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pragma solidity ^0.4.24; contract ModifierTest { address public owner; struct myStruct { uint256 fancyVar; } constructor() public { owner = msg.sender; } modifier …

Unfortunately, as of the latest version of Solidity (0.4.24) and the EVM, this is not possible. The transaction is reverted and that's it. …

There's a mistake in your code. You never pass the address of msg.sender to an interface constructor. The solution to always interact with USDT is to store its address as a constant. address public co …

How to read only some variables from a tuple returned by a function in Solidity? …

Just use commas: /* SPDX-License-Identifier: LGPL-3.0-or-later */ pragma solidity ^0.7.1; contract TupleTest { function foo() public pure returns (uint256 left, uint256 middle, uint256 right) …

You can use the Solidity built-in function abi.decode for this. …

Does someone have a ready-to-use regex for Solidity pragmas? I need to perform certain actions based on what pragma the user wishes to use. (I'm writing a utility for Foundry.) …

As per the Solidity documentation: Interfaces are similar to abstract contracts, but they cannot have any functions implemented. There are further restrictions: ... … MyContract is MyInterface { function foo(bytes memory b) public view returns (bool) { ... } } Note: there are two additional parameters, virtual and override, to be cognizant of if you're using Solidity …

A struct is an abstract data structure, struct member don't have any visibility. Only variables that are defined using the struct type can have visibility modifiers. Therefore, you should delete the p …

There's a section in the Solidity docs for this: Units and Globally Available Variables For example, block.timestamp returns the current Unix timestamp recorded in the Ethereum blockchain. …

Solidity cannot handle "txt" or "csv" files directly. In fact, at runtime, all there is the blockchain state. Solidity cannot communicate with the external world (not even via the HTTP protocol). …

Just import the IERC20 interface from OpenZeppelin and then do this: IERC20(contractAddress).balanceOf

It's unclear what you mean by "handle", but assuming you mean "react to an ERC-20 transfer", this is not possible. The ERC-20 standard did not specify callbacks (a.k.a. hooks), unlike other token stan …

ERC165 tackles this problem but it cannot be used for older ERCs. For instance, most ERC20 implementations don't implement it (as of Nov 2018, at least OpenZeppelin doesn't). You could try calling the …

Imagine you have a function like this: function compute(uint256 a, uint256 b) external pure returns (uint256) { return a % b; } Does it revert when b is 0?