cxk228922.md

timezone
Asia/Taipei

---

Robin

1. 自我介绍
   大家好我是Robin(cxk228922)，一名正在台灣就讀高二的學生，對資訊安全頗有興趣
   之前都是往計算機本身漏洞探究，想慢慢跨進到網路相關的內容。
2. 你认为你会完成本次残酷学习吗？
   我會盡我所能完成一切

Notes

這邊先和助教說聲抱歉，由於我最近課業繁忙，並且對網路、區塊鏈並沒有基礎，每天能學習的內容有限><。以及我想趁此機會練習英文，文法可能有許多不妥處，可能有點難以閱讀。

2024.09.23

1. Remix IDE

• File Extension of Solidity : .sol
• Ctrl + S -> Compile
• Deploy -> Simulate Ethereum chain -> run smart contracts

2. Basic

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.21;
contract HelloWeb3{
    string public _string = "Hello Web3!";
}

• // SPDX-License-Identifier: MIT -> Denotes license identifier (MIT for example)
• pragma solidity ^0.8.21; -> Only allow compiler version 0.8.21 ~ 0.9.0(0.8.21 for example)
• contract HelloWeb3 -> Similar as class in other programming language (HelloWeb3 for example). also,we call it "合約"
• string public _string = "Hello Web3!"; -> Declared Variables
• string : Value type

Type	Explain	Example
int	integer	3 , 300 , -123
uint	unsigned integer(include 0)	3 , 300
uint	k-bit unsigned integer	uint8 , uint64
bool	boolean	true , false
address	address(e.g. ETH account)	0x1234556
enum	enumeration	{Mon=1,Tue,Wed}

• public : visibility

Type	Outside Contract	In Contract	Inheritance Contract
public	✅	✅	✅
private	❌	✅	❌
external (function)	✅	✅use this.func()	✅use this.func()
internal	❌	✅	✅

• _string : Value name,Define by your self
• "Hello Web3!" : Value

---

function <functionName>(<Type> <ParameterName>) <visibility> <modifier> returns (<Type>) 

<Type> <parameter1> : Input parameter,e.g. int a      Also,you can input more than 1 parameter

<modifier> :

Value	Explain
pure	cannot read nor write
view	can read but cannot write
(NULL)	can both read and write
payable	can receive ETH

2024.09.24

1. Variables

data storage locations:

Type	stored	modified
storage(deafult)	on-chain	✅
memory	in memory	✅
calldata	in memory	❌(read-only)

scope:

contract Example {
    uint public count;
    function increment() public pure returns (uint) {
        uint localCount = 0; 
        return localCount;
    }
}

Type	Location	Complain/Example
State(狀態變量)	storage	count(in contract storage)
Local(局部變量)	memory(reference types) stack(basic types)	localCount(in function)
Global(全局變量)	EVM dynamic	msg.sender,block.number

2. Array

//fixed-sized arrays
<type>[<length>] <name>;
<type>[] memory <name> = new <type>[](<length>);
uint[9] array;
uint[] memory array3 = new uint[](5);

//dynamic-sized array
uint[] array1;
bytes array2;    //dynamic byte array

• .length -> return array's length dynamic array :
• .push -> add 0element at the end of array
• .puxh(x) -> add xelement at the end of array
• .pop -> remove the last element of array

3. Struct

struct Student{
    uint id;
    uint score; 
}
//4 ways to assign value
function method1() external{
    Student storage _student = student; //copy Student
    _student.id = 11;
    _student.score = 100;
}
function method2() external{
    student.id = 1;
    student.score = 80;
}
function method3() external {
    student = Student(3, 90);
}
function method4() external {
    student = Student({id: 4, score: 60});
}

4. Map key -> Value

mapping(<KeyType> => <ValueType>) public <name>;
mapping(address => uint) public balances;

<name>[<key>] = <Value>;
balances[msg.sender] = 100;

2024.09.25

1. constant/immutable

Characteristic	constant	immutable
Initialization time	declaration	constructor/declaration
Modification time	Compile-time constant	Determined at deployment
Storage location	Inlined directly at compile-time	storage
Use cases	completely fixed values (e.g. fixed rates)	values determined by conditions at deployment time (e.g.deployer)

2. Control flow
   as same as C

//if-else
function ifElseTest(uint256 _number) public pure returns(bool){
    if(_number == 0){
        return(true);
    }else{
        return(false);
    }
}
//for loop
function forLoopTest() public pure returns(uint256){
    uint sum = 0;
    for(uint i = 0; i < 10; i++){
        sum += i;
    }
    return(sum);
}
//while
function doWhileTest() public pure returns(uint256){
    uint sum = 0;
    uint i = 0;
    do{
        sum += i;
        i++;
    }while(i < 10);
    return(sum);
}
//Insertion Sort
function insertionSort(uint[] memory a) public pure returns(uint[] memory) {
    for (uint i = 1;i < a.length;i++){
        uint temp = a[i];
        //uint j=i-1;
        uint j=i;    //uint can't <0
        while( (j >= 1) && (temp < a[j-1])){    
        //before:(temp < a[j])
            a[j] = a[j-1];
            j--;
        }
        a[j] = temp;
    }
    return(a);
}