# IComparableIComparableIComparableIComparable Interface

## Definition

Definiert eine generalisierte, typspezifische Vergleichsmethode, die von einem Werttyp oder von einer Klasse implementiert wird, um die eigenen Instanzen zu sortieren.Defines a generalized type-specific comparison method that a value type or class implements to order or sort its instances.

``public interface class IComparable``
``````[System.Runtime.InteropServices.ComVisible(true)]
public interface IComparable``````
``type IComparable = interface``
``Public Interface IComparable``
Abgeleitet
Attribute

## Beispiele

Im folgenden Beispiel wird die Implementierung von IComparable und die erforderliche CompareTo -Methode veranschaulicht.The following example illustrates the implementation of IComparable and the requisite CompareTo method.

``````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;
}

// 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;
}

// 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
``````
``````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
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
``````

## Hinweise

Diese Schnittstelle wird von Typen implementiert, deren Werte sortiert oder sortiert werden können.This interface is implemented by types whose values can be ordered or sorted. Es erfordert, dass implementierende Typen eine einzelne Methode CompareTo(Object)definieren,, die angibt, ob die Position der aktuellen Instanz in der Sortierreihenfolge vor, nach oder mit einem zweiten Objekt desselben Typs ist.It requires that implementing types define a single method, CompareTo(Object), that indicates whether the position of the current instance in the sort order is before, after, or the same as a second object of the same type. Die Implementierung der IComparable -Instanz wird automatisch durch Methoden Array.Sort wie und ArrayList.Sortaufgerufen.The instance's IComparable implementation is called automatically by methods such as Array.Sort and ArrayList.Sort.

Die Implementierung CompareTo(Object) der-Methode muss eine Int32 zurückgeben, die einen von drei Werten hat, wie in der folgenden Tabelle dargestellt.The implementation of the CompareTo(Object) method must return an Int32 that has one of three values, as shown in the following table.

WertValue BedeutungMeaning
Kleiner als 0 (null)Less than zero Die aktuelle Instanz befindet sich vor dem Objekt, das CompareTo von der-Methode in der Sortierreihenfolge angegeben wird.The current instance precedes the object specified by the CompareTo method in the sort order.
ZeroZero Diese aktuelle Instanz tritt in der Sortierreihenfolge an der gleichen Position wie das Objekt auf CompareTo , das von der-Methode angegeben wird.This current instance occurs in the same position in the sort order as the object specified by the CompareTo method.
Größer als 0 (null)Greater than zero Diese aktuelle Instanz folgt dem-Objekt, das CompareTo von der-Methode in der Sortierreihenfolge angegeben wird.This current instance follows the object specified by the CompareTo method in the sort order.

Alle numerischen Typen ( Int32 z. b. und IComparable Double String) Charimplementieren, wie DateTimez. b. und.All numeric types (such as Int32 and Double) implement IComparable, as do String, Char, and DateTime. Benutzerdefinierte Typen sollten auch Ihre eigene Implementierung von IComparable bereitstellen, um das Sortieren oder Sortieren von Objektinstanzen zu ermöglichen.Custom types should also provide their own implementation of IComparable to enable object instances to be ordered or sorted.

## Methoden

 CompareTo(Object) CompareTo(Object) CompareTo(Object) CompareTo(Object) 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.Compares the current instance with another object of the same type and returns an integer that indicates whether the current instance precedes, follows, or occurs in the same position in the sort order as the other object.