IComparable<T> Interface

Définition

Définit une méthode de comparaison généralisée qu’un type valeur ou une classe implémente pour créer une méthode de comparaison propre au type et permettant d’ordonnancer ou de trier ses instances.Defines a generalized comparison method that a value type or class implements to create a type-specific comparison method for ordering or sorting its instances.

generic <typename T>
public interface class IComparable
public interface IComparable<in T>
type IComparable<'T> = interface
Public Interface IComparable(Of In T)

Paramètres de type

T

Type de l’objet à comparer.The type of object to compare.

Dérivé

Exemples

L’exemple suivant illustre l’implémentation de IComparable<T> pour un objet simple. TemperatureThe following example illustrates the implementation of IComparable<T> for a simple Temperature object. L’exemple crée une SortedList<TKey,TValue> collection de chaînes avec Temperature des clés d’objet et ajoute plusieurs paires de températures et de chaînes à la liste hors séquence.The example creates a SortedList<TKey,TValue> collection of strings with Temperature object keys, and adds several pairs of temperatures and strings to the list out of sequence. Dans l’appel à la Add méthode, la SortedList<TKey,TValue> collection utilise l' IComparable<T> implémentation pour trier les entrées de liste, qui sont ensuite affichées par ordre de température grandissante.In the call to the Add method, the SortedList<TKey,TValue> collection uses the IComparable<T> implementation to sort the list entries, which are then displayed in order of increasing temperature.

#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) == 1;
    }
    
    // Define the is less than operator.
    bool operator<  (Temperature^ other)
    {
       return CompareTo(other) == -1;
    }
    
       // 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) == 1;
    }
    
    // Define the is less than operator.
    public static bool operator <  (Temperature operand1, Temperature operand2)
    {
       return operand1.CompareTo(operand2) == -1;
    }

    // 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.
*/
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) = 1
    End Operator
    
    ' Define the is less than operator.
    Public Shared Operator <  (operand1 As Temperature, operand2 As Temperature) As Boolean
       Return operand1.CompareTo(operand2) = -1
    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.
'

Remarques

Cette interface est implémentée par les types dont les valeurs peuvent être triées ou triées et fournit une méthode de comparaison fortement typée pour classer les membres d’un objet de collection générique.This interface is implemented by types whose values can be ordered or sorted and provides a strongly typed comparison method for ordering members of a generic collection object. Par exemple, un nombre peut être supérieur à un second nombre et une chaîne peut apparaître par ordre alphabétique avant une autre.For example, one number can be larger than a second number, and one string can appear in alphabetical order before another. Elle nécessite que les types d’implémentation définissent CompareTo(T)une méthode unique,, qui indique si la position de l’instance actuelle dans l’ordre de tri est antérieure, postérieure ou identique à un deuxième objet du même type.It requires that implementing types define a single method, CompareTo(T), 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. En règle générale, la méthode n’est pas appelée directement à partir du code de développeur.Typically, the method is not called directly from developer code. Au lieu de cela, il est appelé automatiquement par List<T>.Sort() des Addméthodes telles que et.Instead, it is called automatically by methods such as List<T>.Sort() and Add.

En règle générale, les types IComparable<T> qui fournissent une implémentation IEquatable<T> implémentent également l’interface.Typically, types that provide an IComparable<T> implementation also implement the IEquatable<T> interface. L' IEquatable<T> interface définit la Equals méthode, qui détermine l’égalité des instances du type d’implémentation.The IEquatable<T> interface defines the Equals method, which determines the equality of instances of the implementing type.

L’implémentation de la CompareTo(T) méthode doit retourner un Int32 qui a l’une des trois valeurs, comme indiqué dans le tableau suivant.The implementation of the CompareTo(T) method must return an Int32 that has one of three values, as shown in the following table.

ValueValue SignificationMeaning
Inférieure à zéroLess than zero Cet objet précède l’objet spécifié par la CompareTo méthode dans l’ordre de tri.This object precedes the object specified by the CompareTo method in the sort order.
ZéroZero Cette instance actuelle se trouve à la même position dans l’ordre de tri que l’objet spécifié CompareTo par l’argument de la méthode.This current instance occurs in the same position in the sort order as the object specified by the CompareTo method argument.
Supérieure à zéroGreater than zero Cette instance actuelle suit l’objet spécifié par l' CompareTo argument de la méthode dans l’ordre de tri.This current instance follows the object specified by the CompareTo method argument in the sort order.

Tous les types numériques (tels Int32 que Doubleet) IComparable<T>implémentent, Stringcomme Charles actions DateTime, et.All numeric types (such as Int32 and Double) implement IComparable<T>, as do String, Char, and DateTime. Les types personnalisés doivent également fournir leur propre implémentation IComparable<T> de pour permettre aux instances d’objet d’être ordonnées ou triées.Custom types should also provide their own implementation of IComparable<T> to enable object instances to be ordered or sorted.

Notes pour les responsables de l’implémentation

Remplacez le paramètre de type de IComparable<T> l’interface par le type qui implémente cette interface.Replace the type parameter of the IComparable<T> interface with the type that is implementing this interface.

Si vous implémentez IComparable<T>, vous devez surcharger les opérateurs op_LessThanOrEqual , op_LessThan op_GreaterThan op_GreaterThanOrEqual, et pour retourner les valeurs qui CompareTo(T)sont cohérentes avec.If you implement IComparable<T>, you should overload the op_GreaterThan, op_GreaterThanOrEqual, op_LessThan, and op_LessThanOrEqual operators to return values that are consistent with CompareTo(T). En outre, vous devez également implémenter IEquatable<T>.In addition, you should also implement IEquatable<T>. Consultez l' IEquatable<T> article pour obtenir des informations complètes.See the IEquatable<T> article for complete information.

Méthodes

CompareTo(T)

Compare l'instance actuelle avec un autre objet du même type et retourne un entier qui indique si l'instance actuelle précède ou suit un autre objet ou se trouve à la même position dans l'ordre de tri.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.

S’applique à

Voir aussi