Ethereum Cookbook

How to do it…

1. Create a crowdsale contract that can be used for the Initial Coin/Token Offering process. Import SafeMath for arithmetic operations:

pragma solidity ^0.4.23;import "./math/SafeMath.sol";contract CrowdSale {    // ..}

2. If you are distributing tokens to investors, then import the token contract and create a state variable to keep the address of the distributable token contract:

pragma solidity ^0.4.23;import "./math/SafeMath.sol";import "./ERC20.sol";contract CrowdSale {    // The token sold through the ICO    ERC20 public token;}

3. Tokens sold for each purchase are calculated at a rate; create a state variable to store it in the contract. The rate parameter stores the number of tokens the buyer gets for a Wei:

uint256 public rate; ...