SortedList.IndexOfKey(Object) Method
Definition
Important
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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 -> intPublic Overridable Function IndexOfKey (key As Object) As IntegerParameters
- key
- Object
The key to locate in the SortedList object.
Returns
The zero-based index of the key parameter, if key is found in the SortedList object; otherwise, -1.
Exceptions
key is null.
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.
