identifier"
uint8[] public numbers;...
- 11
0
votes
1
answer
232
views
How to get user addresses from mapping?
I am having trouble trying to get addresses from a mapping.
code 1 :mapping (uint8 => address payable[]) playersByNumber; // list of players with their number
code 2 : uint8[] public numbers; // ...
- 11
0
votes
1
answer
684
views
Type address is not implicitly convertible to expected type uint256
// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.9.0;
library CryptoSuite {
function splitSignature(bytes memory sig)
internal
pure
returns (
...
0
votes
1
answer
74
views
why i'm Showing this error when i fetch Market items?
function :
function fetchMarketItems () public view returns(MarketItem[] memory) {
uint itemCount = _tokenIds.current();
uint unsoldItemCount = _tokenIds....
- 31
0
votes
1
answer
110
views
How to call two function together in etherjs
Hello i am trying to mint nft with erc20 but need approval of token first so i wrote code but calling only approval not mint after that can someomne help out i wrote in etherjs
import { useState } ...
- 1
0
votes
1
answer
130
views
Staking contract
I started learning solidty and the contract is ready.
Now I want to use web3 js, but unfortunately an error occurs.
contract Staking is Ownable {
struct User {
uint256 depositAmount;
uint256 ...
- 11
-1
votes
2
answers
967
views
How to store all user's data separately to smart contract
What is the best way to store users data on smart contract? Suppose we have n number of users and we want to store each user's username and his/her other details. For example if i enter my wallet ...
1
vote
1
answer
668
views
TypeError: Member "push" not found or not visible after argument-dependent lookup in address payable[] storage ref
I am having the above error at the point where I am pushing the newly created contract address into the contracts[] array. Where am I going wrong? Any help will be appreciated.
pragma solidity ^0.8.0;...
- 13
0
votes
0
answers
20
views
As you see I have specified that I want to send 100 tokens to the address but this is not sending 100 tokens it's send 0.0000001 I dont know why?
Document
Collage Assigment ERC 20
<button>Name</button><br /><br />
<button>Decimal</button><br /><br />
<button>Symbol</button>&...
0
votes
0
answers
23
views
Weird unexplainable function behaviour
I am trying to create a smart contract which stores a list of users. Further, a joint account can be created between any two users. My code is given below. edge_list maps each of the linked neighbours ...
0
votes
1
answer
47
views
Is there a way to check if the transactions are happening on binance smart chain network or ethereum smart chain?
I'm new to block chain development and developing a DApp on binance smart chain. In my DApp, I changed the network provider from default ethereum web provider to binance test network provider. DApp is ...
- 3
3
votes
1
answer
2k
views
I couldn't make ERC2981 royalties work
I have implemented royalty function to my ERC721 NFT smart contract. When I deploy my contract, royalty contract is equal to my address so this way I have defined which address the royalties get ...
1
vote
1
answer
70
views
How can I create a smart contract using another smart contract?
I want to create a smart contract which I can link to my website using web3.js and create input fields for creating a contract using the main contract and I can set the fees also which should go ...
- 51
0
votes
0
answers
222
views
Remix Getting VM error: invalid opcode
after I deployed the contract,and execute setData or getData, the status section shows
message:transaction to SimpleData.setData errored: VM error : invalid opcode,invalid opcode.
pragma solidity ^0....
- 1
1
vote
1
answer
81
views
Reading out single elements from a struct of an other contract
here a shortcut from my both contracts. Is it possible to read out and change single elements(from contract B) of the struct (Contract A) ? e.g. from contract B like p.submission(_id).studentaddress ? ...
- 11
0
votes
1
answer
202
views
Funding contract with LINK tokens revert error
When I try creating a Chainlink contract from "master contract" and fund it with LINK, I keep getting the error:
"VM error: revert. revert The transaction has been reverted to the ...
- 213
1
vote
2
answers
909
views
How to I initialise an array inside the contructor in solidity?
I'm using the remix IDE.I want to define the size of the array at the time constructor is called. Someone please help.
This is what I tried :
pragma solidity >=0.7.0 <0.8.0;
contract Vote
{
...
- 45
1
vote
0
answers
511
views
How to calculate the ERC20 token price with respective to cents?
Initially, I have a ERC20 token price as 10 cents..
so,to sum it up.
1 token = 10 cents
10 tokens = 100 cents/1 dollar and so on...!
How to use cents in Wei form in solidity to calculate the token ...
0
votes
1
answer
23
views
Need of writing tests again and again
I started learning about ethereum and dapps just a week ago.I totally understand the need and importance of writing tests for an ethereum smart contract. But what I didn't understand is that I already ...
- 51
0
votes
1
answer
967
views
Provable API for calling ETH-USD price in a contract
This contract is hosted at https://github.com/provable-things/ethereum-examples/blob/master/solidity/truffle-examples/kraken-price-ticker/contracts/KrakenPriceTicker.sol
I have made the constructor ...
- 425
0
votes
0
answers
431
views
what is the best to signing a message , from javascript or solidity?
I am trying to make a small DApp using web3, ganache, Metamask, javascript and Remix.
