结构和枚举

结构可用来表示二维，三维数据。

枚举表示有限数据结合。

他们都是值类型

结构struct 

using System;
  
struct Point
{
    public double x, y;
    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }
    public double R(){
        return Math.Sqrt(x*x+y*y);
    }
}
  
class Test
{
    static void Main() {
        Point[] points = new Point[100];
        for (int i = 0; i < 100; i++)
            points[i] = new Point(i, i*i);
    }
}

枚举 enum

using System;
enum LightColor 
{
    Red,
    Yellow,
    Green
}
class TrafficLight
{
    public static void WhatInfo(LightColor color) {
        switch(color) {
            case LightColor.Red:
                Console.WriteLine(  "Stop!" );
                break;
            case LightColor.Yellow:
                Console.WriteLine(  "Warning!" );
                break;
            case LightColor.Green:
                Console.WriteLine(  "Go!" );
                break;
            default:
                break;
        }
    }
}
  
class Test
{
    static void Main()
    {
        LightColor c = LightColor.Red;
        Console.WriteLine( c.ToString() );
        TrafficLight.WhatInfo( c );
    }
}