IComparable IComparable IComparable IComparable Interface

定义

定义由值类型或类实现的特定于类型的通用比较方法,旨在对其实例进行排序。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
派生
属性

示例

下面的示例演示了的IComparable实现和必需CompareTo的方法。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;
      temperatures->Add(temp);
   }

   // 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;
         temperatures.Add(temp);   
      }

      // 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
         temperatures.Add(temp)   
      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

注解

此接口由其值可以排序或排序的类型实现。This interface is implemented by types whose values can be ordered or sorted. 它要求实现类型定义一个方法, CompareTo(Object)该方法指示当前实例在排序顺序中的位置是在同一类型的第二个对象之前、之后还是与其相同。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. 实例的IComparable实现由方法Array.Sort (如和ArrayList.Sort) 自动调用。The instance's IComparable implementation is called automatically by methods such as Array.Sort and ArrayList.Sort.

CompareTo(Object)方法的实现必须Int32返回具有以下三个值之一的, 如下表所示。The implementation of the CompareTo(Object) method must return an Int32 that has one of three values, as shown in the following table.

Value 含义Meaning
小于零Less than zero 当前实例在排序顺序中位于CompareTo方法所指定的对象之前。The current instance precedes the object specified by the CompareTo method in the sort order.
Zero 此当前实例与CompareTo方法所指定的对象在排序顺序中出现的位置相同。This current instance occurs in the same position in the sort order as the object specified by the CompareTo method.
大于零Greater than zero 此当前实例在排序顺序中跟随CompareTo方法所指定的对象。This current instance follows the object specified by the CompareTo method in the sort order.

所有Int32数值类型 (例如和IComparable Double DateTime) 均实现, 如String、和。 CharAll numeric types (such as Int32 and Double) implement IComparable, as do String, Char, and DateTime. 自定义类型还应提供自己的实现IComparable来启用对象实例的排序或排序。Custom types should also provide their own implementation of IComparable to enable object instances to be ordered or sorted.

方法

CompareTo(Object) CompareTo(Object) CompareTo(Object) CompareTo(Object)

将当前实例与同一类型的另一个对象进行比较,并返回一个整数,该整数指示当前实例在排序顺序中的位置是位于另一个对象之前、之后还是与其位置相同。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.

适用于