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List.LastIndexOf Method (T)

Searches for the specified object and returns the zero-based index of the last occurrence within the entire List.

Namespace: System.Collections.Generic
Assembly: mscorlib (in mscorlib.dll)

public:
int LastIndexOf (
	T item
)
public int LastIndexOf (
	T item
)
public function LastIndexOf (
	item : T
) : int
Not applicable.

Parameters

item

The object to locate in the List. The value can be a null reference (Nothing in Visual Basic) for reference types.

Return Value

The zero-based index of the last occurrence of item within the entire the List, if found; otherwise, –1.

The List is searched backward starting at the last element and ending at the first element.

This method determines equality using the default equality comparer EqualityComparer.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 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.

using namespace System;
using namespace System::Collections::Generic;

void main()
{
    List<String^>^ dinosaurs = gcnew List<String^>();

    dinosaurs->Add("Tyrannosaurus");
    dinosaurs->Add("Amargasaurus");
    dinosaurs->Add("Mamenchisaurus");
    dinosaurs->Add("Brachiosaurus");
    dinosaurs->Add("Deinonychus");
    dinosaurs->Add("Tyrannosaurus");
    dinosaurs->Add("Compsognathus");

    Console::WriteLine();
    for each(String^ dinosaur in dinosaurs )
    {
        Console::WriteLine(dinosaur);
    }

    Console::WriteLine("\nLastIndexOf(\"Tyrannosaurus\"): {0}", 
        dinosaurs->LastIndexOf("Tyrannosaurus"));

    Console::WriteLine("\nLastIndexOf(\"Tyrannosaurus\", 3): {0}", 
        dinosaurs->LastIndexOf("Tyrannosaurus", 3));

    Console::WriteLine("\nLastIndexOf(\"Tyrannosaurus\", 4, 4): {0}", 
        dinosaurs->LastIndexOf("Tyrannosaurus", 4, 4));
}

/* 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
 */

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

.NET Compact Framework

Supported in: 2.0

XNA Framework

Supported in: 1.0

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