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Array.LastIndexOf Method (Array, Object)

Searches for the specified object and returns the index of the last occurrence within the entire one-dimensional Array.

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

public static int LastIndexOf (
	Array array,
	Object value
)
public static int LastIndexOf (
	Array array, 
	Object value
)
public static function LastIndexOf (
	array : Array, 
	value : Object
) : int
Not applicable.

Parameters

array

The one-dimensional Array to search.

value

The object to locate in array.

Return Value

The index of the last occurrence of value within the entire array, if found; otherwise, the lower bound of the array minus 1.

Exception typeCondition

ArgumentNullException

array is a null reference (Nothing in Visual Basic).

RankException

array is multidimensional.

The one-dimensional Array is searched backward starting at the last element and ending at the first element.

The elements are compared to the specified value using the Object.Equals method. If the element type is a nonintrinsic (user-defined) type, the Equals implementation of that type is used.

Since most arrays will have a lower bound of zero, this method would generally return –1 when value is not found. In the rare case that the lower bound of the array is equal to Int32.MinValue and value is not found, this method returns Int32.MaxValue, which is System.Int32.MinValue - 1.

This method is an O(n) operation, where n is the Length of array.

In the .NET Framework version 2.0, this method uses the Equals and CompareTo methods of the Array to determine whether the Object specified by the value parameter exists. In the earlier versions of the .NET Framework, this determination was made by using the Equals and CompareTo methods of the valueObject itself.

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 in an array.

using System;
public class SamplesArray  {

   public static void Main()  {

      // Creates and initializes a new Array with three elements of the same value.
      Array myArray=Array.CreateInstance( typeof(String), 12 );
      myArray.SetValue( "the", 0 );
      myArray.SetValue( "quick", 1 );
      myArray.SetValue( "brown", 2 );
      myArray.SetValue( "fox", 3 );
      myArray.SetValue( "jumps", 4 );
      myArray.SetValue( "over", 5 );
      myArray.SetValue( "the", 6 );
      myArray.SetValue( "lazy", 7 );
      myArray.SetValue( "dog", 8 );
      myArray.SetValue( "in", 9 );
      myArray.SetValue( "the", 10 );
      myArray.SetValue( "barn", 11 );

      // Displays the values of the Array.
      Console.WriteLine( "The Array contains the following values:" );
      PrintIndexAndValues( myArray );

      // Searches for the last occurrence of the duplicated value.
      String myString = "the";
      int myIndex = Array.LastIndexOf( myArray, 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 Array.
      myIndex = Array.LastIndexOf( myArray, 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 Array.
      // Note that the start index is greater than the end index because the search is done backward.
      myIndex = Array.LastIndexOf( myArray, myString, 10, 6 );
      Console.WriteLine( "The last occurrence of \"{0}\" between index 5 and index 10 is at index {1}.", myString, myIndex );
   }


   public static void PrintIndexAndValues( Array myArray )  {
      for ( int i = myArray.GetLowerBound(0); i <= myArray.GetUpperBound(0); i++ )
         Console.WriteLine( "\t[{0}]:\t{1}", i, myArray.GetValue( i ) );
   }
}
/* 
This code produces the following output.

The Array 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 5 and index 10 is at index 10.
*/

import System.*;

public class SamplesArray
{
    public static void main(String[] args)
    {
        // Creates and initializes a new Array with three elements of 
        // the same value.
        Array myArray = Array.CreateInstance(String.class.ToType(), 12);
        myArray.SetValue("the", 0);
        myArray.SetValue("quick", 1);
        myArray.SetValue("brown", 2);
        myArray.SetValue("fox", 3);
        myArray.SetValue("jumps", 4);
        myArray.SetValue("over", 5);
        myArray.SetValue("the", 6);
        myArray.SetValue("lazy", 7);
        myArray.SetValue("dog", 8);
        myArray.SetValue("in", 9);
        myArray.SetValue("the", 10);
        myArray.SetValue("barn", 11);
        // Displays the values of the Array.
        Console.WriteLine("The Array contains the following values:");
        PrintIndexAndValues(myArray);
        // Searches for the last occurrence of the duplicated value.
        String myString = "the";
        int myIndex = Array.LastIndexOf(myArray, myString);
        Console.WriteLine("The last occurrence of \"{0}\" is at index {1}.",
            myString,(Int32)myIndex);
        // Searches for the last occurrence of the duplicated value in the first
        // section of the Array.
        myIndex = Array.LastIndexOf(myArray, myString, 8);
        Console.WriteLine("The last occurrence of \"{0}\" between the start"
            + " and index 8 is at index {1}.", myString, (Int32)myIndex);
        // Searches for the last occurrence of the duplicated value in a 
        // section of the Array.
        // Note that the start index is greater than the end index because the 
        // search is done backward.
        myIndex = Array.LastIndexOf(myArray, myString, 10, 6);
        Console.WriteLine("The last occurrence of \"{0}\" between index 5 and"
            + " index 10 is at index {1}.",myString,(Int32)myIndex);
    } //main

    public static void PrintIndexAndValues(Array myArray)
    {
        for (int i = myArray.GetLowerBound(0); i <= myArray.
            GetUpperBound(0); i++) {
            Console.WriteLine("\t[{0}]:\t{1}",(Int32)i,myArray.GetValue(i));
        }
    } //PrintIndexAndValues
} //SamplesArray 

 /* 
 This code produces the following output.
 
 The Array 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 5 and index 10 is at index 10.
 */

import System;

// Creates and initializes a new Array with three elements of the same value.
var myArray : System.Array= System.Array.CreateInstance( System.String, 12 );
myArray.SetValue( "the", 0 );
myArray.SetValue( "quick", 1 );
myArray.SetValue( "brown", 2 );
myArray.SetValue( "fox", 3 );
myArray.SetValue( "jumped", 4 );
myArray.SetValue( "over", 5 );
myArray.SetValue( "the", 6 );
myArray.SetValue( "lazy", 7 );
myArray.SetValue( "dog", 8 );
myArray.SetValue( "in", 9 );
myArray.SetValue( "the", 10 );
myArray.SetValue( "barn", 11 );

// Displays the values of the Array.
Console.WriteLine( "The Array contains the following values:" );
PrintIndexAndValues( myArray );

// Searches for the last occurrence of the duplicated value.
var myString : String = "the";
var myIndex : int = System.Array.LastIndexOf( myArray, 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 Array.
myIndex = System.Array.LastIndexOf( myArray, 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 Array. 
// Note that the start index is greater than the end index because the search is done backward.
myIndex = System.Array.LastIndexOf( myArray, myString, 10, 6 );
Console.WriteLine( "The last occurrence of \"{0}\" between index 5 and index 10 is at index {1}.", myString, myIndex );
 
 
function PrintIndexAndValues( myArray : System.Array )  {
   for ( var i : int = myArray.GetLowerBound(0); i <= myArray.GetUpperBound(0); i++ )
      Console.WriteLine( "\t[{0}]:\t{1}", i, myArray.GetValue( i ) );
}
 
 /* 
 This code produces the following output.
 
 The Array contains the following values:
     [0]:    the
     [1]:    quick
     [2]:    brown
     [3]:    fox
     [4]:    jumped
     [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 5 and index 10 is at index 10.
 */

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, 1.1, 1.0

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