Library System: Smart Contract

これはとしょかんのシステムです

pragma solidity ^0.4.25; //version

。

contract Library {

//This is the structure of the contract
  struct Book {
    string bookTitle;
    bool inTheShelf;
    address user;
  }

//Declaration of two books
  Book book ＝ Book("book1",true,address(0));
  Book book2　＝ Book("book2",true,address(0));

//This is an array container of the books
  Book[] books;

//calls first
//This is the constructor of the smart contract
  constructor() public {      
      books.push(book);
      books.push(book2);
  }

//This is the function for borrowBook
  function borrowBook(uint i) public {
    require(!books[i].inTheShelf);
    books[i].inTheShelf = false;
    books[i].user = msg.sender;
  }

//This is the function for returnBook
  function returnBook(uint i) public {
    require(books[i].inTheShelf);
    require(books[i].user == msg.sender);
    books[i].intheShelf = true;
    books[i].user = address(0);
  }

}