System Namespace Array Class
Searches for the specified object and returns the index of the last occurrence within the section of the one-dimensional Array that contains the specified number of elements and ends at the specified index.
[ VB ]
<Serializable>
Overloads Public Shared Function LastIndexOf ( _
ByVal array As Array, _
ByVal value As Object, _
ByVal startIndex As Integer, _
ByVal count As Integer _
) As Integer
[ C# ]
[Serializable]
public static int LastIndexOf (
Array array,
object value,
int startIndex,
int count
);
[ C++ ]
[Serializable]
public: static int LastIndexOf (
Array* array,
Object* value,
int startIndex,
int count
);
[JScript ]
public Serializable
static function LastIndexOf (
array : Array,
value : Object,
startIndex : int,
count : int
) : int;
- array
- The one-dimensional Array to search.
- value
- The object to locate in array.
- startIndex
- The starting index of the backward search.
- count
- The number of elements in the section to search.
The index of the last occurrence of value within the section of array that contains the number of elements specified in count and ends at startIndex, if found; otherwise, the lower bound of the array - 1.
| Exception Type |
Condition |
| ArgumentNullException |
array is a null reference ( Nothing in Visual Basic ). |
| ArgumentOutOfRangeException |
startIndex is outside the range of valid indexes for array.
-or-
count is less than zero.
-or-
startIndex and count do not specify a valid section in array.
|
| RankException |
array is multidimensional. |
The one-dimensional Array is searched backward starting at startIndex and ending at startIndex- count + 1.
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.
The following code example shows how to determine the index of the last occurrence of a specified element in an array. Note that the LastIndexOf method is a backward search; therefore, count must be less than or equal to ( startIndex- the lower bound of the array + 1 ).
[ VB ]
Imports System
Imports Microsoft.VisualBasic
Public Class SamplesArray
Public Shared Sub Main ( )
' Creates and initializes a new Array with three elements of
' the same value.
Dim myArray As Array = Array.CreateInstance ( GetType ( 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.
Response.WriteLine ( "The Array contains the following values:" )
PrintIndexAndValues ( myArray )
' Searches for the last occurrence of the duplicated value.
Dim myString As String = "the"
Dim myIndex As Integer = Array.LastIndexOf ( myArray, myString )
Response.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 )
Response.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 )
Response.WriteLine ( "The last occurrence of ""{0}"" between index 10 " _
+ "and index 6 is at index {1}.", myString, myIndex )
End Sub
Public Shared Sub PrintIndexAndValues ( myArray As Array )
Dim i As Integer
For i = myArray.GetLowerBound ( 0 ) To myArray.GetUpperBound ( 0 )
Response.WriteLine ( ControlChars.Tab + "[{0}]:" + ControlChars.Tab _
+ "{1}", i, myArray.GetValue ( i ) )
Next i
End Sub
End Class
' 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 10 and index 6 is at index 10.
[ C# ]
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 ( "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.
Response.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 );
Response.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 );
Response.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 );
Response.WriteLine ( "The last occurrence of \"{0}\" between index 10 and index 6 is at index {1}.", myString, myIndex );
}
public static void PrintIndexAndValues ( Array myArray ) {
for ( int i = myArray.GetLowerBound ( 0 ); i <= myArray.GetUpperBound ( 0 ); i++ )
Response.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 10 and index 6 is at index 10.
*/
[JScript ]
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.
Response.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 );
Response.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 );
Response.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 );
Response.WriteLine ( "The last occurrence of \"{0}\" between index 10 and index 6 is at index {1}.", myString, myIndex );
function PrintIndexAndValues ( myArray : System.Array ) {
for ( var i : int = myArray.GetLowerBound ( 0 ); i <= myArray.GetUpperBound ( 0 ); i++ )
Response.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 10 and index 6 is at index 10.
*/
Array Members Array.LastIndexOf Overload List IndexOf
