additional practice

alpha.sol

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+//SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.13;
+
+contract alpha{
+
+    mapping(uint => string) public counter;
+
+    constructor(){
+        counter[1] = "A";
+        counter[2] = "B";
+        counter[3] = "C";
+        counter[4] = "D";
+        counter[5] = "E";
+        counter[6] = "F";
+        counter[7] = "G";
+        counter[8] = "H";
+        counter[9] = "I";
+        counter[10] = "J";
+        counter[11] = "K";
+        counter[12] = "L";
+        counter[13] = "M";
+        counter[14] = "N";
+        counter[15] = "O";
+        counter[16] = "P";
+        counter[17] = "Q";
+        counter[18] = "R";
+        counter[19] = "S";
+        counter[20] = "T";
+        counter[21] = "U";
+        counter[22] = "V";
+        counter[23] = "W";
+        counter[24] = "X";
+        counter[25] = "Y";
+        counter[26] = "Z";
+    }
+
+
+
+    function turnToAlpha(uint[] memory numbers) public view returns(string memory){
+
+        string memory finalWord = "";
+        for(uint i=0;i<numbers.length;i++){
+            finalWord = string.concat(finalWord, counter[numbers[i]]);
+        }
+        return finalWord;
+
+    }
+
+}

events.sol

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+//SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.13;
+
+contract events{
+
+    event log1(uint a, address ad, string text);
+    event log2(uint indexed a, address ad, string text);
+    event log3(uint a, address ad, string indexed text);
+
+    function callLog1() public{
+        emit log1(5, 0x5B38Da6a701c568545dCfcB03FcB875f56beddC4, "test" );
+    }
+
+    function callLog2() public{
+        emit log2(5, 0x5B38Da6a701c568545dCfcB03FcB875f56beddC4, "test" );
+    }
+
+    function callLog3() public{
+        emit log3(5, 0x5B38Da6a701c568545dCfcB03FcB875f56beddC4, "test" );
+    }
+}

multiSign.sol

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+//SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.13;
+
+contract multiSign{
+
+    address[] public owners;
+    mapping(address => bool) public ownerList;
+    mapping(uint => mapping(address => bool)) public alreadyVoted;
+    uint public approvalsNeeded;
+
+    struct transaction{
+        address sendTo;
+        uint amount;
+        uint approvals;
+        bool execution;
+    }
+
+    transaction[] public proposedTransactions;
+
+    constructor(){
+        ownerList[msg.sender] = true;
+        owners.push(msg.sender);
+    }
+
+    receive() external payable{}
+
+    modifier onlyOwner{
+        require(ownerList[msg.sender] == true, "Only owner is allowed");
+        _;
+    }
+
+    function setApprovalsNeeded(uint need) public {
+        approvalsNeeded = need;
+    }
+
+    function addOwner(address newOwner) onlyOwner public {
+        owners.push(newOwner);
+        ownerList[newOwner] = true;
+    }
+
+    function proposeTransaction(address to, uint value) public {
+        proposedTransactions.push(transaction({
+            sendTo: to,
+            amount: value,
+            approvals: 0,
+            execution: false
+        }));
+
+    }
+
+    function voteTransaction(uint index) onlyOwner public {
+        require(alreadyVoted[index][msg.sender]==false, "Already voted");
+        proposedTransactions[index].approvals += 1;
+        alreadyVoted[index][msg.sender] = true;
+    }
+
+    function revokeVote(uint index) onlyOwner public {
+        require(alreadyVoted[index][msg.sender]==true, "No Previous vote found to revoke");
+        proposedTransactions[index].approvals -= 1;
+        alreadyVoted[index][msg.sender] = false;
+    }
+
+    function executeTx(uint index) onlyOwner public{
+        require(proposedTransactions[index].approvals >= approvalsNeeded,"No enough approvals");
+        require(proposedTransactions[index].execution==false, "Already executed");
+
+        address payable sender = payable(proposedTransactions[index].sendTo);
+        (bool tryToSend,) = sender.call{value: proposedTransactions[index].amount, gas: 5000}("");
+        require(tryToSend== true,"No enough ETH balance");
+        proposedTransactions[index].execution = true;
+
+    }
+
+}
+