IComparable<T> Interfaccia

Definizione

generic <typename T>
public interface class IComparable

public interface IComparable<in T>

public interface IComparable<T>

type IComparable<'T> = interface

Public Interface IComparable(Of In T)

Public Interface IComparable(Of T)

Parametri di tipo

Derivato

Microsoft.Extensions.DependencyInjection.Specification.Fakes.ClassImplementingIComparable

System.Boolean

System.Byte

System.Char

System.DateOnly

Altro…

Esempio

Nell'esempio seguente viene illustrata l'implementazione di IComparable<T> per un oggetto semplice Temperature . L'esempio crea una SortedList<TKey,TValue> raccolta di stringhe con Temperature chiavi oggetto e aggiunge diverse coppie di temperature e stringhe all'elenco fuori sequenza. Nella chiamata al Add metodo, l'insieme SortedList<TKey,TValue> usa l'implementazione per ordinare le voci dell'elenco IComparable<T> , che vengono quindi visualizzate in ordine di aumento della temperatura.

#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.
'

Commenti

Questa interfaccia viene implementata dai tipi i cui valori possono essere ordinati o ordinati e fornisce un metodo di confronto fortemente tipizzato per ordinare i membri di un oggetto raccolta generico. Ad esempio, un numero può essere maggiore di un secondo numero e una stringa può essere visualizzata in ordine alfabetico prima di un'altra. È necessario che l'implementazione di tipi definiscano un singolo metodo, CompareTo(T), che indica se la posizione dell'istanza corrente nell'ordinamento è precedente, successiva o uguale a un secondo oggetto dello stesso tipo. In genere, il metodo non viene chiamato direttamente dal codice per sviluppatori. Viene invece chiamato automaticamente da metodi come List<T>.Sort() e Add.

In genere, i tipi che forniscono un'implementazione IComparable<T> implementano anche l'interfaccia IEquatable<T> . L'interfaccia IEquatable<T> definisce il Equals metodo, che determina l'uguaglianza delle istanze del tipo di implementazione.

L'implementazione del CompareTo(T) metodo deve restituire un oggetto Int32 con uno dei tre valori, come illustrato nella tabella seguente.

Tutti i tipi numerici (ad esempio Int32 e ) implementano IComparable<T>, come StringChar, e DateTimeDouble. I tipi personalizzati devono inoltre fornire la propria implementazione di per consentire l'ordinamento o l'ordinamento delle istanze di IComparable<T> oggetti.

Note per gli implementatori

Sostituire il parametro di tipo dell'interfaccia IComparable<T> con il tipo che sta implementando questa interfaccia.

Se si implementa IComparable<T>, è necessario eseguire l'overload degli operatori op_GreaterThan, op_GreaterThanOrEqual, op_LessThan e op_LessThanOrEqual per restituire valori coerenti con CompareTo(T). È inoltre necessario implementare IEquatable<T>. Per informazioni complete, vedere l'articolo IEquatable<T>.

Metodi

Si applica a

Vedi anche

• IComparable
• IEquatable<T>