class 方法 "does not contain definition for and no extension method"

Question

我正在尝试学习 C# 教程，但我被困在 class 方法上，它说它找不到方法，即使它在那里。很明显我错过了什么，但是什么？

我认为这与在方法 'DistanceTo' 中找不到 class 'Point' 有关，因为在参数 'Point' 中没有在 Visual Studio.

非常感谢任何能帮助我继续学习的人;)

主要代码文件：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace Verita
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Button1_Click(object sender, RoutedEventArgs e)
        {

            Point firstPoint = new Point(0, 0);
            Point secondPoint = new Point(100, 100);

            Output.Text = firstPoint.X.ToString();
            Output.Text += secondPoint.Y.ToString();

            double distance = firstPoint.DistanceTo(secondPoint);
            Output.Text += distance;


        }    
    }
}

Class 文件：

using System;

/// <summary>
/// Summary description for Class1
/// </summary>
public class Point
{
    private int x, y;

    public Point()
    {
        this.x = -1;
        this.y = -1;
    }

    public Point(int x, int y)
    {
        this.x = x;
        this.y = y;
    }

    public double DistanceTo(Point other)
    {
        int xDiff = this.x - other.x;
        int yDiff = this.y - other.y;

        double distance = Math.Sqrt((xDiff * xDiff) + (yDiff * yDiff));
        return distance;
    }


}

编辑：问题已解决！感谢 habib 和 drew。我为此编辑了代码，现在它工作正常：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace Verita
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Button1_Click(object sender, RoutedEventArgs e)
        {

            Classes.Userpoint firstPoint = new Classes.Userpoint(0, 0);
            Classes.Userpoint secondPoint = new Classes.Userpoint(100, 100);

            Output.Text = firstPoint.x.ToString();
            Output.Text += secondPoint.y.ToString();

            double distance = firstPoint.DistanceTo(secondPoint);
            Output.Text += distance;


        }
    }  
}

namespace Classes
{

    public class Userpoint
    {
        public int x, y;

        public Userpoint()
        {
            this.x = -1;
            this.y = -1;
        }

        public Userpoint(int x, int y)
        {
            this.x = x;
            this.y = y;
        }

        public double DistanceTo(Userpoint other)
        {
            int xDiff = this.x - other.x;
            int yDiff = this.y - other.y;

            double distance = Math.Sqrt((xDiff * xDiff) + (yDiff * yDiff));
            return distance;
        }


    }

}

Answer 1

查看错误（DistanceTo 未找到）并且属性 X 和 Y 可用，我只能想象您正在使用 Point structure 由框架提供，您原来的 class 没有在任何地方使用。

我建议您将 class 名称修改为不同的名称，或者指定一个名称空间并将其与该名称空间一起使用。

namespace Verita
{
    public class Point
    {
        private int x, y;

然后在使用的时候：

Verita.Point firstPoint = new Verita.Point(0, 0);

但是现在您将遇到新的错误，因为您没有将 X 和 Y 公开为 public。

Answer 2

除了 Habib's 答案之外，您的 x 和 y 属性需要设置为 public 才能访问：

public int x { get; set; }
public int y { get; set; }

此外，请检查您尝试访问的属性是否区分大小写。

class 方法 "does not contain definition for and no extension method"

class method "does not contain definition for and no extension method"

c#

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