solidity 教程链接

1. 源文件结构

源文件中可以包含任意多个合约定义、导入源文件指令、版本标识指令、结构体、枚举和函数定义.

SPDX许可标识
SPDX：The Software Package Data Exchange
常见开源：
// SPDX-License-Identifier: MIT
私有或者无授权：
// SPDX-License-Identifier: UNLICENSED
版本标识
pragma solidity ^0.8.4;或者 pragma solidity >=0.4.16 <0.9.0;
ABICoder Pragma
Solidity 0.7.4 之前：pragma experimental ABIEncoderV2
Solidity 0.7.4 之后：pragma abicoder v2

导入文件

import "filename";
示例：
import "./helper.sol";

注释

// This is a single-line comment./*
This is a
multi-line comment.
*/

2. 合约结构

状态变量

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.4.0 <0.9.0;contract SimpleStorage {uint storedData; // State variable// ...
}

函数

/ SPDX-License-Identifier: GPL-3.0
pragma solidity >0.7.0 <0.9.0;contract TinyAuction {function Mybid() public payable { // 定义函数// ...}
}// Helper function defined outside of a contract
function helper(uint x) pure returns (uint) {return x * 2;
}

函数修饰器

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.4.22 <0.9.0;contract Purchase {address public seller;modifier onlySeller() { // Modifierrequire(msg.sender == seller,"Only seller can call this.");_;}function abort() public view onlySeller { // Modifier usage// ...}
}

事件

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.4.21 <0.9.0;contract SimpleAuction {event HighestBidIncreased(address bidder, uint amount); // Eventfunction bid() public payable {// ...emit HighestBidIncreased(msg.sender, msg.value); // Triggering event}
}

异常处理

使用revert或者require(推荐)

// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.4;/// Not enough funds for transfer. Requested `requested`,
/// but only `available` available.
error NotEnoughFunds(uint requested, uint available);contract Token {mapping(address => uint) balances;function transfer(address to, uint amount) public {uint balance = balances[msg.sender];if (balance < amount)revert NotEnoughFunds(amount, balance);balances[msg.sender] -= amount;balances[to] += amount;// ...}function transfer2(address to, uint amount) public {uint balance = balances[msg.sender];require(balance > amount," balance must be greater than amount");balances[msg.sender] -= amount;balances[to] += amount;// ...}
}

结构

pragma solidity >=0.4.0 <0.9.0;contract Ballot {struct Voter { // 结构体uint weight;bool voted;address delegate;uint vote;}
}

枚举

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.4.25 <0.9.0;contract Purchase {enum State { Created, Locked } // Enum
}

3. 常用信息

数据类型

值类型：Booleans（true&false）、Integers(int8 to int256,uint8 to uint256)、Address（长度40位，20字节）、byte（byte1 to byte32)。
引用类型：struct、bytes(byte[])、string、mapping。
引用类型可以通过多个不同的名称修改它的值，而值类型的变量，每次都有独立的副本。因此，必须比值类型更谨慎地处理引用类型。目前，引用类型包括结构，数组和映射，如果使用引用类型，则必须明确指明数据存储哪种类型的位置（空间）里：
a. memory :数据在内存中，因此数据仅在其生命周期内（函数调用期间）有效。不能用于外部调用。
b. storage :状态变量保存的位置，只要合约存在就一直存储．
c. calldata:调用数据时用来保存函数参数的特殊数据位置，是一个只读位置，无需copy变量值到其他存储位置。
类型修饰符：私有（private）、内部（internal）、公共（public）、外部（external）；函数默认为internal，状态变量默认为private。另外函数还包含view（读取账本）和pure（不读取也不更改账本）。
详解:
private：仅内部访问。
internal: 仅内部以及派生类访问。
external：仅外部访问。
public：内部和外部都可以访问。

特殊变量和函数

abi.encode(...) returns (bytes)： ABI - 对给定参数进行编码
abi.encodePacked(...) returns (bytes)：对给定参数执行 紧打包编码
abi.encodeWithSelector(bytes4 selector, ...) returns (bytes)： ABI- 对给定参数进行编码，并以给定的函数选择器作为起始的 4 字节数据一起返回
abi.encodeWithSignature(string signature, ...) returns (bytes)：等价于 abi.encodeWithSelector(bytes4(keccak256(signature), ...)
block.blockhash(uint blockNumber) returns (bytes32)：指定区块的区块哈希——仅可用于最新的 256 个区块且不包括当前区块
block.chainid (uint): 当前链 id
block.coinbase ( address ): 挖出当前区块的矿工地址
block.difficulty ( uint ): 当前区块难度
block.gaslimit ( uint ): 当前区块 gas 限额
block.number ( uint ): 当前区块号
block.timestamp ( uint): 自 unix epoch 起始当前区块以秒计的时间戳
gasleft() returns (uint256) ：剩余的 gas
msg.data ( bytes ): 完整的 calldata
msg.sender ( address ): 消息发送者（当前调用）
msg.sig ( bytes4 ): calldata 的前 4 字节（也就是函数标识符）
msg.value ( uint ): 随消息发送的 wei 的数量
tx.gasprice (uint): 交易的 gas 价格
tx.origin (address payable): 交易发起者（完全的调用链）
address(this):当前合约的地址

