here’s the link https://docs.openzeppelin.com/contracts/4.x/erc721
the compile result is
DeclarationError: Undeclared identifier. _setTokenURI(newItemId, tokenURI); ^^^^^^^^^^^^
the compiler versions is
Truffle v5.3.0 (core: 5.3.0) Node v12.18.2
my question is where sample code of ERC721 for version ^4.0.0 ?
openzeppelin broke up the contract to have the tokenURI stuff be its own extension (check out extensions here). So in order to get the token URI stuff, you’d need to inherit ERC721URIStorage instead of ERC721. (ERC721URIStorage inherits ERC721).
ERC721URIStorage
ERC721
You can also use the Contracts Wizard https://zpl.in/wizard