19
votes
Accepted
How to impose a timelock || Vesting for ERC20 tokens during ICO(Crowdsale)
Vesting with a cliff is a typical requirement for founders holding shares of a company so they don't just leave the company when they are most needed with the shares they have. The same concept has ...
- 7,456
18
votes
what is the difference between hard cap and soft cap in ethereum ICO
A hard cap is defined as the maximum amount a crowdsale will receive. Most projects set a very high cap that is unlikely to happen. Only very famous projects like Status or Brave browser have reached ...
- 30k
10
votes
Accepted
Send ether to contract address in web3.js
If you want to accept the Ether in a smart contract then you should have a fallback function. The fallback function will be called by default when someone transfers ETH to the contract address.
...
- 1,136
10
votes
Accepted
Smart Contract to receive tokens and give ether?
It's slightly more complicated because users don't just send you tokens. They have to first give you allowance to spend the token, then they call your function (say tokenToEther())
First your user ...
- 1,318
7
votes
Accepted
Crowdsales: non-mintable tokens vs mintable tokens (with hard cap)
Yup, its the same - but if you give 10 developers the same problem you could get 10 different ways of solving it.
Its interesting though, if you think about it - Ethereum actually rewards users of ...
- 636
6
votes
Accepted
Error encountered, bailing. Network state unknown. Review successful transactions manually
The origin of the issue is because you're trying to deploy the contract from the file migrations/1_initial_migration.js that is supposed to be used only for the deployment of Migration.sol.
To deploy ...
- 7,027
5
votes
how to setup multicurrency ICO / Crowdsale
An Ethereum contract cannot directly interact with other blockchains.
You have to use a service like BTC Relay, their project on github.
- 30k
4
votes
How can I create a Dashboard for my Ethereum ICO investors to track their Tokens
I would suggest you using NodeJS and web3js library to interact with ethereum. It would not be really hard to get into NodeJS of you are a web developer.
My team and I opened a source code of the ...
- 196
4
votes
Interacting with a deployed contract: How can I mint a token based on the Open Zeppelin Standard
Have a look at Interacting with smart contracts using truffles.
If you deployed your smart contract with the name SampleCrowdsale, for example with
var mycrowdsale = SampleCrowdsale.deployed();
...
- 1,375
4
votes
Is it possible to create ICO crowdsale seamlessly accepting multiple assets?
This is only a partial answer to your question. One issue you would face is that deposits by people who buy your tokens with BTC or any other cryptocurrency besides ETH would have to be credited ...
- 2,259
4
votes
Accepted
TxReceipt Status fail sending ETH to Contract on Rinkeby
We had some of the same problems as you did. What we figured out was the following:
startTime and endTime must be set so that when you call the
contract, you are in fact buying tokens when the sale ...
- 464
4
votes
Error encountered, bailing. Network state unknown. Review successful transactions manually
Check any abstract/interface methods are being implemented correctly. I get this issue, where it compiles but won't deploy, when I fail to implement abstract/interface methods correctly in inheriting ...
- 1,638
4
votes
Invalid implicit conversion from address to address payable requested
Okay i understand know the reason why the tutorial code work and your code doesn't work is because of this is because in new solidity the CrowdSale is actually:
constructor (uint256 rate, address ...
- 1,064
3
votes
Risk of attack if you give more than the half of your tokens?
You should clarify what you mean by an attack. If you are using your tokens as a mean to get consensus from all the token holders than yeah, owning more than 50% of the tokens effectively means they ...
- 191
3
votes
Finally my first Token - questions
All the transfers seem to have the same from and to address (the token contract). I believe the issue is this line in buyTokens:
ERC20(token).transfer(this, tokens);
Shouldn't that read as follows?
...
- 27.4k
3
votes
Accepted
What is an example of an ICO or Crowdsale that used the Open Zeppelin RefundVault contract?
For example, when you create a new RefundVault inside of the crowdsale
you pass in an address in the constructor. What address should this
be?
That's the crowdsale's wallet address.
The ...
- 417
3
votes
Make a crowdsale reusable?
This sounds like a perfect use case for the now finalized ERC-1155 token standard, which allows one to manage any number of fungible and non fungible tokens in a single contract.
- 31
2
votes
Accepted
Is ICO a crowdsale or decentralized organization?
ICO: Initial coin offering: Doesn't have anything to do with an organization. It can be used by an organization to reward their tokens to members that contribute.
- 367
2
votes
Accepted
Crowdsale contract and safe withdrawals
Has anybody used this code to crowdsale tokens and perform a withdrawal as a user?
IMO that code is more a sketch of an actual ICO and not meant as a secure and proper ICO reference implementation. ...
- 8,404
2
votes
Is that a need to add every investors to multisig wallet?
The investors are not owners of the multisig, the founders of the project are.
The standard is for the token contract to implement ERC20 such that investors can transfer their tokens (etc).
...
- 4,255
2
votes
Accepted
How to transfer ETH from contract to external address after crowsale?
You've possibly provided too little information to really be helpful.
Can you post the contract's address and the parameters used to create it?
address ifSuccessfulSendTo =
uint ...
- 625
2
votes
How reliable is it to use Block number to calculate Time in Smart contract?
Yes, of course. Both block timestamp and block number are equally reliable. There is an entire alarm clock system built in ethereum for executing something at a later stage. For more info on that you ...
- 584
2
votes
Accepted
Where to place in Zeppelin crowdsale variables
SampleCrowdsale is the contract constructor. It is called automatically when the contract is created. You can tell it is the constructor because the name of the method is the same as the name of the ...
- 472
2
votes
In the example Ethereum crowdsale contract, what is the safe withdrawal function?
These are the relevant parts:
modifier afterDeadline() { if (now >= deadline) _; }
and
function safeWithdrawal() afterDeadline {
if (!fundingGoalReached) {
uint amount = balanceOf[...
- 11.5k
2
votes
Accepted
Risk of attack if you give more than the half of your tokens?
Just to add to the answerof cappy, it seems you are getting confused between an attack at the ethereum network level and an attack against your contract.
When we talk of 51pct attack, its generally ...
- 574
2
votes
Risk of attack if you give more than the half of your tokens?
Is your tokens following ERC20? If yes, it is not necessary to have a minimun amount to avoid attacks. Design patterns are good because it is well used and tested. As I said, if you are following ...
- 1,024
2
votes
Can the variables in a crowdsale contract be modified in future?
That depends on the contract code. If the contract has functions that change the variables holding these parameters then it's possible to change them. So it's highly recommendable to look at the code ...
- 1,751
2
votes
Error: VM Exception while processing transaction: invalid opcode
One of the problems could be that you are setting tokenReward (the address of the token you will be using for distribution) to be one of the eth accounts, which is an externally owned account (a user)....
- 7,456
2
votes
Questions about Crowdsale contract
1: It should be 10 million multiplied by the decimals, so:
uint256 constant INITIAL_SUPPLY = 10000000 * 10** uint(decimals);
2: It is unrelated to whether or not the tokens are mintable. The ...
- 7,456
2
votes
Crowdsale - Balance declaration error
In HEY you wrote:
function StandardToken() public {
balance[msg.sender] = INITIAL_SUPPLY;
}
But the variable name is balances, not balance.
- 7,456
Only top scored, non community-wiki answers of a minimum length are eligible