Question

我制作了这段代码，它使用类来提取信息objects。我仍然是Class和Object programming的新手，所以我往往会遇到错误。现在我有一个问题我绝对不明白。我尝试过全能的谷歌，用不同的操作员替换部分代码并询问我的同事程序员朋友。似乎没有人知道发生了什么。

问题发生在CompareBooks方法中，它一直告诉我我错过了formal parameter。有人建议在方法中使用:base，但它只创建了2个错误。

namespace ClassProgram
{
    class Book
    {
        public string name;
        public int id;
        public float price;

        public void PrintBookInfo()
        {
            Console.WriteLine("--------------");
            Console.WriteLine("Book Name: " + this.name);
            Console.WriteLine("Book Id: " + this.id);
            Console.WriteLine("Book Price: " + this.price + " dollars");
        }

        public void CompareBooks(Book book1)
        {
            if (this.price > book1.price)
            {
                Console.WriteLine(this.name + " is more expensive than " + book1.name);
            }
        }

        class MainProgram
        {
            static void Main(string[] args)
            {
                Book book = new Book();
                book.name = "C# For Newbies";
                book.id = 01;
                book.price = 10;
                book.PrintBookInfo();
                book.CompareBooks();
                Book book1 = new Book();
                book1.name = "Lord Of The Rings";
                book1.id = 02;
                book1.price = 5;
                book1.PrintBookInfo();
            }
        }
    }
}

Answer 1

当您致电时，您的book.CompareBooks();没有Book个对象作为参数输入。将此与您的签名进行比较：

public void CompareBooks(Book book1) //the Book object is required in the input

因此你得到了错误。＆＃34;形式参数＆＃34;表示 a-must 参数（与C＃中的合成糖optional-parameter相比）。这意味着你必须在方法的输入参数中加入一些东西来调用它。

假设在MainProgram中，它运行如下：

Book book = new Book();
book.name = "C# For Newbies";
book.id = 01;
book.price = 10;
book.PrintBookInfo();
Book book1 = new Book();
book1.name = "Lord Of The Rings";
book1.id = 02;
book1.price = 5;
book1.PrintBookInfo();
book.CompareBooks(book1); //note that this has input now

然后你的代码应该没问题

Answer 2

您不会提供有关您的第一本书应与哪本书进行比较的任何信息。我想你会这样：

Book book = new Book();
book.name = "C# For Newbies";
book.id = 01;
book.price = 10;
book.PrintBookInfo();

Book book1 = new Book();
book1.name = "Lord Of The Rings";
book1.id = 02;
book1.price = 5;
book1.PrintBookInfo();

book.CompareBooks(book1);

没有给出对应于Class中所需形式参数的参数

2 个答案: