Update Jackchou.md

WTF solidity 101 ,1-4

Jackchou.md

@@ -51,43 +51,40 @@ timezone: Australia/Sydney # 澳大利亚东部标准时间 (UTC+10)
 ### 2024.09.23
 
 學習內容: 
-- A 系列的 Ethernaut CTF, 之前做了差不多了. POC: [ethernaut-foundry-solutions](https://github.com/SunWeb3Sec/ethernaut-foundry-solutions)
-- A 系列的 QuillAudit CTF 題目的網站關掉了, 幫大家收集了[題目](./Writeup/SunSec/src/QuillCTF/), 不過還是有幾題沒找到. 有找到題目的人可以在發出來.
-- A 系列的 DamnVulnerableDeFi 有持續更新, 題目也不錯. [Damn Vulnerable DeFi](https://github.com/theredguild/damn-vulnerable-defi/tree/v4.0.0).
-- 使用 [Foundry](https://book.getfoundry.sh/) 在本地解題目, 可以參考下面 RoadClosed 為例子
-- ``forge test --match-teat testRoadClosedExploit -vvvv``
-#### [QuillAudit CTF - RoadClosed](./Writeup/SunSec/src/QuillCTF/RoadClosed.sol)
-```
-  function addToWhitelist(address addr) public {
-    require(!isContract(addr), "Contracts are not allowed");
-    whitelistedMinters[addr] = true;
-  }
-
-  function changeOwner(address addr) public {
-    require(whitelistedMinters[addr], "You are not whitelisted");
-    require(msg.sender == addr, "address must be msg.sender");
-    require(addr != address(0), "Zero address");
-    owner = addr;
-  }
-
-  function pwn(address addr) external payable {
-    require(!isContract(msg.sender), " Contracts are not allowed");
-    require(msg.sender == addr, "address must be msg.sender");
-    require(msg.sender == owner, "Must be owner");
-    hacked = true;
-  }
-
-  function pwn() external payable {
-    require(msg.sender == pwner);
-    hacked = true;
-  }
-```
-- 解決這個題目需要成為合約的 owner 和 hacked = true.
-- On-chain: 可以透過 ``cast send`` 或是 forge script 來解.
-- Local: 透過 forge test 通常是在local解題, 方便 debug.
-- RoadClosed 為例子我寫了2個解題方式. testRoadClosedExploit 和 testRoadClosedContractExploit (因為題目有檢查msg.sender是不是合約, 所以可以透過constructor來繞過 isContract)
-- [POC](./Writeup/SunSec/test/QuillCTF/RoadClosed.t.sol) 
-
+- For this week, I will target on finishing solidity 101
+- Finished solidity 101, 1-4
+  - 3.function
+    ```
+    // SPDX-License-Identifier: MIT
+    pragma solidity ^0.8.4;
+    contract Quiz3{
+        // complete following funciton, let it return the sum of x and y
+        function sum(uint x, uint y) pure external returns (uint sumXY){
+            sumXY = x+y;
+        }
+    }
+    ```
+    output
+    ```
+    decoded input	{
+      "uint256 x": "2",
+      "uint256 y": "3"
+    }
+    decoded output	{
+      "0": "uint256: sumXY 5"
+    }
+    ```
+    - In Solidity, functions can be marked as `pure`, `view`, or `payable` to indicate their behavior. `pure` functions do not modify the contract's state, while `view` functions can read the state but not modify it. `payable` functions can receive Ether.
+  - 4.function Output 
+    - There are two keywords related to function output: return and returns:
+    ```
+    returns is added after the function name to declare variable type and variable name;
+    return is used in the function body and returns desired variables.
+        // returning multiple variables
+        function returnMultiple() public pure returns(uint256, bool, uint256[3] memory){
+                return(1, true, [uint256(1),2,5]);
+            }
+    ```
 ### 
 
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