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39- Expert Q&A
May 24, 2025project security using blockchain
hi guys,I recently started as a intern in a startup as a blockchain developer for security part of the project and right now I'm doing cyfrin smart contract security and auditing course, i need your suggestionsfor what and how to provide security which we are deploying in the cloud .
- Smart Contract
- Solidity
01 - Expert Q&AMar 29, 2025
How to generate random Number between 1&2 without VRF?
So I was making a coinflip game which assigns head- 1 and tails -2 and when user places bet on polygon chain.... smart contract generates a random number between 1 and 2 and if the outcome is same...user gets double - (5 % as fee to the owner of contract) ! from a pool and if outcome is different then user loses all and the lost amount is deposited in the pool - (3% as fee to the owner) (to fund winners)... but any way to make genrate a random number? I have no funds at all so I can't afford chainlink VRF to generate. So is there any other secure way for this? plus I am pritty new to solidity so I made this code with help of chat gpt but I don't it works....can anyone help to make the code better? code- // SPDX-License-Identifier: MIT pragma solidity ^0.8.0; contract CoinFlip { address public owner; uint256 public contractBalance; event BetPlaced(address indexed player, uint256 amount, bool choice); event BetResult(address indexed player, uint256 amount, bool won); constructor() { owner = msg.sender; } function placeBet(bool choice) external payable { require(msg.value > 0, "Bet amount must be greater than 0"); bool outcome = (block.timestamp % 2 == 0); // Simple pseudo-random outcome if (outcome == choice) { uint256 winAmount = (msg.value * 2 * 95) / 100; require(address(this).balance >= winAmount, "Insufficient contract balance"); payable(msg.sender).transfer(winAmount); emit BetResult(msg.sender, winAmount, true); } else { uint256 lostAmount = (msg.value * 97) / 100; contractBalance += lostAmount; emit BetResult(msg.sender, msg.value, false); } emit BetPlaced(msg.sender, msg.value, choice); } function depositFunds() external payable { require(msg.sender == owner, "Only owner can deposit funds"); contractBalance += msg.value; } function withdrawFunds(uint256 amount) external { require(msg.sender == owner, "Only owner can withdraw funds"); require(amount <= address(this).balance, "Insufficient contract balance"); payable(owner).transfer(amount); contractBalance -= amount; } } `
- Smart Contract
- Solidity
01 - DiscussionFeb 27, 2025
smart contract auditing journey
what advice will you give someone just starting the smart contract auditing journey
- Smart Contract
- Solidity
- Yul
01 - DiscussionFeb 24, 2025
Hey guys, Im new here. I was hoping anyone could give me links to learn solidity effectively.
//SDPX Licence Identifier: MIT pragma solidity 0.8.24; contract Hello World { string public Hello World; } //Just had to add something here
- Smart Contract
- Solidity
03 - DiscussionDec 09, 2024
Beginner to Solidity
After taking the beginner course on cyfrin updraft, i am trying to build something so i can cement the knowledge, but it's as if i know nothing. Really making me sad. What advice will you guys give
- Smart Contract
- Solidity
23Best Answer - DiscussionSep 13, 2024
Seeking Freelance Opportunities for Beginner Solidity Developer"
I have been studying Solidity for a couple of weeks and do not have any previous IT background. Are there any opportunities for me to get freelance work or earn money with my current skills?
- Solidity
- Use cases
00 - DiscussionJul 24, 2024
Formatting/Hello
I am new to Solidity! I wanted to say hello to this awesome community in hopes that it will get me out of my shell, and hopefully meet new people. I have zero programming experience, but love crypto. When posting questions in these forums is there a certain format I should post my question in, and/or any not so obvious rules I should follow in these forums? Thank you for taking the time to read, and leaving a reply!
- Smart Contract
- Solidity
- Use cases
01 - DiscussionJul 13, 2024
Career Path in WEB3 Auditing: Project Building or Learning Auditing First?
Hi everyone, I've recently completed the Solidity and Foundry basic and advanced courses with Cyfrin Updraft. I'm contemplating my next steps and considering a career in Solidity. Should I start learning smart contract auditing at this stage, or would it be more beneficial to first create some projects to solidify my current knowledge? Looking forward to your advice!
- Smart Contract
- Solidity
01 - Expert Q&AJun 04, 2024
How often does the solidity syntax change
I'd like to know how often the solidity syntax rules are changed and the best newsletter to follow up on the most recent updates
- Smart Contract
- Solidity
- Language Grammar
- Solidity Compiler
11 - DiscussionMay 31, 2024
Reentrancy Vulnerability
Hello everyone , I've noticed that the offer function uses the .call{value: amount}("") method to send Ether to the recipient's address. Could anyone provide insight into whether this function is indeed vulnerable to reentrancy and suggest any best practices or modifications to mitigate such risks? function _offer(address to, uint256 amount) internal { balance -= amount; (bool success, ) = to.call{value: amount}(""); if (!success) { revert TransferFailed(address(0), address(this), to, amount); } } `
- Smart Contract
- Solidity
- Solidity Compiler
01
Solidity is an object-oriented, high-level language for implementing smart contracts. It is a curly-bracket language designed to target the Ethereum Virtual Machine (EVM).
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