執行以下
// SPDX-License-Identifier: MIT pragma solidity 0.7.5; import {Counters} from "@openzeppelin/contracts/utils/Counters.sol"; contract MyToken is ERC721, Pausable, Ownable { using Counters for Counters.Counter; Counters.Counter private _tokenIdCounter; function safeMint(address receiver) public onlyOwner { uint256 tokenId = _tokenIdCounter.current(); _safeMint(_receiver, tokenId); _tokenIdCounter.increment(); }
報錯
ParserError: Source "project:/node_modules/openzeppelin/contracts/utils/Counters.sol" not found --> project:/contracts/tests.sol:4:1: | 4 | import "../node_modules/openzeppelin/contracts/utils/Counters.sol"; | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
使用 unit 型別代替 counter
contract MyToken is ERC721, Pausable, Ownable { uint256 private _tokenIdCounter; function safeMint(address receiver) public onlyOwner { uint256 tokenId = _tokenIdCounter; _safeMint(_receiver, tokenId); _tokenIdCounter += 1; } }