List(Of T).LastIndexOf Method (T)
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Searches for the specified object and returns the zero-based index of the last occurrence within the entire List(Of T).
Assembly: mscorlib (in mscorlib.dll)
Parameters
- item
- Type: T
The object to locate in the List(Of T). The value can be Nothing for reference types.
Return Value
Type: System.Int32The zero-based index of the last occurrence of item within the entire the List(Of T), if found; otherwise, –1.
The List(Of T) is searched backward starting at the last element and ending at the first element.
This method determines equality using the default equality comparer EqualityComparer(Of T).Default for T, the type of values in the list.
This method performs a linear search; therefore, this method is an O(n) operation, where n is Count.
The following code example demonstrates all three overloads of the LastIndexOf method. A List(Of T) of strings is created, with one entry that appears twice, at index location 0 and index location 5. The LastIndexOf(T) method overload searches the entire list from the end, and finds the second occurrence of the string. The LastIndexOf(T, Int32) method overload is used to search the list backward beginning with index location 3 and continuing to the beginning of the list, so it finds the first occurrence of the string in the list. Finally, the LastIndexOf(T, Int32, Int32) method overload is used to search a range of four entries, beginning at index location 4 and extending backward (that is, it searches the items at locations 4, 3, 2, and 1); this search returns –1 because there are no instances of the search string in that range.
Imports System.Collections.Generic Public Class Example Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock) Dim dinosaurs As New List(Of String) dinosaurs.Add("Tyrannosaurus") dinosaurs.Add("Amargasaurus") dinosaurs.Add("Mamenchisaurus") dinosaurs.Add("Brachiosaurus") dinosaurs.Add("Deinonychus") dinosaurs.Add("Tyrannosaurus") dinosaurs.Add("Compsognathus") outputBlock.Text &= vbCrLf For Each dinosaur As String In dinosaurs outputBlock.Text &= dinosaur & vbCrLf Next outputBlock.Text &= String.Format(vbLf & _ "LastIndexOf(""Tyrannosaurus""): {0}", _ dinosaurs.LastIndexOf("Tyrannosaurus")) & vbCrLf outputBlock.Text &= String.Format(vbLf & _ "LastIndexOf(""Tyrannosaurus"", 3): {0}", _ dinosaurs.LastIndexOf("Tyrannosaurus", 3)) & vbCrLf outputBlock.Text &= String.Format(vbLf & _ "LastIndexOf(""Tyrannosaurus"", 4, 4): {0}", _ dinosaurs.LastIndexOf("Tyrannosaurus", 4, 4)) & vbCrLf End Sub End Class ' This code example produces the following output: ' 'Tyrannosaurus 'Amargasaurus 'Mamenchisaurus 'Brachiosaurus 'Deinonychus 'Tyrannosaurus 'Compsognathus ' 'LastIndexOf("Tyrannosaurus"): 5 ' 'LastIndexOf("Tyrannosaurus", 3): 0 ' 'LastIndexOf("Tyrannosaurus", 4, 4): -1