LastIndexOf Method (Array, Object, Int32, Int32)

Array.LastIndexOf Method (Array, Object, Int32, Int32)

 

Searches for the specified object and returns the index of the last occurrence within the range of elements in the one-dimensional Array that contains the specified number of elements and ends at the specified index.

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

static member LastIndexOf : 
        array:Array *
        value:Object *
        startIndex:int *
        count:int -> int

Parameters

array
Type: System.Array

The one-dimensional Array to search.

value
Type: System.Object

The object to locate in array.

startIndex
Type: System.Int32

The starting index of the backward search.

count
Type: System.Int32

The number of elements in the section to search.

Return Value

Type: System.Int32

The index of the last occurrence of value within the range of elements in array that contains the number of elements specified in count and ends at startIndex, if found; otherwise, the lower bound of the array minus 1.

Exception Condition
ArgumentNullException

array is null.

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 minus count plus 1, if count is greater than 0.

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

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.

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 minus the lower bound of the array plus 1).

No code example is currently available or this language may not be supported.

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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