IComparable.CompareTo(Object) 方法

參考

定義

命名空間:: System

組件:: System.Runtime.dll

組件:: mscorlib.dll

組件:: netstandard.dll

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

將目前的執行個體與相同型別的另一個物件相比較，並傳回整數，這個整數表示目前的執行個體在排序次序中，位於另一個物件之前、之後或相同位置。

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

參數

obj: Object

與這個執行個體相互比較的物件。

傳回

Int32

值，表示所比較之物件的相對順序。傳回值具有這些意義：

值	意義
小於零	這個執行個體在排序次序中會在 `obj` 之前。
零	這個執行個體在排序次序中的位置和 `obj` 相同。
大於零	這個執行個體在排序順序中會跟在 `obj` 之後。

例外狀況

ArgumentException

obj 與這個執行個體的型別不同。

範例

下列範例說明如何使用 CompareTo 來比較實作 IComparable 的物件與另一個 Temperature 物件。物件 Temperature 會 CompareTo 實作，只要包裝方法的 Int32.CompareTo 呼叫即可。

using namespace System;
using namespace System::Collections;

public ref class Temperature: public IComparable {
   /// <summary>
   /// IComparable.CompareTo implementation.
   /// </summary>
protected:
   // The value holder
   Double m_value;

public:
   virtual Int32 CompareTo( Object^ obj ) {
   
      if (obj == nullptr) return 1;
      
      if ( obj->GetType() == Temperature::typeid ) {
         Temperature^ temp = dynamic_cast<Temperature^>(obj);

         return m_value.CompareTo( temp->m_value );
      }
      throw gcnew ArgumentException(  "object is not a Temperature" );
   }

   property Double Value {
      Double get() {
         return m_value;
      }
      void set( Double value ) {
         m_value = value;
      }
   }

   property Double Celsius  {
      Double get() {
         return (m_value - 32) / 1.8;
      }
      void set( Double value ) {
         m_value = (value * 1.8) + 32;
      }
   }
};

int main()
{
   ArrayList^ temperatures = gcnew ArrayList;
   // Initialize random number generator.
   Random^ rnd = gcnew Random;

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

   // Sort ArrayList.
   temperatures->Sort();
      
   for each (Temperature^ temp in temperatures)
      Console::WriteLine(temp->Value);
   return 0;
}
// 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

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

備註

方法 CompareTo 是由可排序或排序其值的型別所實作。它會由非泛型集合物件的方法自動呼叫，例如 Array.Sort ，以排序陣列的每個成員。如果自訂類別或結構未實 IComparable 作，則無法排序其成員，而且排序作業可以擲回 InvalidOperationException 。

這個方法只是定義，必須由特定類別或實值型別實作，才能生效。傳回值區段中指定之比較的意義 (「之前」、「發生于與相同的位置，而」follows「) 取決於特定實作。

根據定義，任何物件都會比較大於 (或遵循) null ，而兩個 Null 參考會彼此相等。

參數 obj 的類型必須與實作這個介面的類別或實值型別相同， ArgumentException 否則會擲回。

給實施者的注意事項

對於物件 A、B 和 C，下列條件必須為 true： A.CompareTo (A) 必須傳回零。

如果 A.CompareTo (B) 傳回零， 則 B.CompareTo (A) 必須傳回零。

如果 A.CompareTo (B) 傳回零，而 B.CompareTo (C) 傳回零， 則 A.CompareTo (C) 必須傳回零。

如果 A.CompareTo (B) 傳回零以外的值， 則 B.CompareTo (A) 必須傳回相反符號的值。

如果A.CompareTo (B) 傳回 x 的值不等於零，而B.CompareTo (C) 傳回與相同的符號 x 值 y ，則 A.CompareTo (C) 必須傳回與和 y 相同的符號 x 值。

給呼叫者的注意事項

CompareTo(Object)使用方法來判斷類別實例的順序。

適用於

另請參閱

Object

IComparable.CompareTo(Object) 方法

定義

參數

傳回

例外狀況

範例

備註

給實施者的注意事項

給呼叫者的注意事項

適用於

另請參閱

其他資源