# Alchemy University 学习教程，Smart Contract Basics

**Published by:** [冰糖vs橙子](https://paragraph.com/@bible666/)
**Published on:** 2023-01-08
**URL:** https://paragraph.com/@bible666/alchemy-university-smart-contract-basics

## Content

估值102亿融资5.45亿的Alchemy 项目，大学每周任务逐步开始。持有大学生早期卡的伙伴们可以开始大学生活了： 官方大佬的 lens ，可以关注下： https://lenster.xyz/u/vitto.lens 了解更多，请关注作者：https://twitter.com/bitc2024 这一期学习Smart Contract Basics： Solidity Syntax Data Types 1: Booleans 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { bool public a = true; bool public b = false; } 点击运行。 2: Unsigned Integers 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { uint8 public a = 3; uint16 public b = 268; uint256 public sum = a + b; } 点击运行。 3: Signed Integers 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { int8 public a = 10; int8 public b = -15; int16 public difference = a - b; } 点击运行。 4: String Literals 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { bytes32 public msg1 = "Hello World"; string public msg2 = "ccccccccccccccccccccccccccccccccabcd"; } 点击运行。 5: Enum 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { enum Foods { Apple, Pizza, Bagel, Banana } Foods public food1 = Foods.Apple; Foods public food2 = Foods.Pizza; Foods public food3 = Foods.Bagel; Foods public food4 = Foods.Banana; } 点击运行。 Functions Functions 1: Arguments 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { uint public x; constructor(uint _x) { x = _x; } } 点击运行。 2: Increment 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { uint public x; constructor(uint _x) { x = _x; } function increment() external { x = x + 1; } } 点击运行。 3: View Addition 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { uint public x; constructor(uint _x) { x = _x; } function increment() external { x = x + 1; } function add(uint _x) external view returns(uint) { uint sum = x + _x; return sum; } } 点击运行。 4: Pure Double 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { function double(uint x) external pure returns(uint d) { d = x * 2; } } 点击运行。 5: Double Overload 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { function double(uint x) external pure returns(uint d) { d = x * 2; } function double(uint x, uint y) public pure returns(uint, uint) { return (x*2, y*2); } } 点击运行。 Smart Contract Communication Contracts with ethers.js 1: Getter 查看要求： 输入： /** * Find the `value` stored in the contract * * @param {ethers.Contract} contract - ethers.js contract instance * @return {promise} a promise which resolves with the `value` */ function getValue(contract) { let value = contract.value(); return value; } module.exports = getValue; 点击运行。 2: Setter 查看要求： 输入： /** * Modify the `value` stored in the contract * * @param {ethers.Contract} contract - ethers.js contract instance * @return {promise} a promise of transaction */ function setValue(contract) { return contract.modify(6); } module.exports = setValue; 点击运行。 3: Transfer 查看要求： 输入： /** * Transfer funds on the contract from the current signer * to the friends address * * @param {ethers.Contract} contract - ethers.js contract instance * @param {string} friend - a string containing a hexadecimal ethereum address * @return {promise} a promise of the transfer transaction */ function transfer(contract, friend) { return contract.transfer(friend, 1000); } module.exports = transfer; 点击运行。 4: Signer 查看要求： 输入： /** * Set the message on the contract using the signer passed in * * @param {ethers.Contract} contract - ethers.js contract instance * @param {ethers.types.Signer} signer - ethers.js signer instance * @return {promise} a promise of transaction modifying the `message` */ function setMessage(contract, signer) { return contract.connect(signer).modify("abc"); } module.exports = setMessage; 点击运行。 5: Deposit 查看要求： 输入： const ethers = require('ethers'); /** * Deposit at least 1 ether into the contract * * @param {ethers.Contract} contract - ethers.js contract instance * @return {promise} a promise of the deposit transaction */ function deposit(contract) { return contract.deposit({ value: ethers.utils.parseEther("3")}); } module.exports = deposit; 点击运行。 Address Interactions Sending Ether 1: Storing Owner 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { address public owner; constructor() { owner = msg.sender; } } 点击运行。 