SortedList.ContainsKey Method

Determines whether the SortedList contains a specific key.

[Visual Basic]
Public Overridable Function ContainsKey( _
   ByVal key As Object _
) As Boolean
[C#]
public virtual bool ContainsKey(
 object key
);
[C++]
public: virtual bool ContainsKey(
 Object* key
);
[JScript]
public function ContainsKey(
   key : Object
) : Boolean;

Parameters

key

The key to locate in the SortedList.

Return Value

true if the SortedList contains an element with the specified key; otherwise, false.

Exceptions

Remarks

The elements of a SortedList 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.

This method uses a binary search algorithm; therefore, the average execution time is proportional to Log2 (n), where n is Count.

This method behaves exactly as Contains.

Example

[Visual Basic, C#, C++] The following example shows how to determine whether the SortedList contains a specific element.

[Visual Basic] 
Imports System
Imports System.Collections
Imports Microsoft.VisualBasic

Public Class SamplesSortedList    
    
    Public Shared Sub Main()
        
        ' Creates and initializes a new SortedList.
        Dim mySL As New SortedList()
        mySL.Add(2, "two")
        mySL.Add(4, "four")
        mySL.Add(1, "one")
        mySL.Add(3, "three")
        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
        Dim msg As String
        If mySL.ContainsKey(myKey) Then
            msg = "in the SortedList"
        Else
            msg = "NOT in the SortedList"
        End If
        Console.WriteLine("The key ""{0}"" is {1}.", myKey, msg)
        myKey = 6
        If mySL.ContainsKey(myKey) Then
            msg = "in the SortedList"
        Else
            msg = "NOT in the SortedList"
        End If
        Console.WriteLine("The key ""{0}"" is {1}.", myKey, msg)        
        ' Searches for a specific value.
        Dim myValue As String = "three"
        If mySL.ContainsValue(myValue) Then
            msg = "in the SortedList"
        Else
            msg = "NOT in the SortedList"
        End If
        Console.WriteLine("The value ""{0}"" is {1}.", myValue, msg)
        myValue = "nine"
        If mySL.ContainsValue(myValue) Then
            msg = "in the SortedList"
        Else
            msg = "NOT in the SortedList"
        End If
        Console.WriteLine("The value ""{0}"" is {1}.", myValue, msg)
    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 in the SortedList.
' The key "6" is NOT in the SortedList.
' The value "three" is in the SortedList.
' The value "nine" is NOT in the SortedList. 

[C#] 
using System;
using System.Collections;

public class SamplesSortedList  {

   public static void Main()  {

      // Creates and initializes a new SortedList.
      SortedList mySL = new SortedList();
      mySL.Add( 2, "two" );
      mySL.Add( 4, "four" );
      mySL.Add( 1, "one" );
      mySL.Add( 3, "three" );
      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 {1}.", myKey, mySL.ContainsKey( myKey ) ? "in the SortedList" : "NOT in the SortedList" );
      myKey = 6;
      Console.WriteLine( "The key \"{0}\" is {1}.", myKey, mySL.ContainsKey( myKey ) ? "in the SortedList" : "NOT in the SortedList" );

      // Searches for a specific value.
      String myValue = "three";
      Console.WriteLine( "The value \"{0}\" is {1}.", myValue, mySL.ContainsValue( myValue ) ? "in the SortedList" : "NOT in the SortedList" );
      myValue = "nine";
      Console.WriteLine( "The value \"{0}\" is {1}.", myValue, mySL.ContainsValue( myValue ) ? "in the SortedList" : "NOT in the SortedList" );
   }


   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 in the SortedList.
The key "6" is NOT in the SortedList.
The value "three" is in the SortedList.
The value "nine" is NOT in the SortedList.
*/ 

[C++] 
#using <mscorlib.dll>
#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}", __box(i), myList->GetKey(i), myList->GetByIndex(i) );
   }
   Console::WriteLine();
}

int main()  {

   // Creates and initializes a new SortedList.
   SortedList *mySL = new SortedList();
   mySL->Add( __box(2), S"two" );
   mySL->Add( __box(4), S"four" );
   mySL->Add( __box(1), S"one" );
   mySL->Add( __box(3), S"three" );
   mySL->Add( __box(0), S"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 {1}.", __box(myKey), mySL->ContainsKey( __box(myKey) ) ? S"in the SortedList" : S"NOT in the SortedList" );
   myKey = 6;
   Console::WriteLine( "The key \"{0}\" is {1}.", __box(myKey), mySL->ContainsKey( __box(myKey) ) ? S"in the SortedList" : S"NOT in the SortedList" );

   // Searches for a specific value.
   String *myValue = S"three";
   Console::WriteLine( "The value \"{0}\" is {1}.", myValue, mySL->ContainsValue( myValue ) ? S"in the SortedList" : S"NOT in the SortedList" );
   myValue = "nine";
   Console::WriteLine( "The value \"{0}\" is {1}.", myValue, mySL->ContainsValue( myValue ) ? S"in the SortedList" : S"NOT in the SortedList" );
} 

/* 
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 in the SortedList.
The key "6" is NOT in the SortedList.
The value "three" is in the SortedList.
The value "nine" is NOT in the SortedList.
*/ 

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

SortedList Class | SortedList Members | System.Collections Namespace | Contains | ContainsValue | IndexOfKey | Performing Culture-Insensitive String Operations in Collections