IComparer.Compare(Object, Object) 方法

定義

命名空間:

System.Collections

組件:

System.Runtime.dll

比較兩個物件並傳回值，指出其中一個物件為小於、等於或大於另一個物件。

public:
 int Compare(System::Object ^ x, System::Object ^ y);

public int Compare (object? x, object? y);

abstract member Compare : obj * obj -> int

Public Function Compare (x As Object, y As Object) As Integer

參數

x

Object

要比較的第一個物件。

y

Object

要比較的第二個物件。

傳回

Int32

帶正負號的整數，表示 x 和 y 的相對值：
- 如果小於 0，x 小於 y。
- 如果為 0，x 等於 y。
- 如果大於 0，x 大於 y。

例外狀況

ArgumentException

x 和 y 都不實作 IComparable 介面。

-或-

x 和 y 是不同的型別，而且二者都不能處理與另外一方的比較。

範例

下列範例會 IComparer 使用 介面來排序字串陣列。 在此範例中 Compare ，會使用 CaseInsensitiveComparer 類別來實作 方法，以反轉數位內容的順序。

using System;
using System.Collections;

public class Example
{
   public class ReverserClass : IComparer
   {
      // Call CaseInsensitiveComparer.Compare with the parameters reversed.
      int IComparer.Compare(Object x, Object y)
      {
          return ((new CaseInsensitiveComparer()).Compare(y, x));
      }
   }

   public static void Main()
   {
      // Initialize a string array.
      string[] words = { "The", "quick", "brown", "fox", "jumps", "over",
                         "the", "lazy", "dog" };

      // Display the array values.
      Console.WriteLine("The array initially contains the following values:" );
      PrintIndexAndValues(words);

      // Sort the array values using the default comparer.
      Array.Sort(words);
      Console.WriteLine("After sorting with the default comparer:" );
      PrintIndexAndValues(words);

      // Sort the array values using the reverse case-insensitive comparer.
      Array.Sort(words, new ReverserClass());
      Console.WriteLine("After sorting with the reverse case-insensitive comparer:");
      PrintIndexAndValues(words);
   }

   public static void PrintIndexAndValues(IEnumerable list)
   {
      int i = 0;
      foreach (var item in list )
         Console.WriteLine($"   [{i++}]:  {item}");

      Console.WriteLine();
   }
}
// The example displays the following output:
//       The array initially contains the following values:
//          [0]:  The
//          [1]:  quick
//          [2]:  brown
//          [3]:  fox
//          [4]:  jumps
//          [5]:  over
//          [6]:  the
//          [7]:  lazy
//          [8]:  dog
//
//       After sorting with the default comparer:
//          [0]:  brown
//          [1]:  dog
//          [2]:  fox
//          [3]:  jumps
//          [4]:  lazy
//          [5]:  over
//          [6]:  quick
//          [7]:  the
//          [8]:  The
//
//       After sorting with the reverse case-insensitive comparer:
//          [0]:  the
//          [1]:  The
//          [2]:  quick
//          [3]:  over
//          [4]:  lazy
//          [5]:  jumps
//          [6]:  fox
//          [7]:  dog
//          [8]:  brown

Imports System.Collections

Public Class Example
   Public Class ReverserClass : Implements IComparer
      ' Call CaseInsensitiveComparer.Compare with the parameters reversed.
      Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer _
             Implements IComparer.Compare
         Return New CaseInsensitiveComparer().Compare(y, x)
      End Function 
   End Class

   Public Shared Sub Main()
      ' Initialize a string array.
      Dim words() As String = { "The", "quick", "brown", "fox", "jumps", "over",
                         "the", "lazy", "dog" }

      ' Display the array values.
      Console.WriteLine("The array initially contains the following values:")
      PrintIndexAndValues(words)

      ' Sort the array values of the ArrayList using the default comparer.
      Array.Sort(words)
      Console.WriteLine("After sorting with the default comparer:")
      PrintIndexAndValues(words)

      ' Sort the array values using the reverse case-insensitive comparer.
      Array.Sort(words, new ReverserClass())
      Console.WriteLine("After sorting with the reverse case-insensitive comparer:")
      PrintIndexAndValues(words)
   End Sub 

   Public Shared Sub PrintIndexAndValues(list As IEnumerable)
      Dim i As Integer = 0
      For Each item In  list
         Console.WriteLine($"   [{i}]:  {item}")
         i += 1
      Next
      Console.WriteLine()
   End Sub 
End Class
' The example displays the following output:
'       The array initially contains the following values:
'          [0]:  The
'          [1]:  quick
'          [2]:  brown
'          [3]:  fox
'          [4]:  jumps
'          [5]:  over
'          [6]:  the
'          [7]:  lazy
'          [8]:  dog
'       
'       After sorting with the default comparer:
'          [0]:  brown
'          [1]:  dog
'          [2]:  fox
'          [3]:  jumps
'          [4]:  lazy
'          [5]:  over
'          [6]:  quick
'          [7]:  the
'          [8]:  The
'       
'       After sorting with the reverse case-insensitive comparer:
'          [0]:  the
'          [1]:  The
'          [2]:  quick
'          [3]:  over
'          [4]:  lazy
'          [5]:  jumps
'          [6]:  fox
'          [7]:  dog
'          [8]:  brown

備註

慣用的實作是使用 CompareTo 其中一個參數的方法。

null使用 時，允許與任何類型進行比較，而且在使用 時IComparable不會產生例外狀況。 排序時， null 會被視為小於任何其他物件。

另請參閱

• IComparable
• CurrentCulture
• CompareInfo
• CultureInfo