IComparable<T>.CompareTo(T) Methode

Definition

Vergleicht die aktuelle Instanz mit einem anderen Objekt vom selben Typ und gibt eine ganze Zahl zurück, die angibt, ob die aktuelle Instanz in der Sortierreihenfolge vor oder nach dem anderen Objekt oder an derselben Position auftritt.

public:
 int CompareTo(T other);
public int CompareTo (T other);
public int CompareTo (T? other);
abstract member CompareTo : 'T -> int
Public Function CompareTo (other As T) As Integer

Parameter

other
T

Ein Objekt, das mit dieser Instanz verglichen werden soll.

Gibt zurück

Int32

Ein Wert, der die relative Reihenfolge der verglichenen Objekte angibt. Der Rückgabewert hat folgende Bedeutung:

Wert Bedeutung
Kleiner als 0 (null) Diese Instanz befindet sich in der Sortierreihenfolge vor other.
Zero Diese Instanz tritt in der Sortierreihenfolge an der gleichen Position wie other auf.
Größer als 0 (null) Diese Instanz folgt in der Sortierreihenfolge auf other.

Beispiele

Im folgenden Codebeispiel wird die Implementierung IComparable<T> eines einfachen Temperature Objekts veranschaulicht. Im Beispiel wird eine SortedList<TKey,TValue> Auflistung von Zeichenfolgen mit Temperature Objektschlüsseln erstellt und der Liste aus der Sequenz mehrere Temperaturen und Zeichenfolgen hinzugefügt. Im Aufruf der Methode verwendet die SortedList<TKey,TValue> Auflistung die IComparable<T> Implementierung zum Sortieren der Add Listeneinträge, die dann in der Reihenfolge der steigenden Temperatur angezeigt werden.

#using <System.dll>

using namespace System;
using namespace System::Collections::Generic;

public ref class Temperature: public IComparable<Temperature^> {

protected:
   // The underlying temperature value.
   Double m_value;

public:
   // Implement the generic CompareTo method with the Temperature class 
   // as the Type parameter. 
   virtual Int32 CompareTo( Temperature^ other ) {
   
      // If other is not a valid object reference, this instance 
      // is greater.
      if (other == nullptr) return 1;
      
      // The temperature comparison depends on the comparison of the
      // the underlying Double values. 
      return m_value.CompareTo( other->m_value );
   }

       // Define the is greater than operator.
    bool operator>=  (Temperature^ other)
    {
       return CompareTo(other) >= 0;
    }
    
    // Define the is less than operator.
    bool operator<  (Temperature^ other)
    {
       return CompareTo(other) < 0;
    }
    
       // Define the is greater than or equal to operator.
    bool operator>  (Temperature^ other)
    {
       return CompareTo(other) > 0;
    }
    
    // Define the is less than or equal to operator.
    bool operator<=  (Temperature^ other)
    {
       return CompareTo(other) <= 0;
    }

   property Double Celsius {
      Double get() {
         return m_value + 273.15;
      }
   }

   property Double Kelvin {
      Double get() {
         return m_value;
      }
      void set( Double value ) {
         if (value < 0)
            throw gcnew ArgumentException("Temperature cannot be less than absolute zero.");
         else
            m_value = value;
      }
   }

   Temperature(Double kelvins) {
      this->Kelvin = kelvins;
   }
};

int main() {
   SortedList<Temperature^, String^>^ temps = 
      gcnew SortedList<Temperature^, String^>();

   // Add entries to the sorted list, out of order.
   temps->Add(gcnew Temperature(2017.15), "Boiling point of Lead");
   temps->Add(gcnew Temperature(0), "Absolute zero");
   temps->Add(gcnew Temperature(273.15), "Freezing point of water");
   temps->Add(gcnew Temperature(5100.15), "Boiling point of Carbon");
   temps->Add(gcnew Temperature(373.15), "Boiling point of water");
   temps->Add(gcnew Temperature(600.65), "Melting point of Lead");

   for each( KeyValuePair<Temperature^, String^>^ kvp in temps )
   {
      Console::WriteLine("{0} is {1} degrees Celsius.", kvp->Value, kvp->Key->Celsius);
   }
}
/* The example displays the following output:
      Absolute zero is 273.15 degrees Celsius.
      Freezing point of water is 546.3 degrees Celsius.
      Boiling point of water is 646.3 degrees Celsius.
      Melting point of Lead is 873.8 degrees Celsius.
      Boiling point of Lead is 2290.3 degrees Celsius.
      Boiling point of Carbon is 5373.3 degrees Celsius.
*/
using System;
using System.Collections.Generic;

public class Temperature : IComparable<Temperature>
{
    // Implement the generic CompareTo method with the Temperature
    // class as the Type parameter.
    //
    public int CompareTo(Temperature other)
    {
        // If other is not a valid object reference, this instance is greater.
        if (other == null) return 1;

        // The temperature comparison depends on the comparison of
        // the underlying Double values.
        return m_value.CompareTo(other.m_value);
    }

