Basic Crowdsale Contract

Question

I am learning to develop smart contract using Solidity. Currently, I am working and test the feature of following crowdsale contract.

https://github.com/OpenZeppelin/openzeppelin-solidity/blob/v1.8.0/contracts/crowdsale/Crowdsale.sol

This contract constructor has three different values.

1. rate
2. wallet address
3. token address

I am confused about the first one that is "rate". what value should i have to pass here ?

for example, I want to sell 1 token at cost of 1 ether then what should i pass here ?

Answer 1

As you can see the function

function _getTokenAmount(uint256 _weiAmount) internal view returns (uint256) {
    return _weiAmount.mul(rate);
  }

It states that for 1 wei, the no of tokens will be 1*rate.

for example, I want to sell 1 token at cost of 1 ether then what should i pass here ?

This depends on number of decimals in your toke contract. For eg, if you have 18 decimals,then

token = wei * rate

1 Token = 1 ether * rate

10 ^18 token = 10 ^18 wei * rate

=> rate = 1

Answer 2

http://eth-converter.com/

Wei to Ether

Wei is the 18 digits that go into an Ether

Answer 3

Rate is explained in the OpenZeppelin Contracts Crowdsale documentation: https://docs.openzeppelin.com/contracts/2.x/crowdsales#crowdsale-rate

You can also ask questions about how to use OpenZeppelin Contracts in the Community Forum

Disclosure: I am the the Community Manager at OpenZeppelin