ArrayList.LastIndexOf Method (Object)
Searches for the specified Object and returns the zero-based index of the last occurrence within the entire ArrayList.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- value
-
Type:
System.Object
The Object to locate in the ArrayList. The value can be null.
Return Value
Type: System.Int32The zero-based index of the last occurrence of value within the entire the ArrayList, if found; otherwise, -1.
The ArrayList is searched backward starting at the last element and ending at the first element.
This method performs a linear search; therefore, this method is an O(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.
The following code example shows how to determine the index of the last occurrence of a specified element.
Imports System Imports System.Collections Imports Microsoft.VisualBasic Public Class SamplesArrayList Public Shared Sub Main() ' Creates and initializes a new ArrayList with three elements of the same value. Dim myAL As New ArrayList() myAL.Add("the") myAL.Add("quick") myAL.Add("brown") myAL.Add("fox") myAL.Add("jumps") myAL.Add("over") myAL.Add("the") myAL.Add("lazy") myAL.Add("dog") myAL.Add("in") myAL.Add("the") myAL.Add("barn") ' Displays the values of the ArrayList. Console.WriteLine("The ArrayList contains the following values:") PrintIndexAndValues(myAL) ' Searches for the last occurrence of the duplicated value. Dim myString As [String] = "the" Dim myIndex As Integer = myAL.LastIndexOf(myString) Console.WriteLine("The last occurrence of ""{0}"" is at index {1}.", myString, myIndex) ' Searches for the last occurrence of the duplicated value in the first section of the ArrayList. myIndex = myAL.LastIndexOf(myString, 8) Console.WriteLine("The last occurrence of ""{0}"" between the start and index 8 is at index {1}.", myString, myIndex) ' Searches for the last occurrence of the duplicated value in a section of the ArrayList. Note that the start index is greater than the end index because the search is done backward. myIndex = myAL.LastIndexOf(myString, 10, 6) Console.WriteLine("The last occurrence of ""{0}"" between index 10 and index 5 is at index {1}.", myString, myIndex) End Sub 'Main Public Shared Sub PrintIndexAndValues(myList As IEnumerable) Dim i as Integer Dim obj As [Object] For Each obj In myList Console.WriteLine(" [{0}]: {1}", i, obj) i = i + 1 Next obj Console.WriteLine() End Sub 'PrintIndexAndValues End Class 'SamplesArrayList ' This code produces the following output. ' ' The ArrayList contains the following values: ' [0]: the ' [1]: quick ' [2]: brown ' [3]: fox ' [4]: jumps ' [5]: over ' [6]: the ' [7]: lazy ' [8]: dog ' [9]: in ' [10]: the ' [11]: barn ' ' The last occurrence of "the" is at index 10. ' The last occurrence of "the" between the start and index 8 is at index 6. ' The last occurrence of "the" between index 10 and index 5 is at index 10.
Available since 10
.NET Framework
Available since 1.1