    // Define the is greater than operator.
    public static bool operator >  (Temperature operand1, Temperature operand2)
    {
       return operand1.CompareTo(operand2) > 0;
    }

    // Define the is less than operator.
    public static bool operator <  (Temperature operand1, Temperature operand2)
    {
       return operand1.CompareTo(operand2) < 0;
    }

    // Define the is greater than or equal to operator.
    public static bool operator >=  (Temperature operand1, Temperature operand2)
    {
       return operand1.CompareTo(operand2) >= 0;
    }

    // Define the is less than or equal to operator.
    public static bool operator <=  (Temperature operand1, Temperature operand2)
    {
       return operand1.CompareTo(operand2) <= 0;
    }

    // The underlying temperature value.
    protected double m_value = 0.0;

    public double Celsius
    {
        get
        {
            return m_value - 273.15;
        }
    }

    public double Kelvin
    {
        get
        {
            return m_value;
        }
        set
        {
            if (value < 0.0)
            {
                throw new ArgumentException("Temperature cannot be less than absolute zero.");
            }
            else
            {
                m_value = value;
            }
        }
    }

    public Temperature(double kelvins)
    {
        this.Kelvin = kelvins;
    }
}

public class Example
{
    public static void Main()
    {
        SortedList<Temperature, string> temps =
            new SortedList<Temperature, string>();

        // Add entries to the sorted list, out of order.
        temps.Add(new Temperature(2017.15), "Boiling point of Lead");
        temps.Add(new Temperature(0), "Absolute zero");
        temps.Add(new Temperature(273.15), "Freezing point of water");
        temps.Add(new Temperature(5100.15), "Boiling point of Carbon");
        temps.Add(new Temperature(373.15), "Boiling point of water");
        temps.Add(new Temperature(600.65), "Melting point of Lead");

        foreach( KeyValuePair<Temperature, string> kvp in temps )
        {
            Console.WriteLine("{0} is {1} degrees Celsius.", kvp.Value, kvp.Key.Celsius);
        }
    }
}
/* This example displays the following output:
      Absolute zero is -273.15 degrees Celsius.
      Freezing point of water is 0 degrees Celsius.
      Boiling point of water is 100 degrees Celsius.
      Melting point of Lead is 327.5 degrees Celsius.
      Boiling point of Lead is 1744 degrees Celsius.
      Boiling point of Carbon is 4827 degrees Celsius.
*/
open System
open System.Collections.Generic

type Temperature(kelvins: double) =
    // The underlying temperature value.
    let mutable kelvins = kelvins

    do 
        if kelvins < 0. then
            invalidArg (nameof kelvins) "Temperature cannot be less than absolute zero."

    // Define the is greater than operator.
    static member op_GreaterThan (operand1: Temperature, operand2: Temperature) =
        operand1.CompareTo operand2 > 0

    // Define the is less than operator.
    static member op_LessThan (operand1: Temperature, operand2: Temperature) =
        operand1.CompareTo operand2 < 0

    // Define the is greater than or equal to operator.
    static member op_GreaterThanOrEqual (operand1: Temperature, operand2: Temperature) =
        operand1.CompareTo operand2 >= 0

    // Define the is less than or equal to operator.
    static member op_LessThanOrEqual (operand1: Temperature, operand2: Temperature) =
        operand1.CompareTo operand2 <= 0

    member _.Celsius =
        kelvins - 273.15

    member _.Kelvin
        with get () =
            kelvins
        and set (value) =
            if value < 0. then
                invalidArg (nameof value) "Temperature cannot be less than absolute zero."
            else
                kelvins <- value

    // Implement the generic CompareTo method with the Temperature
    // class as the Type parameter.
    member _.CompareTo(other: Temperature) =
        // If other is not a valid object reference, this instance is greater.
        match box other with
        | null -> 1
        | _ ->
            // The temperature comparison depends on the comparison of
            // the underlying Double values.
            kelvins.CompareTo(other.Kelvin)

    interface IComparable<Temperature> with
        member this.CompareTo(other) = this.CompareTo other

let temps = SortedList()

// Add entries to the sorted list, out of order.
temps.Add(Temperature 2017.15, "Boiling point of Lead")
temps.Add(Temperature 0., "Absolute zero")
temps.Add(Temperature 273.15, "Freezing point of water")
temps.Add(Temperature 5100.15, "Boiling point of Carbon")
temps.Add(Temperature 373.15, "Boiling point of water")
temps.Add(Temperature 600.65, "Melting point of Lead")

for kvp in temps do
    printfn $"{kvp.Value} is {kvp.Key.Celsius} degrees Celsius."

