Question

每当我尝试编译我的作业时，我都会收到此错误

(unresolved_dot_expr type='@lvalue [Book]' location=/Users/BandManFabo/Desktop/Lab03/Lab03/Bookstore.swift:18:9 range=[/Users/BandManFabo/Desktop/Lab03/Lab03/Bookstore.swift:18:9 - line:18:9] field 'books' function_ref=unapplied

我正在使用一个名为Book的类，它有点像Bookstore中的书籍模型，这是另一个类。 Book.swift位于

之下

import Foundation

class Book {
    private var title:String
    private var numOfPages:Int
    private var price: Double
    private var quantity: Int

    init(title:String,pages:Int,price:Double,quantity:Int) {
        self.title = title
        self.numOfPages = pages
        self.price = price
        self.quantity = quantity
    }
    public func getTitle() -> String {
        return self.title
    }
    public func getPrice() -> Double {
        return self.price
    }
    public func getQuantity() -> Int {
        return self.quantity
    }
    public func toString() -> String {
        return "Title: \(self.title)\nNumber Of Pages: \(self.numOfPages)\nPrice: \(self.price)\nQuantity: \(self.quantity)"
    }
    public func subtractQuantity(amount: Int){
        self.quantity = getQuantity() - amount
    }
    public func addQuantity(amount: Int){
        self.quantity = getQuantity() + amount

    }
}

Bookstore使用此类运行

import Foundation

class Bookstore {
    private var totalbooks:Int
    private var gross: Double
    private static let MAXNUMOFBOOKS:Int = 1000
    private var books: [Book]
    //empty constructor for the bookstore
    init() {
        books = [Book](repeatElement(Book, count: Bookstore.MAXNUMOFBOOKS))
        totalbooks = 0
        gross = 0.0
    }

   /* Adds a new book to this bookstore.
   * @param b the book to add
   */
    public func addBook(b:Book){
        if Bookstore.MAXNUMOFBOOKS < books.count{
            books.append(b)
            totalbooks = totalbooks+1
        }else{
             print("\nBookStore: I cannot add a new book into stock.")
        }
    }

    /**
     * Adds a certain quantity of a book already in stock.
     *
     * @param title the title of the the book
     * @param quantity amount of copies to add
     */
    public func addBookQuantity(title:String , quantity:Int){
         // Search for the book...if found adjust the quantity,
        // otherwise, inform the user that the book is not available
        for currentBook in books {
            if currentBook.getTitle() == title{
                currentBook.addQuantity(amount: quantity)
                return
            }//end of if
        }//end of for
        // Book is not found in the bookstore
print("\nBookStore: I cannot increment the quantity of the book titled");
  print("'\(title)' because it is not available in the bookstore.");
    }// addBookQuantity

    /**
     * Checks if at least a certain number of copies of a particular book are in
     * stock. Note: You can use this method to check if a book is already in the
     * bookstore. This way, you won't create duplicate records of the same book.
     *
     * @param title the title of the book to search for
     * @param quantity the desired number of copies
     * @return
     * @returns true if title exists with specified quantity; otherwise false
     */
    public func inStock(title:String, quantity:Int) -> Bool {
        // Search for the book...if found, adjust the quantity.
        // otherwise, Book not in the BookStore.
        for currentBook in books {
            if currentBook.getTitle() == title{
                if quantity <= currentBook.getQuantity(){
                    return true
                }else{
                    return false
                }
            }//end of if
        }//end of for
        //Book not present
        return false
    }

    /**
     * Sells a particular number of copies of a certain book. If successful
     * (i.e. enough books are in stock to sell), the quantity of the book is
     * adjusted. Otherwise, no books are sold.
     *
     * @param title the title of the book to sell
     * @param quantity the amount of books to sell
     * @return
     * @returns true if successful; otherwise false
     */
    public func sellBook(title:String, quantity:Int) -> Bool {
        var sellCheck: Bool = false
        //will check to see if the books are instock
        let retval:Bool = inStock(title: title, quantity: quantity)
        //will do some operation if it is instock
        if retval {
            for currentBook in books {
                if !sellCheck{
                    if currentBook.getTitle() == title{
                        currentBook.subtractQuantity(amount: quantity)
                        gross = gross + currentBook.getPrice() * Double(quantity)
                        sellCheck = true
                    }//end of most inner if
                }//end of inner if
            }//end of outer for
        }//end of outer if
        return retval
    }

    /**
     * Lists information about each book in the bookstore
     */
    public func listBooks(){
        print("\nAll Books In Store and Info\n===============")
        for currentBook in books {
            print(currentBook.toString())
        }
    }
    /**
     * Lists the titles of all the books in the bookstore
     */
    public func listTitles(){
        // List all books titles
        print("\nTitles of Books\n===============")
        for currentBook in books {
            print(currentBook.getTitle())
        }
    }

    /**
     * Returns the gross income of this bookstore.
     *
     * @return
     * @returns gross income
     */
    public func getIncome() -> Double {
        return gross
    }

}

不完全确定分段错误的来源。我感谢任何帮助

Answer 1

修改BookStore类中的init方法

amqplib-easy

Swift程序中的分段错误11

1 个答案: