...
uint256 NFTPrice = 0.1 ether;
/// @dev purchase() accepts ETH and marks the owner of the given tokenId as the caller address
/// @param _tokenId - the fake NFT token Id to purchase
function purchase(uint256 _tokenId) external payable {
require(msg.value == NFTPrice, "...
...unique identifier is determined by the position of the offer in the array, and is converted to each other through a fixed algorithm (toindex(), toaddress())
//唯一标识通过报价单在数组中的位置确定,通过固定的算法(toIndex(), toAddress())来互相转化
a...