C# 數組排序 Array.Sort 方法

參考 https://docs.microsoft.com/zh-cn/dotnet/api/system.array.sort?view=net-5.0

命名空間：System

對一維數組進行排序

重載：

我們主要介紹這一個重載：

指定 IComparer 規則

例如，想要對一個int數組遞減排序

using System;
using System.Collections;

public class DecComparer : IComparer<int>
{
    public int Compare(int a, int b)
    {
        return a - b;
    }
}

// Array.Sort(arr, 0, arr.Length, new DecComparer());

如果 comparer 為 null ，中指定范圍內的元素中的每個元素都 array 必須實現 IComparable 接口，以便與中的每個其他元素進行比較 array 。

繼承 IComparable 接口

using System;
using System.Collections;

public class Temperature : IComparable
{
    protected double temperatureF;
    
    public int CompareTo(object obj){
        if(obj == null) return 1;
        
        Temperature otherTemperature = obj as Temperature;
        
        if(otherTemperature != null){
            return this.temperatureF.CompareTo(otherTemperature.temperatureF);
        }else{
            throw new ArgumentException("Object is not a Temperature");
        }
    }
    
    public double Fahrenheit
    {
        get
        {
            return this.temperatureF;
        }
        set {
            this.temperatureF = value;
        }
    }

    public double Celsius
    {
        get
        {
            return (this.temperatureF - 32) * (5.0/9);
        }
        set
        {
            this.temperatureF = (value * 9.0/5) + 32;
        }
    }
}


public class CompareTemperatures
{
   public static void Main()
   {
      ArrayList temperatures = new ArrayList();
      // Initialize random number generator.
      Random rnd = new Random();

      // Generate 10 temperatures between 0 and 100 randomly.
      for (int ctr = 1; ctr <= 10; ctr++)
      {
         int degrees = rnd.Next(0, 100);
         Temperature temp = new Temperature();
         temp.Fahrenheit = degrees;
         temperatures.Add(temp);
      }

      // Sort ArrayList.
      temperatures.Sort();

      foreach (Temperature temp in temperatures)
         Console.WriteLine(temp.Fahrenheit);
   }
}
// The example displays the following output to the console (individual
// values may vary because they are randomly generated):
//       2
//       7
//       16
//       17
//       31
//       37
//       58
//       66
//       72
//       95