IComparable.CompareTo(Object) 方法

public:
 int CompareTo(System::Object ^ obj);

public int CompareTo(object obj);

public int CompareTo(object? obj);

abstract member CompareTo : obj -> int

Public Function CompareTo (obj As Object) As Integer

参数

返回

一个值，该值指示所比较对象的相对顺序。 返回值具有以下含义：

例外

示例

下面的示例演示如何CompareTo将实现Temperature的对象与另一个IComparable对象进行比较。 对象Temperature只需包装对方法的CompareTo调用即可实现Int32.CompareTo。

using System;
using System.Collections;

public class Temperature : IComparable
{
    // The temperature value
    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

open System
open System.Collections

type Temperature() =
    // The temperature value
    let mutable temperatureF = 0.

    interface IComparable with
        member _.CompareTo(obj) =
            match obj with 
            | null -> 1
            | :? Temperature as other -> 
                temperatureF.CompareTo other.Fahrenheit
            | _ ->
                invalidArg (nameof obj) "Object is not a Temperature"

    member _.Fahrenheit 
        with get () =
            temperatureF
        and set (value) = 
            temperatureF <- value

    member _.Celsius
        with get () =
            (temperatureF - 32.) * (5. / 9.)
        and set (value) =
            temperatureF <- (value * 9. / 5.) + 32.

let temperatures = ResizeArray()

// Initialize random number generator.
let rnd = Random()

// Generate 10 temperatures between 0 and 100 randomly.
for _ = 1 to 10 do
    let degrees = rnd.Next(0, 100)
    let temp = Temperature(Fahrenheit=degrees)
    temperatures.Add temp

// Sort ResizeArray.
temperatures.Sort()

for temp in temperatures do
    printfn $"{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

Imports System.Collections

Public Class Temperature
    Implements IComparable
    ' The temperature value
    Protected temperatureF As Double

    Public Overloads Function CompareTo(ByVal obj As Object) As Integer _
        Implements IComparable.CompareTo
        
        If obj Is Nothing Then Return 1

        Dim otherTemperature As Temperature = TryCast(obj, Temperature)
        If otherTemperature IsNot Nothing Then
            Return Me.temperatureF.CompareTo(otherTemperature.temperatureF)
        Else
           Throw New ArgumentException("Object is not a Temperature")
        End If   
    End Function

    Public Property Fahrenheit() As Double
        Get
            Return temperatureF
        End Get
        Set(ByVal Value As Double)
            Me.temperatureF = Value
        End Set
    End Property

    Public Property Celsius() As Double
        Get
            Return (temperatureF - 32) * (5/9)
        End Get
        Set(ByVal Value As Double)
            Me.temperatureF = (Value * 9/5) + 32
        End Set
    End Property
End Class

Public Module CompareTemperatures
   Public Sub Main()
      Dim temperatures As New ArrayList
      ' Initialize random number generator.
      Dim rnd As New Random()
      
      ' Generate 10 temperatures between 0 and 100 randomly.
      For ctr As Integer = 1 To 10
         Dim degrees As Integer = rnd.Next(0, 100)
         Dim temp As New Temperature
         temp.Fahrenheit = degrees
         temperatures.Add(temp)   
      Next

      ' Sort ArrayList.
      temperatures.Sort()
      
      For Each temp As Temperature In temperatures
         Console.WriteLine(temp.Fahrenheit)
      Next      
   End Sub
End Module
' 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

注解

该方法 CompareTo 由可排序或排序其值的类型实现。 它由非泛型集合对象的方法（例如 Array.Sort）自动调用，以便对数组的每个成员进行排序。 如果自定义类或结构未实现IComparable，则无法对成员进行排序，排序操作可以引发 。InvalidOperationException

此方法只是一个定义，必须由特定的类或值类型实现才能生效。 返回值节中指定的比较的含义（“前面”、“发生于同一位置”和“follows”）取决于特定实现。

根据定义，任何对象都比较大于（或后跟）， null两个空引用相互比较相等。

参数 obj必须与实现此接口的类或值类型相同;否则将引发一个 ArgumentException 参数。

实施者说明

对于对象 A、B 和 C，必须执行以下操作：

A.CompareTo(A) 必须返回零。

如果 A.CompareTo(B) 返回零，则必须 B.CompareTo(A) 返回零。

如果 A.CompareTo(B) 返回零并 B.CompareTo(C) 返回零，则必须 A.CompareTo(C) 返回零。

如果 A.CompareTo(B) 返回除零以外的值，则必须 B.CompareTo(A) 返回相反符号的值。

如果 A.CompareTo(B) 返回的值“x”不等于零，并且 B.CompareTo(C) 返回与“x”相同的符号的值“y”，则必须 A.CompareTo(C) 返回与“x”和“y”相同的符号的值。

调用方说明

CompareTo(Object)使用该方法确定类实例的排序。

另请参阅

• Object