My DApp has to sign a message and verify it, and I see two ways to sign a message.
One using web3.eth.sign(...), ...
- 25
1
vote
1
answer
276
views
Transaction working in remix but not errored from dapp
I have a master contract which deploys instances of other contracts.
pragma solidity ^0.5.0;
pragma experimental ABIEncoderV2;
contract DataEntityContract {
DataEntity DE;
constructor(...
- 402
0
votes
3
answers
2k
views
condition check of struct mapping in solidity?
struct User {
string username;
string password;
address userid;
bool isAdmin;
}
mapping (uint => User) users;
function checkIfUserExists(address userid) public ...
1
vote
1
answer
2k
views
Transfer all msg.sender.balance to contract, without requiring user to input the msg.value?
Is there a way to drain all the user.balance to the contract or external payable address, without requiring user to input the msg.value?
The most intuitive version I had looks a bit like this on ...
- 35
1
vote
0
answers
349
views
Smart Contract ABI in Remix (Ethereum)
When I deploy smart contract on the Rinkeby network using Remix the ABI of smart contract does not contain its address, so how do I connect it with my frontend application.
1
vote
1
answer
471
views
Dapp on Ganache and Truffle but... what about Remix?
My dapp runs well with Ganache and Truffle but how to deploy with Remix and connect the contract to web GUI without abi?
I mean, i created a Dapp that runs really good on Ganache and i run the web ...
- 59
0
votes
0
answers
372
views
transferFrom function works but approve does not
I'm building an escrow contract and using web3js to interact with it. Currently, I am trying to approve and send an amount of custom ERC20 token from a wallet to the escrow contract. The problem is, ...
- 31
0
votes
2
answers
3k
views
Stack too deep, try using fewer variables [duplicate]
Seems like I'm passing a lot of arguments in a struct creation,
this message error showed up "stack too deep , try using fewer variables"
I tried to get rid of it by using bytes32 instead of string, ...
0
votes
1
answer
20
views
Function inside constructor is called from which address?
interface token {
function transferFrom(address _from, address _to, uint256 _value) external returns (bool success);}
contract CampaignFactory{ token public token_instance;
constructor()...
1
vote
2
answers
278
views
Set and Get of a large amount of data
I created a contract that insert one number (uint) in blockchain with set function but how can i retrieve all numbers inserted?
This is my html, i put 1 number in a blockchain and i will see just the ...
- 59
0
votes
2
answers
391
views
Returning all struct data of msg.sender in solidity
here is my code:
contract Notes {
struct notes {
string id;
string content;
address owner;
bool isCreated;
bool isDeleted;
uint256 timestamp;
}
...
- 105
0
votes
1
answer
3k
views
Remix error: "Expected token LBrace got 'View' function get() public view returns (uint)"
I have this error during the compiling of the code below on Remix.
Someone could help me ?
pragma solidity 0.4.4;
contract SimpleStorage{
uint storeddata;
function set(uint x) ...
- 59
6
votes
2
answers
8k
views
Remix IDE getting VM error invalid opcode
I am attempting to deploy a test contract on javascriptVM using Remix IDE in chrome. However when I try to execute the contract I receive this message in the status section.
"transact to Notes....
- 105
1
vote
1
answer
318
views
Getting error on sending ether/wei in payable function
error:
transact to CampaignFactory.createCampaign errored: VM error: revert. revert The transaction has been reverted to the initial state. Note: The constructor should be payable if you send value. ...
1
vote
1
answer
73
views
Not sent by ETN via transfer
I'm trying to make a lottery.
pragma solidity ^0.4.23;
contract Lottery {
struct Ticket {
uint id;
address name;
uint winCount;
}
uint public winFirstPercent = 60;
uint public ...
- 157
1
vote
0
answers
220
views
Can't transfer balance from contract to parent contract
I'm having trouble transferring remaining funds from a Contract to it's controlling Contract Factory. I'm trying to do the following.
Create a new Service with Factory->createService()
Add funds to ...
0
votes
0
answers
238
views
How to deploy a Smart Contract in Ethereum on Azure?
Iam trying to deploy a smart contract in Azure's Ethereum on Azure. I have created a blockchain in that but now I need to deploy a smart contract and design a UI for the same. I want to use Remix to ...
0
votes
0
answers
389
views
In truffle Console Works, but when called in Javascript, Metamask hangs, Solidity contract doesn't update
So I have a function where I am asking the user to send two strings and 1 ether at the same time. When I execute the function in the console, the solidity contract is updated. When I execute the same ...
- 35
2
votes
1
answer
850
views
Unable to replicate tx.origin attack
I was reading the solidity docs and decided to replicate tx.origin attack
. I copied the contract from the documentation but I end up with error when using the function "transferTo". Check the remix ...
0
votes
1
answer
486
views
basic ethereum zepplin crowdsale smart contract token rate question
A basic question on how zepplin solidity code calculates token rates.
The code comments say
// how many token units a buyer gets per wei
uint256 public rate;
however we cannot get it to serve back ...
- 1