Solidity

在上一篇文章中，我們可以看到?pragma solidity 0.4.9;,

這里的Solidity，就是以太坊智能合約的核心語言Solidity，也是本教程的重點。

Solidity是什么？

Solidity是以太坊智能合約的編程語言，通過編譯&部署智能合約，可以實現智能合約的Create、執行和查看，從而實現某些商業應用。

幾個簡單的Solidity例子

通過以下幾個智能合約，我們可以將一些商業應用很好的區塊鏈化，從而實現去中介、去信任、高度透明的商業模型。

在之后的整個教程中，我們會逐步解析Solidity編程，幫助大家快速掌握Solidity這門語言，并且將區塊鏈落地到前端Web頁面上

I 實現1+2+3+..+n的求和功能

pragma solidity 0.4.9; contract Demo1 {/*計算從1到N的求和*/function f(uint n) returns (uint sum) {if (n == 0) throw; uint result = 0;for (uint i=0; i<=n; i++) {result +=i;}return result;} }

II 實現一個代幣功能，并自帶挖礦和轉移代幣的功能。

pragma solidity ^0.4.0;contract Coin {// The keyword "public" makes those variables// readable from outside.address public minter;mapping (address => uint) public balances;// Events allow light clients to react on// changes efficiently.event Sent(address from, address to, uint amount);// This is the constructor whose code is// run only when the contract is created.function Coin() {minter = msg.sender;}function mint(address receiver, uint amount) {if (msg.sender != minter) return;balances[receiver] += amount;}function send(address receiver, uint amount) {if (balances[msg.sender] < amount) return;balances[msg.sender] -= amount;balances[receiver] += amount;Sent(msg.sender, receiver, amount);} }

III 實現一個眾籌的智能合約，各個用戶可以籌款、籌款成功可以將所得轉讓給受益人，每個參與眾籌者可以獲得代幣。

pragma solidity ^0.4.2; contract token { function transfer(address receiver, uint amount){ } }contract Crowdsale4 {address public beneficiary;uint public fundingGoal;uint public amountRaised;uint public deadline;uint public price;token public tokenReward;mapping(address => uint256) public balanceOf;bool public fundingGoalReached = false;event GoalReached(address beneficiary, uint amountRaised);event FundTransfer(address backer, uint amount, bool isContribution);bool public crowdsaleClosed = false;/* data structure to hold information about campaign contributors *//* at initialization, setup the owner */function Crowdsale4 (address ifSuccessfulSendTo,uint fundingGoalInEthers,uint durationInMinutes,uint etherCostOfEachToken,token addressOfTokenUsedAsReward) {beneficiary = ifSuccessfulSendTo;fundingGoal = fundingGoalInEthers * 1 ether;deadline = now + durationInMinutes * 1 minutes;price = etherCostOfEachToken * 1 ether;tokenReward = token(addressOfTokenUsedAsReward);}/* The function without name is the default function that is called whenever anyone sends funds to a contract */function () payable {if (crowdsaleClosed) throw;uint amount = msg.value;balanceOf[msg.sender] += amount;amountRaised += amount;tokenReward.transfer(msg.sender, amount / price);FundTransfer(msg.sender, amount, true);}modifier afterDeadline() { if (now >= deadline) _; }/* checks if the goal or time limit has been reached and ends the campaign */function checkGoalReached() afterDeadline {if (amountRaised >= fundingGoal){fundingGoalReached = true;GoalReached(beneficiary, amountRaised);}crowdsaleClosed = true;}function safeWithdrawal() afterDeadline {if (!fundingGoalReached) {uint amount = balanceOf[msg.sender];balanceOf[msg.sender] = 0;if (amount > 0) {if (msg.sender.send(amount)) {FundTransfer(msg.sender, amount, false);} else {balanceOf[msg.sender] = amount;}}}if (fundingGoalReached && beneficiary == msg.sender) {if (beneficiary.send(amountRaised)) {FundTransfer(beneficiary, amountRaised, false);} else {//If we fail to send the funds to beneficiary, unlock funders balancefundingGoalReached = false;}}} }

Solidity的簡介就到此為止了，后面我們會具體解析這些合約的奧秘

前面說過，智能合約是部署在以太坊的網絡上的，那么如何搭建一個以太坊網絡呢，就需要官方提供的工具Geth了。下一章會詳細說明。

原文地址：?http://www.ethchinese.com/?p=630

總結

以上是生活随笔為你收集整理的区块链学堂（3）：Solidity的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。