内联汇编

通常我们通过库代码，来增强语言我，实现一些精细化的控制，Solidity为我们提供了一种接近于EVM底层的语言，内联汇编，允许与Solidity结合使用。由于EVM是栈式的，所以有时定位栈比较麻烦，Solidty的内联汇编为我们提供了下述的特性，来解决手写底层代码带来的各种问题：允许函数风格的操作码：mul(1, add(2, 3))等同于push1 3 push1 2 add push1 1 mul
内联局部变量：let x := add(2, 3) let y := mload(0x40) x := add(x, y)
可访问外部变量：function f(uint x) { assembly { x := sub(x, 1) } }
标签：let x := 10 repeat: x := sub(x, 1) jumpi(repeat, eq(x, 0))
循环：for { let i := 0 } lt(i, x) { i := add(i, 1) } { y := mul(2, y) }
switch语句：switch x case 0 { y := mul(x, 2) } default { y := 0 }
函数调用：function f(x) -> y { switch x case 0 { y := 1 } default { y := mul(x, f(sub(x, 1))) } }

pragma solidity ^0.4.0;library GetCode {function at(address _addr) returns (bytes o_code) {assembly {// retrieve the size of the code, this needs assemblylet size := extcodesize(_addr)// allocate output byte array - this could also be done without assembly// by using o_code = new bytes(size)o_code := mload(0x40)// new "memory end" including paddingmstore(0x40, add(o_code, and(add(add(size, 0x20), 0x1f), not(0x1f))))// store length in memorymstore(o_code, size)// actually retrieve the code, this needs assemblyextcodecopy(_addr, add(o_code, 0x20), 0, size)}}
}

合约

Solidity中合约有点类似面向对象语言中的类。合约中有用于数据持久化的状态变量(state variables)，和可以操作他们的函数。调用另一个合约实例的函数时，会执行一个EVM函数调用，这个操作会切换执行时的上下文，这样，前一个合约的状态变量(state variables)就不能访问了。

创建合约

合约可以通过Solidity，或不通过Solidity创建。当合约创建时，一个和合约同名的函数(构造器函数)会调用一次，用于初始化。
构造器函数是可选的。仅能有一个构造器，所以不支持重载。
如果不通过Solidity，我们可以通过web3.js，使用JavaScript的API来完成合约创建:

pragma solidity ^0.4.0;contract OwnedToken {// TokenCreator is a contract type that is defined below.// It is fine to reference it as long as it is not used// to create a new contract.TokenCreator creator;address owner;bytes32 name;// This is the constructor which registers the// creator and the assigned name.function OwnedToken(bytes32 _name) {// State variables are accessed via their name// and not via e.g. this.owner. This also applies// to functions and especially in the constructors,// you can only call them like that ("internall"),// because the contract itself does not exist yet.owner = msg.sender;// We do an explicit type conversion from `address`// to `TokenCreator` and assume that the type of// the calling contract is TokenCreator, there is// no real way to check that.creator = TokenCreator(msg.sender);name = _name;}function changeName(bytes32 newName) {// Only the creator can alter the name --// the comparison is possible since contracts// are implicitly convertible to addresses.if (msg.sender == address(creator))name = newName;}function transfer(address newOwner) {// Only the current owner can transfer the token.if (msg.sender != owner) return;// We also want to ask the creator if the transfer// is fine. Note that this calls a function of the// contract defined below. If the call fails (e.g.// due to out-of-gas), the execution here stops// immediately.if (creator.isTokenTransferOK(owner, newOwner))owner = newOwner;}
}contract TokenCreator {function createToken(bytes32 name)returns (OwnedToken tokenAddress){// Create a new Token contract and return its address.// From the JavaScript side, the return type is simply// "address", as this is the closest type available in// the ABI.return new OwnedToken(name);}function changeName(OwnedToken tokenAddress, bytes32 name) {// Again, the external type of "tokenAddress" is// simply "address".tokenAddress.changeName(name);}function isTokenTransferOK(address currentOwner,address newOwner) returns (bool ok) {// Check some arbitrary condition.address tokenAddress = msg.sender;return (keccak256(newOwner) & 0xff) == (bytes20(tokenAddress) & 0xff);}
}

库(Libraries)

库与合约类似，但它的目的是在一个指定的地址，且仅部署一次，然后通过EVM的特性DELEGATECALL(Homestead之前是用CALLCODE)来复用代码。这意味着库函数调用时，它的代码是在调用合约的上下文中执行。使用this将会指向到调用合约，而且可以访问调用合约的存储(storage)。因为一个合约是一个独立的代码块，它仅可以访问调用合约明确提供的状态变量(state variables)，否则除此之外，没有任何方法去知道这些状态变量。

使用库合约的合约，可以将库合约视为隐式的父合约(base contracts)，当然它们不会显式的出现在继承关系中。但调用库函数的方式非常类似，如库L有函数f()，使用L.f()即可访问。此外，internal的库函数对所有合约可见，如果把库想像成一个父合约就能说得通了。当然调用内部函数使用的是internal的调用惯例，这意味着所有internal类型可以传进去，memory类型则通过引用传递，而不是拷贝的方式。为了在EVM中实现这一点，internal的库函数的代码和从其中调用的所有函数将被拉取(pull into)到调用合约中，然后执行一个普通的JUMP来代替DELEGATECALL。

pragma solidity ^0.4.0;library Set {// We define a new struct datatype that will be used to// hold its data in the calling contract.struct Data { mapping(uint => bool) flags; }// Note that the first parameter is of type "storage// reference" and thus only its storage address and not// its contents is passed as part of the call.  This is a// special feature of library functions.  It is idiomatic// to call the first parameter 'self', if the function can// be seen as a method of that object.function insert(Data storage self, uint value)returns (bool){if (self.flags[value])return false; // already thereself.flags[value] = true;return true;}function remove(Data storage self, uint value)returns (bool){if (!self.flags[value])return false; // not thereself.flags[value] = false;return true;}function contains(Data storage self, uint value)returns (bool){return self.flags[value];}
}contract C {Set.Data knownValues;function register(uint value) {// The library functions can be called without a// specific instance of the library, since the// "instance" will be the current contract.if (!Set.insert(knownValues, value))throw;}// In this contract, we can also directly access knownValues.flags, if we want.
}

接口

/*接口与抽象合约类似，与之不同的是，接口内没有任何函数是已实现的，同时还有如下限制：
不能继承其它合约，或接口。
不能定义构造器
不能定义变量
不能定义结构体
不能定义枚举类*/
interface Token {function transfer(address recipient, uint amount);
}

抽象(Abstract Contracts)

pragma solidity ^0.4.0;contract Feline {function utterance() returns (bytes32);function getContractName() returns (string){return "Feline";}
}contract Cat is Feline {function utterance() returns (bytes32) { return "miaow"; }
}

4. 示例

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.4;// pragma experimental ABIEncoderV2;import "./helper.sol";/*** @title Storage* @dev Store & retrieve value in a variable*/
contract Storage {address public seller;constructor(){seller = msg.sender;}modifier onlySeller() { // Modifierrequire(msg.sender == seller,"Only seller can call this.");_;}uint256 number;event storeEvent(string name,uint256 value);/*** @dev Store value in variable* @param num value to store*/function store(uint256 num) public {number = num;emit storeEvent("number",number);}/*** @dev Return value * @return value of 'number'*/function retrieve() public view returns (uint256){return number;}// only call by sellerfunction storeOnlySeller(uint256 num) public onlySeller {// number = num;number = Helper.add(num,1);emit storeEvent("number",number);}// destory the contractfunction destory() public onlySeller {selfdestruct(payable(msg.sender));}}

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.4;library Helper {function add(uint256 a,uint256 b) public pure returns(uint256) {return (a+b);}}

