區(qū)塊鏈技術(shù)概括起來是指通過去中心化和去信任的方式集體維護(hù)一個(gè)可靠數(shù)據(jù)庫的技術(shù)。其實(shí)，區(qū)塊鏈技術(shù)并不是一種單一的、全新的技術(shù)，而是多種現(xiàn)有技術(shù)整合的結(jié)果，這些技術(shù)與數(shù)據(jù)庫巧妙地組合在一起，形成了一種新的數(shù)據(jù)記錄、傳遞、存儲(chǔ)與呈現(xiàn)的方式

　　//Contract to sell and distribute VEN tokens

　　contract VENSale is Owned{

　　///chart of stage transition

　　///

　　///deploy initialize startTime endTime finalize

　　///|<-earlyStageLasts->||<-closedStageLasts->|

　　///Created Initialized Early Normal Closed Finalized

　　enum Stage{

　　NotCreated,

　　Created,

　　Initialized,

　　Early,

　　Normal,

　　Closed,

　　Finalized

　　}功能及邏輯技術(shù)I59系統(tǒng)2OO7開發(fā)3O69

　　using SafeMath for uint256;

　　uint256 public constant totalSupply=(10**9)*(10**18);//1 billion VEN,decimals set to 18

　　uint256 constant privateSupply=totalSupply*9/100;//9%for private ICO

　　uint256 constant commercialPlan=totalSupply*23/100;//23%for commercial plan

　　uint256 constant reservedForTeam=totalSupply*5/100;//5%for team

　　uint256 constant reservedForOperations=totalSupply*22/100;//22 for operations

　　//59%

　　uint256 public constant nonPublicSupply=privateSupply+commercialPlan+reservedForTeam+reservedForOperations;

　　//41%

　　uint256 public constant publicSupply=totalSupply-nonPublicSupply;

　　uint256 public constant officialLimit=64371825*(10**18);

　　uint256 public constant channelsLimit=publicSupply-officialLimit;

　　//packed to 256bit

　　struct SoldOut{流程及詳情：yy625019

　　uint16 placeholder;//placeholder to make struct pre-alloced

　　//amount of tokens officially sold out.

　　//max value of 120bit is about 1e36,it's enough for token amount

　　uint120 official;

　　uint120 channels;//amount of tokens sold out via channels

　　}

　　SoldOut soldOut;

　　uint256 constant venPerEth=3500;//normal exchange rate

　　uint256 constant venPerEthEarlyStage=venPerEth+venPerEth*15/100;//early stage has 15%reward

　　uint constant minBuyInterval=30 minutes;//each account can buy once in 30 minutes

　　uint constant maxBuyEthAmount=30 ether;

　　VEN ven;//VEN token contract follows ERC20 standard

　　address ethVault;//the account to keep received ether

　　address venVault;//the account to keep non-public offered VEN tokens

　　uint public constant startTime=1503057600;//time to start sale

　　uint public constant endTime=1504180800;//tiem to close sale

　　uint public constant earlyStageLasts=3 days;//early bird stage lasts in seconds

　　bool initialized;

　　bool finalized;

　　function VENSale(){

　　soldOut.placeholder=1;

　　}