Ethereum Ðapp Development - Video 15 | The Block Gas Limit

crowdfund.sol

contract CrowdFund {

  address public beneficiary;
  uint256 public goal;
  uint256 public deadline;

  struct Funder {
    address addr;
    uint256 contribution;
  }

  Funder[] funders; 

  function CrowdFund(address _beneficiary, uint256 _goal, uint256 _duration) {
    beneficiary = _beneficiary;
    goal = _goal;
    deadline = now + _duration;
  }

  function contribute() payable {
    funders.push(Funder(msg.sender, msg.value));
  }

  function payout() {
    if(this.balance >= goal && now > deadline) beneficiary.send(this.balance);
  }

  function refund() {
    if(msg.sender != beneficiary) throw;
    uint256 index = 0;
    while(index < funders.length) {
      funders[index].addr.send(funders[index].contribution);
      index++;
    }
  }

}