... }
}
pragma solidity ^0.6.2;
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
interface IERC20 {
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Retur...
...ier: MIT
pragma solidity 0.8.20;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
contract A is ERC20{
constructor()ERC20("",""){}
//check a address is a contract
function checkContract(address addr)public view returns(bool){
uint size;
//以太坊的...