编译时错误 - 无法使用实例引用访问成员

Question

我是一个新尝试理解类和类如何工作的人.我正在构建一个小型控制台程序,我正在处理我的'class.cs'文件,我将其命名为'LineItem.cs',因为它将处理我试图让我的控制台应用程序生成的收据上的订单项.

问题:无法使用实例引用访问成员'A070_ 类 _CashRegister.Program.receipt()'; 用类型名称来限定它.(错误行:#21 /列#13)

当我输入'this.color = price;我认为我在#21行上做过这个.

码:

using System;
namespace a070___Classes___CashRegister
{
  class LineItem     // Class name is singular
                     // receipt might be better name for this class?
  {
    /// Class Attributes
    private String product;     // constructor attribute
    private String description;
    private String color;
    private double price;
    private Boolean isAvailable;

    // constructor called to make object => LineItem
    public LineItem(String product, String description, String color, int price, Boolean isAvailable)
    {
        this.product = product;
        this.description = description;
        this.color = color;
        this.price = price;
        this.isAvailable = isAvailable;// might want to do an availability check
    }

    //Getters
    public String GetProduct() {return product;}
    public String GetDescription(){return description;}//Send description
    public String GetColor() {return color;}

    //Setter
    public void SetColor(string color)//we might want to see it in other colors if is option
    { this.color = color; } //changes object color 
  }
}

将调用该类的主文件:

using System;

namespace a070___Classes___CashRegister
{
  class Program
  {
    static void receipt()
    { 
    //stuff goes here - we call various instances of the class to generate some receipts
    }

    static void Main(string[] args)
    {
        //Program CashRegister = new Program();
        //CashRegister.receipt();

        //Program CashRegister = new Program();
        //CashRegister.receipt();

        receipt();// Don't need to instantiate Program, console applications framework will find the static function Main
        //unless changed your project properties.
        //Since reciept is member od Program and static too, you can just call it directly, without qualification.
    }
  }
} 

Answer 1

Program CashRegister = new Program();
CashRegister.receipt();

应该

Program.receipt();

要不就

receipt();

您不需要实例化Program,使用控制台应用程序,框架将找到static function Main(...并通过魔术调用它,除非您已更改项目属性.

既然receipt是一个成员Program和static也,你可以直接调用它,没有资格.

该receipt()函数是,static但您正在尝试从实例调用它.

你没有显示receipt声明的位置或你在哪里调用它所以我无法提供更多帮助.

也许你有一行代码,其中有一个表达式,如,

... this.receipt() ...

要么

... yourInstance.receipt() ...

但应该是,

... Type.receipt() ...