5.合约编写

pragma solidity >=0.4.22 <0.5.0;//ERC20协议接口
contract ERC20Interface{function totalSupply() public constant returns(uint);function balanceOf(address tokenOwner) public constant returns(uint balance) ;function allowance(address tokenOwner,address spender) public constant returns(uint remainIng);function transfer(address to,uint tokens) public returns(bool success);function approve(address spender,uint tokens) public returns(bool success);function transferFrom(address from,address to,uint tokens) public returns(bool success);event Transfer(address indexed from,address indexed to, uint tokens);event Approval(address indexed tokenOwner,address indexed spender,uint tokens);}/*** @title SafeMath 安全计算，避免溢出* @dev Math operations with safety checks that throw on error*/
library SafeMath {/*** @dev Multiplies two numbers, throws on overflow.*/function mul(uint256 a, uint256 b) internal pure returns (uint256) {if (a == 0) {return 0;}uint256 c = a * b;assert(c / a == b);return c;}/*** @dev Integer division of two numbers, truncating the quotient.*/function div(uint256 a, uint256 b) internal pure returns (uint256) {// assert(b > 0); // Solidity automatically throws when dividing by 0uint256 c = a / b;// assert(a == b * c + a % b); // There is no case in which this doesn't holdreturn c;}/*** @dev Substracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).*/function sub(uint256 a, uint256 b) internal pure returns (uint256) {assert(b <= a);return a - b;}/*** @dev Adds two numbers, throws on overflow.*/function add(uint256 a, uint256 b) internal pure returns (uint256) {uint256 c = a + b;assert(c >= a);return c;}
}/*** @title Ownable 权限控制* @dev The Ownable contract has an owner address, and provides basic authorization control* functions, this simplifies the implementation of "user permissions".*/
contract Ownable {address public owner;//这里是个事件，供前端监听event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);/*** @dev The Ownable constructor sets the original `owner` of the contract to the sender* account.这是一个构造函数，在合约启动时只运行一次，将合约的地址赋给地址owner*/function Ownable() public {owner = msg.sender;}/*** @dev Throws if called by any account other than the owner。这里就是modifier onlyOwner的修饰符，用来判定是否是合约的发布者* 修饰器，通常用于校验函数权限只有合约的拥有者才能执行函数*/modifier onlyOwner() {require(msg.sender == owner);_;}/*** @dev Allows the current owner to transfer control of the contract to a newOwner.* @param newOwner The address to transfer ownership to.* 让合约拥有者修改指定新的合约拥有者，并调用事件来监听*/function transferOwnership(address newOwner) public onlyOwner {require(newOwner != address(0));OwnershipTransferred(owner, newOwner);owner = newOwner;}}contract bmtToken is ERC20Interface , Ownable{using SafeMath for uint;//代币名称string public name;//代币符号 ，比如 BTCstring public symbol;//代币精度，比如 ETC 有18位uint8 public decimals;//发行总额uint public totalSupply;//地址 => 余额 映射关系mapping(address => uint) balances;//授权 地址A 授权给 地址B  多少个代币mapping(address => mapping(address => uint)) allowed;constructor() public {name = "BMT Token";symbol = "BMT";decimals = 18;totalSupply = 1000000000000000000;balances[msg.sender] = totalSupply;Transfer(address(0),msg.sender,totalSupply);}function totalSupply() public constant returns(uint){return totalSupply;}//获取账户余额function balanceOf(address tokenOwner) public constant returns(uint){return balances[tokenOwner];}//转账给地址tofunction transfer(address to, uint tokens) public returns (bool){balances[msg.sender] = balances[msg.sender].sub(tokens);balances[to] = balances[to].add(tokens);//触发事件Transfer(msg.sender,to,tokens);return true;}//被授权账户余额function allowance (address tokenOwner,address spender) public constant returns(uint){return allowed[tokenOwner][spender];}//授权给账户address tokens个代币function approve(address spender,uint tokens) public returns(bool){allowed[msg.sender][spender] = tokens;//触发事件Approval(msg.sender,spender,tokens);return true;}//from 转账给 to function transferFrom(address from,address to,uint tokens) public returns(bool){allowed[from][to] = allowed[from][to].sub(tokens);balances[from] = balances[from].sub(tokens);balances[to] = balances[to].add(tokens);//触发事件Transfer(from,to,tokens);return true;}//niming匿名 huigun回滚 hanshu函数function () payable{//hanshu函数buneng不能 zhixing执行，hui会 huigun回滚 revert();}//合约 与 合约 之间交互，代币 与 代币 交易 function transferAnyERC20Token(address tokenAddr,uint tokens)public onlyOwner returns(bool) {//nenggou能够 jieshou接收接收renhe接收 shix实现ERCjiekou接口 d的 daibi代币 zhuangzhang转账 ERC20Interface(tokenAddr).transfer(msg.sender,tokens);}}

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solidity开发讲解

solidity 教程链接

1. 源文件结构

源文件中可以包含任意多个合约定义、导入源文件指令、版本标识指令、结构体、枚举和函数定义.

导入文件

注释

2. 合约结构

3. 常用信息

数据类型

特殊变量和函数

内联汇编

合约

创建合约

库(Libraries)

接口

抽象(Abstract Contracts)

4. 示例

5.合约编写

solidity开发讲解相关推荐

最新文章

热门文章

solidity开发讲解

solidity 教程链接

1. 源文件结构

源文件中可以包含任意多个 合约定义 、导入源文件指令 、 版本标识 指令、 结构体 、 枚举 和 函数 定义.

导入文件

注释

2. 合约结构

3. 常用信息

数据类型

特殊变量和函数

内联汇编

合约

创建合约

库(Libraries)

接口

抽象(Abstract Contracts)

4. 示例

5.合约编写

solidity开发讲解相关推荐

最新文章

热门文章

源文件中可以包含任意多个合约定义、导入源文件指令、版本标识指令、结构体、枚举和函数定义.