IStructuralComparable.CompareTo(Object, IComparer) Metodo

Definizione

Determina se l'oggetto raccolta corrente precede, è nella stessa posizione o segue un altro oggetto nell'ordinamento.Determines whether the current collection object precedes, occurs in the same position as, or follows another object in the sort order.

public:
 int CompareTo(System::Object ^ other, System::Collections::IComparer ^ comparer);
public int CompareTo (object other, System.Collections.IComparer comparer);
abstract member CompareTo : obj * System.Collections.IComparer -> int
Public Function CompareTo (other As Object, comparer As IComparer) As Integer

Parametri

other
Object

Oggetto da confrontare con l'istanza corrente.The object to compare with the current instance.

comparer
IComparer

Oggetto che confronta membri dell'oggetto raccolta corrente con i membri corrispondenti di other.An object that compares members of the current collection object with the corresponding members of other.

Restituisce

Integer con segno che indica la relazione dell'oggetto corrente con other nell'ordinamento:A signed integer that indicates the relationship of the current collection object to other in the sort order:
- Se minore di 0, l'istanza corrente precede other.- If less than 0, the current instance precedes other.
- Se 0, l'istanza corrente e other sono uguali.- If 0, the current instance and other are equal.
- Se maggiore di 0, l'istanza corrente segue other.- If greater than 0, the current instance follows other.

Valore restituitoReturn value DescrizioneDescription
-1-1 L'istanza corrente precede other.The current instance precedes other.
00 L'istanza corrente è uguale a other.The current instance and other are equal.
11 L'istanza corrente segue other.The current instance follows other.

Eccezioni

Questa istanza e other non sono dello stesso tipo.This instance and other are not the same type.

Esempi

Nell'esempio seguente viene creata una matrice di oggetti Tuple<T1,T2,T3,T4,T5,T6> che contiene i dati della popolazione per tre città statunitensi da 1960 a 2000.The following example creates an array of Tuple<T1,T2,T3,T4,T5,T6> objects that contains population data for three U.S. cities from 1960 to 2000. Il primo componente di sestupla è il nome della città.The sextuple's first component is the city name. I restanti cinque componenti rappresentano la popolazione a intervalli di dieci anni da 1960 a 2000.The remaining five components represent the population at ten-year intervals from 1960 to 2000.

La classe PopulationComparer fornisce un'implementazione di IComparer che consente l'ordinamento della matrice di sestuple in base a uno dei relativi componenti.The PopulationComparer class provides an IComparer implementation that allows the array of sextuples to be sorted by any one of its components. Vengono forniti due valori alla classe PopulationComparer nel relativo costruttore, ovvero la posizione del componente che definisce l'ordinamento e un valore Boolean che indica se gli oggetti tupla devono essere ordinati in ordine crescente o decrescente.Two values are provided to the PopulationComparer class in its constructor: the position of the component that defines the sort order, and a Boolean value that indicates whether the tuple objects should be sorted in ascending or descending order.

Nell'esempio vengono quindi visualizzati gli elementi nella matrice in ordine non ordinato, li ordina in base al terzo componente (la popolazione in 1970) e li Visualizza, quindi li ordina in base al sesto componente (la popolazione in 2000) e li Visualizza.The example then displays the elements in the array in unsorted order, sorts them by the third component (the population in 1970) and displays them, and then sorts them by the sixth component (the population in 2000) and displays them. Si noti che l'esempio non chiama direttamente l'implementazione del IStructuralComparable.CompareTo.Note that the example does not directly call the IStructuralComparable.CompareTo implementation. Il metodo viene chiamato in modo implicito dal metodo Sort(Array, IComparer) per ogni oggetto tupla nella matrice.The method is called implicitly by the Sort(Array, IComparer) method for each tuple object in the array.

