SortedList.IndexOfKey(Object) Method

Reference

Definition

Namespace:: System.Collections

Assemblies:: mscorlib.dll, System.Collections.NonGeneric.dll

Assemblies:: netstandard.dll, System.Collections.NonGeneric.dll

Assembly:: System.Collections.NonGeneric.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Source:: SortedList.cs

Source:: SortedList.cs

Source:: SortedList.cs

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Returns the zero-based index of the specified key in a SortedList object.

public:
 virtual int IndexOfKey(System::Object ^ key);

public virtual int IndexOfKey(object key);

abstract member IndexOfKey : obj -> int
override this.IndexOfKey : obj -> int

Public Overridable Function IndexOfKey (key As Object) As Integer

Parameters

key: Object

The key to locate in the SortedList object.

Returns

Int32

The zero-based index of the key parameter, if key is found in the SortedList object; otherwise, -1.

Exceptions

ArgumentNullException

key is null.

InvalidOperationException

The comparer throws an exception.

Examples

The following code example shows how to determine the index of a key or a value in a SortedList object.

#using <system.dll>

using namespace System;
using namespace System::Collections;
void PrintIndexAndKeysAndValues( SortedList^ myList )
{
   Console::WriteLine( "\t-INDEX-\t-KEY-\t-VALUE-" );
   for ( int i = 0; i < myList->Count; i++ )
   {
      Console::WriteLine( "\t[{0}]:\t{1}\t{2}", i, myList->GetKey( i ), myList->GetByIndex( i ) );

   }
   Console::WriteLine();
}

int main()
{
   
   // Creates and initializes a new SortedList.
   SortedList^ mySL = gcnew SortedList;
   mySL->Add( 1, "one" );
   mySL->Add( 3, "three" );
   mySL->Add( 2, "two" );
   mySL->Add( 4, "four" );
   mySL->Add( 0, "zero" );
   
   // Displays the values of the SortedList.
   Console::WriteLine( "The SortedList contains the following values:" );
   PrintIndexAndKeysAndValues( mySL );
   
   // Searches for a specific key.
   int myKey = 2;
   Console::WriteLine( "The key \"{0}\" is at index {1}.", myKey, mySL->IndexOfKey( myKey ) );
   
   // Searches for a specific value.
   String^ myValue = "three";
   Console::WriteLine( "The value \"{0}\" is at index {1}.", myValue, mySL->IndexOfValue( myValue ) );
}

/*
This code produces the following output.

The SortedList contains the following values:
        -INDEX- -KEY-   -VALUE-
        [0]:    0       zero
        [1]:    1       one
        [2]:    2       two
        [3]:    3       three
        [4]:    4       four

The key "2" is at index 2.
The value "three" is at index 3.
*/

using System;
using System.Collections;
public class SamplesSortedList  {

   public static void Main()  {

      // Creates and initializes a new SortedList.
      SortedList mySL = new SortedList();
      mySL.Add( 1, "one" );
      mySL.Add( 3, "three" );
      mySL.Add( 2, "two" );
      mySL.Add( 4, "four" );
      mySL.Add( 0, "zero" );

      // Displays the values of the SortedList.
      Console.WriteLine( "The SortedList contains the following values:" );
      PrintIndexAndKeysAndValues( mySL );

      // Searches for a specific key.
      int myKey = 2;
      Console.WriteLine( "The key \"{0}\" is at index {1}.", myKey, mySL.IndexOfKey( myKey ) );

      // Searches for a specific value.
      string myValue = "three";
      Console.WriteLine( "The value \"{0}\" is at index {1}.", myValue, mySL.IndexOfValue( myValue ) );
   }

   public static void PrintIndexAndKeysAndValues( SortedList myList )  {
      Console.WriteLine( "\t-INDEX-\t-KEY-\t-VALUE-" );
      for ( int i = 0; i < myList.Count; i++ )  {
         Console.WriteLine( "\t[{0}]:\t{1}\t{2}", i, myList.GetKey(i), myList.GetByIndex(i) );
      }
      Console.WriteLine();
   }
}
/*
This code produces the following output.

The SortedList contains the following values:
    -INDEX-    -KEY-    -VALUE-
    [0]:    0    zero
    [1]:    1    one
    [2]:    2    two
    [3]:    3    three
    [4]:    4    four

The key "2" is at index 2.
The value "three" is at index 3.
*/

Imports System.Collections

Public Class SamplesSortedList    
    
    Public Shared Sub Main()
        
        ' Creates and initializes a new SortedList.
        Dim mySL As New SortedList()
        mySL.Add(1, "one")
        mySL.Add(3, "three")
        mySL.Add(2, "two")
        mySL.Add(4, "four")
        mySL.Add(0, "zero")
        
        ' Displays the values of the SortedList.
        Console.WriteLine("The SortedList contains the " & _
           "following values:")
        PrintIndexAndKeysAndValues(mySL)
        
        ' Searches for a specific key.
        Dim myKey As Integer = 2
        Console.WriteLine("The key ""{0}"" is at index {1}.", myKey, _
           mySL.IndexOfKey(myKey))
        
        ' Searches for a specific value.
        Dim myValue As String = "three"
        Console.WriteLine("The value ""{0}"" is at index {1}.", myValue, _
           mySL.IndexOfValue(myValue))
    End Sub    
    
    
    Public Shared Sub PrintIndexAndKeysAndValues(myList As SortedList)
        Console.WriteLine(ControlChars.Tab & "-INDEX-" & ControlChars.Tab & _
           "-KEY-" & ControlChars.Tab & "-VALUE-")
        Dim i As Integer
        For i = 0 To myList.Count - 1
            Console.WriteLine(ControlChars.Tab & "[{0}]:" & ControlChars.Tab & _
               "{1}" & ControlChars.Tab & "{2}", i, myList.GetKey(i), _
               myList.GetByIndex(i))
        Next i
        Console.WriteLine()
    End Sub
End Class

' This code produces the following output.
' 
' The SortedList contains the following values:
'     -INDEX-    -KEY-    -VALUE-
'     [0]:    0    zero
'     [1]:    1    one
'     [2]:    2    two
'     [3]:    3    three
'     [4]:    4    four
'
' The key "2" is at index 2.
' The value "three" is at index 3.

Remarks

The elements of a SortedList object are sorted by the keys either according to a specific IComparer implementation specified when the SortedList is created, or according to the IComparable implementation provided by the keys themselves.

The index sequence is based on the sort sequence. When an element is added, it is inserted into SortedList in the correct sort order, and the indexing adjusts accordingly. When an element is removed, the indexing also adjusts accordingly. Therefore, the index of a specific key/value pair might change as elements are added or removed from the SortedList.

This method uses a binary search algorithm; therefore, this method is an O(log n) operation, where n is Count.

Starting with the .NET Framework 2.0, this method uses the collection's objects' Equals and CompareTo methods on item to determine whether item exists. In the earlier versions of the .NET Framework, this determination was made by using the Equals and CompareTo methods of the item parameter on the objects in the collection.

Applies to

Продукт	Версії
.NET	Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10
.NET Framework	1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard	2.0, 2.1
UWP	10.0

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