evm-puzzles
A collection of EVM puzzles (by fvictorio)
openzeppelin-solidity
OpenZeppelin Contracts is a library for secure smart contract development. [Moved to: https://github.com/OpenZeppelin/openzeppelin-contracts] (by OpenZeppelin)
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evm-puzzles | openzeppelin-solidity | |
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5 | 4 | |
786 | 10,805 | |
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2.1 | 9.4 | |
9 months ago | almost 3 years ago | |
JavaScript | JavaScript | |
- | MIT License |
The number of mentions indicates the total number of mentions that we've tracked plus the number of user suggested alternatives.
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
evm-puzzles
Posts with mentions or reviews of evm-puzzles.
We have used some of these posts to build our list of alternatives
and similar projects. The last one was on 2022-03-24.
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More EVM Puzzles - Walkthrough
More EVM Puzzles are a collection of puzzles, similar to EVM Puzzles by Franco Victorio. In each puzzle, the objective is to have the code STOP, rather than REVERT.
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deep understanding?
Try these puzzles! If you can solve them all, you will be in a solid place for evm skills https://github.com/fvictorio/evm-puzzles
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EVM Puzzles - Walkthrough
EVM Puzzles are a collection of puzzles by Franco Victorio. In this Markdown file, I wrote down the walkthrough for each of them.
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I love backend and I hate frontend. As a backend blockchain dev, what can I do? I heard about Reentrancy today and I believe it’s a good way to work. But how to make money using Reentrancy?
I understand reentrancy. These vulnerabilities are rare today as they are very simple. You'll want a lot of experience developing complex smart contracts and learning EVM internals. Try solving these puzzles - once you can solve them confidently, you will be in a good spot on your fundamentals! https://github.com/fvictorio/evm-puzzles
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An awesome list of blockchain security-related Capture the Flag (CTF) competitions
EVM Puzzles
openzeppelin-solidity
Posts with mentions or reviews of openzeppelin-solidity.
We have used some of these posts to build our list of alternatives
and similar projects. The last one was on 2021-07-09.
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Attack Vectors in Solidity #6:Unexpected Ether( Incorrect Use of this.balance)
pragma solidity ^0.5.0; import "https://github.com/OpenZeppelin/openzeppelin-solidity/contracts/math/SafeMath.sol"; contract MyContract { using SafeMath for uint256; function deposit() public payable { // code to deposit ether } function withdraw(uint256 _amount) public { require(this.balance.sub(_amount) >= 0, "Insufficient funds"); // code to withdraw ether } }
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How to check if tokenholder is holding 2 different tokens at the same time before an event is triggered?
The basic structure could be done as follows using OZ ERC20 interface https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/token/ERC20/IERC20.sol
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Is this why shib price keeps going down?
return c; } /** * @dev Returns the subtraction of two unsigned integers, reverting on * overflow (when the result is negative). * * Counterpart to Solidity's `-` operator. * * Requirements: * - Subtraction cannot overflow. */ function sub(uint256 a, uint256 b) internal pure returns (uint256) { require(b <= a, "SafeMath: subtraction overflow"); uint256 c = a - b; return c; } /** * @dev Returns the multiplication of two unsigned integers, reverting on * overflow. * * Counterpart to Solidity's `*` operator. * * Requirements: * - Multiplication cannot overflow. */ function mul(uint256 a, uint256 b) internal pure returns (uint256) { // Gas optimization: this is cheaper than requiring 'a' not being zero, but the // benefit is lost if 'b' is also tested. // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522 if (a == 0) { return 0; } uint256 c = a * b; require(c / a == b, "SafeMath: multiplication overflow"); return c; } /** * @dev Returns the integer division of two unsigned integers. Reverts on * division by zero. The result is rounded towards zero. * * Counterpart to Solidity's `/` operator. Note: this function uses a * `revert` opcode (which leaves remaining gas untouched) while Solidity * uses an invalid opcode to revert (consuming all remaining gas). * * Requirements: * - The divisor cannot be zero. */ function div(uint256 a, uint256 b) internal pure returns (uint256) { // Solidity only automatically asserts when dividing by 0 require(b > 0, "SafeMath: division by zero"); uint256 c = a / b; // assert(a == b * c + a % b); // There is no case in which this doesn't hold return c; } /** * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo), * Reverts when dividing by zero. * * Counterpart to Solidity's `%` operator. This function uses a `revert` * opcode (which leaves remaining gas untouched) while Solidity uses an * invalid opcode to revert (consuming all remaining gas). * * Requirements: * - The divisor cannot be zero. */ function mod(uint256 a, uint256 b) internal pure returns (uint256) { require(b != 0, "SafeMath: modulo by zero"); return a % b; }
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can someone tell me what this contract wants?
// See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522