using System;
using System.Collections;
using System.Collections.Generic;

public class PopulationComparer<T1, T2, T3, T4, T5, T6> : IComparer
{
   private int itemPosition;
   private int multiplier = -1;

   public PopulationComparer(int component) : this(component, true)
   { }

   public PopulationComparer(int component, bool descending)
   {
      if (! descending) multiplier = 1;

      if (component <= 0 || component > 6)
         throw new ArgumentException("The component argument is out of range.");

      itemPosition = component;
   }

   public int Compare(object x, object y)
   {
      var tX = x as Tuple<T1, T2, T3, T4, T5, T6>;
      if (tX == null)
      {
         return 0;
      }
      else
      {
         var tY = y as Tuple<T1, T2, T3, T4, T5, T6>;
         switch (itemPosition)
         {
            case 1:
               return Comparer<T1>.Default.Compare(tX.Item1, tY.Item1) * multiplier;
            case 2:
               return Comparer<T2>.Default.Compare(tX.Item2, tY.Item2) * multiplier;
            case 3:
               return Comparer<T3>.Default.Compare(tX.Item3, tY.Item3) * multiplier;
            case 4:
               return Comparer<T4>.Default.Compare(tX.Item4, tY.Item4) * multiplier;
            case 5:
               return Comparer<T5>.Default.Compare(tX.Item5, tY.Item5) * multiplier;
            case 6:
               return Comparer<T6>.Default.Compare(tX.Item6, tY.Item6) * multiplier;
            default:
               return Comparer<T1>.Default.Compare(tX.Item1, tY.Item1) * multiplier;
         }
      }
   }
}

public class Example
{
   public static void Main()
   {
      // Create array of sextuple with population data for three U.S.
      // cities, 1960-2000.
      Tuple<string, int, int, int, int, int>[] cities =
           { Tuple.Create("Los Angeles", 2479015, 2816061, 2966850, 3485398, 3694820),
             Tuple.Create("New York", 7781984, 7894862, 7071639, 7322564, 8008278),
             Tuple.Create("Chicago", 3550904, 3366957, 3005072, 2783726, 2896016) };

      // Display array in unsorted order.
      Console.WriteLine("In unsorted order:");
      foreach (var city in cities)
         Console.WriteLine(city.ToString());
      Console.WriteLine();

      Array.Sort(cities, new PopulationComparer<string, int, int, int, int, int>(3));

      // Display array in sorted order.
      Console.WriteLine("Sorted by population in 1970:");
      foreach (var city in cities)
         Console.WriteLine(city.ToString());
      Console.WriteLine();

      Array.Sort(cities, new PopulationComparer<string, int, int, int, int, int>(6));

      // Display array in sorted order.
      Console.WriteLine("Sorted by population in 2000:");
      foreach (var city in cities)
         Console.WriteLine(city.ToString());
   }
}
// The example displays the following output:
//    In unsorted order:
//    (Los Angeles, 2479015, 2816061, 2966850, 3485398, 3694820)
//    (New York, 7781984, 7894862, 7071639, 7322564, 8008278)
//    (Chicago, 3550904, 3366957, 3005072, 2783726, 2896016)
//    
//    Sorted by population in 1970:
//    (New York, 7781984, 7894862, 7071639, 7322564, 8008278)
//    (Chicago, 3550904, 3366957, 3005072, 2783726, 2896016)
//    (Los Angeles, 2479015, 2816061, 2966850, 3485398, 3694820)
//    
//    Sorted by population in 2000:
//    (New York, 7781984, 7894862, 7071639, 7322564, 8008278)
//    (Los Angeles, 2479015, 2816061, 2966850, 3485398, 3694820)
//    (Chicago, 3550904, 3366957, 3005072, 2783726, 2896016)
Imports System.Collections
Imports System.Collections.Generic

Public Class PopulationComparer(Of T1, T2, T3, T4, T5, T6) : Implements IComparer
   Private itemPosition As Integer
   Private multiplier As Integer = -1
      
   Public Sub New(component As Integer)
      Me.New(component, True)
   End Sub
   
   Public Sub New(component As Integer, descending As Boolean)
      If Not descending Then multiplier = 1
      
      If component <= 0 Or component > 6 Then 
         Throw New ArgumentException("The component argument is out of range.")
      End If
      itemPosition = component
   End Sub 
   
   Public Function Compare(x As Object, y As Object) As Integer _
                   Implements IComparer.Compare
 
