说明
错误的使用了this.balance, 与 selfdestruct()函数
（我也没看明白）
例子：
contract EtherGame {
uint public payoutMileStone1 = 3 ether;
uint public mileStone1Reward = 2 ether;
uint public payoutMileStone2 = 5 ether;
uint public mileStone2Reward = 3 ether;
uint public finalMileStone = 10 ether;
uint public finalReward = 5 ether;
mapping(address => uint) redeemableEther;
// users pay 0.5 ether. At specific milestones, credit their accounts
function play() public payable {
require(msg.value == 0.5 ether); // each play is 0.5 ether
uint currentBalance = this.balance + msg.value;
// ensure no players after the game as finished
require(currentBalance <= finalMileStone);
// if at a milestone credit the players account
if (currentBalance == payoutMileStone1) {
redeemableEther[msg.sender] += mileStone1Reward;
}
else if (currentBalance == payoutMileStone2) {
redeemableEther[msg.sender] += mileStone2Reward;
}
else if (currentBalance == finalMileStone ) {
redeemableEther[msg.sender] += finalReward;
}
return;
}
function claimReward() public {
// ensure the game is complete
require(this.balance == finalMileStone);
// ensure there is a reward to give
require(redeemableEther[msg.sender] > 0);
redeemableEther[msg.sender] = 0;
msg.sender.transfer(redeemableEther[msg.sender]);
}
}
解决办法
contract EtherGame {
uint public payoutMileStone1 = 3 ether;
uint public mileStone1Reward = 2 ether;
uint public payoutMileStone2 = 5 ether;
uint public mileStone2Reward = 3 ether;
uint public finalMileStone = 10 ether;
uint public finalReward = 5 ether;
uint public depositedWei;
mapping (address => uint) redeemableEther;
function play() public payable {
require(msg.value == 0.5 ether);
uint currentBalance = depositedWei + msg.value;
// ensure no players after the game as finished
require(currentBalance <= finalMileStone);
if (currentBalance == payoutMileStone1) {
redeemableEther[msg.sender] += mileStone1Reward;
}
else if (currentBalance == payoutMileStone2) {
redeemableEther[msg.sender] += mileStone2Reward;
}
else if (currentBalance == finalMileStone ) {
redeemableEther[msg.sender] += finalReward;
}
depositedWei += msg.value;
return;
}
function claimReward() public {
// ensure the game is complete
require(depositedWei == finalMileStone);
// ensure there is a reward to give
require(redeemableEther[msg.sender] > 0);
redeemableEther[msg.sender] = 0;
msg.sender.transfer(redeemableEther[msg.sender]);
}
}