//  This example displays the following output:
//       Absolute zero is -273.15 degrees Celsius.
//       Freezing point of water is 0 degrees Celsius.
//       Boiling point of water is 100 degrees Celsius.
//       Melting point of Lead is 327.5 degrees Celsius.
//       Boiling point of Lead is 1744 degrees Celsius.
//       Boiling point of Carbon is 4827 degrees Celsius.
Imports System.Collections.Generic

Public Class Temperature
    Implements IComparable(Of Temperature)

    ' Implement the generic CompareTo method with the Temperature class 
    ' as the type parameter. 
    '
    Public Overloads Function CompareTo(ByVal other As Temperature) As Integer _
        Implements IComparable(Of Temperature).CompareTo

        ' If other is not a valid object reference, this instance is greater.
        If other Is Nothing Then Return 1
        
        ' The temperature comparison depends on the comparison of the
        ' the underlying Double values. 
        Return m_value.CompareTo(other.m_value)
    End Function
    
    ' Define the is greater than operator.
    Public Shared Operator >  (operand1 As Temperature, operand2 As Temperature) As Boolean
       Return operand1.CompareTo(operand2) > 0
    End Operator
    
    ' Define the is less than operator.
    Public Shared Operator <  (operand1 As Temperature, operand2 As Temperature) As Boolean
       Return operand1.CompareTo(operand2) < 0
    End Operator

    ' Define the is greater than or equal to operator.
    Public Shared Operator >=  (operand1 As Temperature, operand2 As Temperature) As Boolean
       Return operand1.CompareTo(operand2) >= 0
    End Operator
    
    ' Define the is less than operator.
    Public Shared Operator <=  (operand1 As Temperature, operand2 As Temperature) As Boolean
       Return operand1.CompareTo(operand2) <= 0
    End Operator

    ' The underlying temperature value.
    Protected m_value As Double = 0.0

    Public ReadOnly Property Celsius() As Double
        Get
            Return m_value - 273.15
        End Get
    End Property

    Public Property Kelvin() As Double
        Get
            Return m_value
        End Get
        Set(ByVal Value As Double)
            If value < 0.0 Then 
                Throw New ArgumentException("Temperature cannot be less than absolute zero.")
            Else
                m_value = Value
            End If
        End Set
    End Property

    Public Sub New(ByVal kelvins As Double)
        Me.Kelvin = kelvins 
    End Sub
End Class

Public Class Example
    Public Shared Sub Main()
        Dim temps As New SortedList(Of Temperature, String)

        ' Add entries to the sorted list, out of order.
        temps.Add(New Temperature(2017.15), "Boiling point of Lead")
        temps.Add(New Temperature(0), "Absolute zero")
        temps.Add(New Temperature(273.15), "Freezing point of water")
        temps.Add(New Temperature(5100.15), "Boiling point of Carbon")
        temps.Add(New Temperature(373.15), "Boiling point of water")
        temps.Add(New Temperature(600.65), "Melting point of Lead")

        For Each kvp As KeyValuePair(Of Temperature, String) In temps
            Console.WriteLine("{0} is {1} degrees Celsius.", kvp.Value, kvp.Key.Celsius)
        Next
    End Sub
End Class

' The example displays the following output:
'      Absolute zero is -273.15 degrees Celsius.
'      Freezing point of water is 0 degrees Celsius.
'      Boiling point of water is 100 degrees Celsius.
'      Melting point of Lead is 327.5 degrees Celsius.
'      Boiling point of Lead is 1744 degrees Celsius.
'      Boiling point of Carbon is 4827 degrees Celsius.
'

Hinweise

CompareTo stellt eine stark typierte Vergleichsmethode für die Reihenfolge von Elementen eines generischen Auflistungsobjekts bereit. Aus diesem Grund wird sie in der Regel nicht direkt vom Entwicklercode aufgerufen. Stattdessen wird sie automatisch durch Methoden wie List<T>.Sort() z. B. und Add.

Diese Methode ist nur eine Definition und muss durch einen bestimmten Klassen- oder Werttyp implementiert werden, um Auswirkungen zu haben. Die Bedeutung der im Abschnitt "Rückgabewerte" angegebenen Vergleiche ("vorgestellt", "tritt in derselben Position wie", und "folgt") von der jeweiligen Implementierung ab.

Durch Definition vergleicht jedes Objekt größer nullals , und zwei NULL-Verweise vergleichen einander.

Hinweise für Ausführende

Für Objekte A, B und C muss folgendes wahr sein: A.CompareTo(A) ist erforderlich, um Null zurückzugeben.

Wenn A.CompareTo(B) null zurückgibt, ist B.CompareTo(A) erforderlich, um Null zurückzugeben.

Wenn A.CompareTo(B) Null zurückgibt und B.CompareTo(C) null zurückgibt, ist A.CompareTo(C) erforderlich, um Null zurückzugeben.

Wenn A.CompareTo(B) einen anderen Wert als null zurückgibt, ist B.CompareTo(A) erforderlich, um einen Wert des gegenteiligen Zeichens zurückzugeben.

Wenn A.CompareTo(B) einen Wert zurückgibt, der nicht null ist, und B.CompareTo(C) gibt einen Wert desselben Zeichens zurück, xund dann ist A.CompareTo(C) erforderlich, um einen Wert x y desselben Zeichens x wie und y.

Hinweise für Aufrufer

Verwenden Sie die CompareTo(T) Methode, um die Reihenfolge der Instanzen einer Klasse zu bestimmen.

Gilt für:

Siehe auch