      Dim tX = TryCast(x, Tuple(Of T1, T2, T3, T4, T5, T6))
      If tX Is Nothing Then
         Return 0
      Else
         Dim tY = DirectCast(y, Tuple(Of T1, T2, T3, T4, T5, T6))
         Select Case itemPosition
            Case 1
               Return Comparer(Of T1).Default.Compare(tX.Item1, tY.Item1) * multiplier
            Case 2
               Return Comparer(Of T2).Default.Compare(tX.Item2, tY.Item2) * multiplier
            Case 3
               Return Comparer(Of T3).Default.Compare(tX.Item3, tY.Item3) * multiplier
            Case 4
               Return Comparer(Of T4).Default.Compare(tX.Item4, tY.Item4) * multiplier
            Case 5
               Return Comparer(Of T5).Default.Compare(tX.Item5, tY.Item5) * multiplier
            Case 6
               Return Comparer(Of T6).Default.Compare(tX.Item6, tY.Item6) * multiplier
            ' This should never happen.
            Case Else
               Return 0
         End Select      
      End If
   End Function
End Class

Module Example
   Public Sub Main()
      ' Create array of sextuple with population data for three U.S. 
      ' cities, 1960-2000.
      Dim cities() = 
          { Tuple.Create("Los Angeles", 2479015, 2816061, 2966850, 3485398, 3694820),
            Tuple.Create("New York", 7781984, 7894862, 7071639, 7322564, 8008278),  
            Tuple.Create("Chicago", 3550904, 3366957, 3005072, 2783726, 2896016) } 
      
      ' Display array in unsorted order.
      Console.WriteLine("In unsorted order:")
      For Each city In cities
         Console.WriteLine(city.ToString())
      Next
      Console.WriteLine()
      
      Array.Sort(cities, New PopulationComparer(Of String, Integer, Integer, Integer, Integer, Integer)(3)) 
                           
      ' Display array in sorted order.
      Console.WriteLine("Sorted by population in 1970:")
      For Each city In cities
         Console.WriteLine(city.ToString())
      Next
      Console.WriteLine()
      
      Array.Sort(cities, New PopulationComparer(Of String, Integer, Integer, Integer, Integer, Integer)(6))
                           
      ' Display array in sorted order.
      Console.WriteLine("Sorted by population in 2000:")
      For Each city In cities
         Console.WriteLine(city.ToString())
      Next
   End Sub
End Module
' The example displays the following output:
'    In unsorted order:
'    (Los Angeles, 2479015, 2816061, 2966850, 3485398, 3694820)
'    (New York, 7781984, 7894862, 7071639, 7322564, 8008278)
'    (Chicago, 3550904, 3366957, 3005072, 2783726, 2896016)
'    
'    Sorted by population in 1970:
'    (New York, 7781984, 7894862, 7071639, 7322564, 8008278)
'    (Chicago, 3550904, 3366957, 3005072, 2783726, 2896016)
'    (Los Angeles, 2479015, 2816061, 2966850, 3485398, 3694820)
'    
'    Sorted by population in 2000:
'    (New York, 7781984, 7894862, 7071639, 7322564, 8008278)
'    (Los Angeles, 2479015, 2816061, 2966850, 3485398, 3694820)
'    (Chicago, 3550904, 3366957, 3005072, 2783726, 2896016)

Commenti

Il metodo CompareTo supporta il confronto strutturale personalizzato e l'ordinamento degli oggetti Array e Tuple.The CompareTo method supports custom structural comparison and sorting of array and tuple objects. Il metodo CompareTo chiama il metodo IComparer.Compare dell'oggetto comparer per confrontare singoli elementi della matrice o componenti di tupla, a partire dal primo elemento o componente.The CompareTo method calls the comparer object's IComparer.Compare method to compare individual array elements or tuple components, starting with the first element or component. Le singole chiamate a IComparer.Compare end e il metodo CompareTo restituiscono un valore quando viene soddisfatta una delle condizioni seguenti:The individual calls to IComparer.Compare end and the CompareTo method returns a value when one of the following conditions becomes true:

Si applica a

Vedi anche