2: Receive Ether 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { address public owner; constructor() { owner = msg.sender; } receive() external payable { } } 点击运行。 3: Tip Owner 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { address public owner; constructor() { owner = msg.sender; } receive() external payable { } function tip() public payable { (bool ret, ) = owner.call{ value: msg.value }(""); require(ret); } } 点击运行。 4: Charity 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { address public owner; address public charity; constructor(address _charity) { owner = msg.sender; charity = _charity; } receive() external payable { } function tip() public payable { (bool ret, ) = owner.call{ value: msg.value }(""); require(ret); } function donate() public { (bool ret, ) = charity.call{ value: address(this).balance }(""); require(ret); selfdestruct(payable(msg.sender)); } } 点击运行。 5: Self Destruct 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { address public owner; address public charity; constructor(address _charity) { owner = msg.sender; charity = _charity; } receive() external payable { } function tip() public payable { (bool ret, ) = owner.call{ value: msg.value }(""); require(ret); } function donate() public { (bool ret, ) = charity.call{ value: address(this).balance }(""); require(ret); selfdestruct(payable(msg.sender)); } } 点击运行。 Learning Revert 1: Constructor Revert 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { address deployer; constructor() payable { require(msg.value >= 1000000000000000000); deployer = msg.sender; } function withdraw() public { (bool ret, ) = deployer.call{ value: address(this).balance }(""); require(ret); } } 点击运行。 2: Only Owner 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { address deployer; constructor() payable { require(msg.value >= 1000000000000000000); deployer = msg.sender; } function withdraw() public { require(deployer == msg.sender); (bool ret, ) = deployer.call{ value: address(this).balance }(""); require(ret); } } 点击运行。 3: Owner Modifier 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.7.5; contract Contract { address owner; uint configA; uint configB; uint configC; constructor() { owner = msg.sender; } function setA(uint _configA) public onlyOwner { configA = _configA; } function setB(uint _configB) public onlyOwner { configB = _configB; } function setC(uint _configC) public onlyOwner { configC = _configC; } modifier onlyOwner { require(owner == msg.sender); _; } } 点击运行。 Sending Data 1: Call Function 查看要求： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; interface IHero { function alert() external; } contract Sidekick { function sendAlert(address hero) external { IHero(hero).alert(); } } 点击运行。 2: Signature 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Sidekick { function sendAlert(address hero) external { bytes4 signature = bytes4(keccak256("alert()")); (bool ret, ) = hero.call(abi.encodePacked(signature)); require(ret); } } 点击运行。 3: With Signature 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Sidekick { function sendAlert(address hero, uint enemies, bool armed) external { (bool ret, ) = hero.call( abi.encodeWithSignature("alert(uint256,bool)", enemies, armed) ); require(ret); } } 点击运行。 4: Arbitrary Alert 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Sidekick { function relay(address hero, bytes memory data) external { (bool ret, ) = hero.call(data); require(ret); } } 点击运行。 5: Fallback 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Sidekick { function makeContact(address hero) external { (bool ret, ) = hero.call(abi.encodeWithSignature("fallback()")); require(ret); } } 点击运行。 Practice Solidity Sum and Average 1: Sum and Average 查看要求： 输入： pragma solidity ^0.8.4; contract Contract { function sumAndAverage(uint a, uint b, uint c, uint d) external pure returns(uint,uint) { uint sum = a + b + c + d; uint average = sum / 4; return (sum, average); } } 点击运行。 Countdown 1: Countdown 查看要求： 输入： // SPDX-License-Identifier: MIT pragma solidity ^0.8.4; contract Contract { uint countdown = 10; function tick() external { countdown--; if (0 == countdown) { selfdestruct(payable(msg.sender)); } } } 点击运行。 以上，Smart Contract Basics，课程学习完成。 未完待续…… 了解更多，请关注作者：https://twitter.com/bitc2024 https://mirror.xyz/bible666.eth/X3VB59DNaNU37nTwsKOFwEUPZvEtuzbM0GJlMkK8x40

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