C＃名称在当前上下文中不存在

Question

下面是我的主要代码，下面的代码块是我的book类。我是c＃的新手，之前没有遇到过这个错误。我在第39和48行遇到错误。两个都是printInformation()电话。错误是

名称'printInformation'在当前上下文中不存在

我不知道该怎么做，我尝试将书类和主类中的所有代码放入一个单独的文件中，其中所有代码都在一起，并且不会出错。

这是否意味着我需要做的事情就公共和私人类所使用的还是别的。我有值title，author，price和isbn的公共getter和setter。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;


namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Enter the amount of books you have, followed by the number 1 or number 2 seperated by a space");
            Console.Write("Enter 1 if you would like to sort the books by price in ascending order");
            Console.WriteLine("Enter 2 if you would like to sort the books by title alphabetically.");
            string number = Console.ReadLine();
            string[] numberArray = number.Split(' ');
            List<Book> bookList = new List<Book>();

            // for the number entered input values
            for (int i = 0; i < Convert.ToInt16(numberArray[0]); i++)
            {
                bookList.Add(new Book
                {
                    Title = Console.ReadLine(),
                    Author = Console.ReadLine(),
                    Price = Convert.ToDouble(Console.ReadLine()),
                    ISBN = Console.ReadLine()
                });
            }
            // sorting based on condition given
            if (Convert.ToInt16(numberArray[1]) == 1)
            {
                var sortedList = from book in bookList orderby book.Price select book;

                foreach (var book in sortedList)
                {
                    printInformation(book.Title, book.Author, book.Price, book.ISBN);
                }
            }
            else
            {
                var sortedList = from book in bookList orderby book.Title select book;

                foreach (var book in sortedList)
                {
                    printInformation(book.Title, book.Author, book.Price, book.ISBN);
                }
            }

            // added this to hold the console window
            Console.ReadLine();
        }
    }
}

预订课程：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    public class Book
    {
        // private fields
        private string title;
        private string author;
        private double price;
        private string isbn;

        public static void printInformation(string _title, string _author, double _price, string _isbn)
        {
            Console.WriteLine(_title + " written by " + _author + " is " + _price.ToString() + " dollars, with ISBN " + _isbn);
        }
    }
}

Answer 1

printInformation方法在Book类中声明为static，因此您需要调用它来指定类型名称：

Book.printInformation(book.Title, book.Author, book.Price, book.ISBN);

顺便说一句，你不需要这个方法，如果你想要一个Book的字符串表示，更好的方法是覆盖ToString类中的Book方法。