Array.LastIndexOf(T) Method (T, T, Int32, Int32)
Searches for the specified object and returns the index of the last occurrence within the range of elements in the Array that contains the specified number of elements and ends at the specified index.
Assembly: mscorlib (in mscorlib.dll)
static member LastIndexOf : array:'T * value:'T * startIndex:int * count:int -> int
The type of the elements of the array.
- Type: 
The one-dimensional, zero-based Array to search.
The object to locate in array.
- Type: System.Int32
The zero-based starting index of the backward search.
- Type: System.Int32
The number of elements in the section to search.
Return ValueType: System.Int32
The zero-based 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, –1.
The 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, the Equals implementation of that type is used.
This method is an O(n) operation, where n is count.
The following code example demonstrates all three generic overloads of the LastIndexOf method. An array of strings is created, with one entry that appears twice, at index location 0 and index location 5. The LastIndexOf(T)(T, T) method overload searches the entire array from the end, and finds the second occurrence of the string. The LastIndexOf(T)(T, T, Int32) method overload is used to search the array backward beginning with index location 3 and continuing to the beginning of the array, and finds the first occurrence of the string. Finally, the 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.
.NET FrameworkSupported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0
.NET Framework Client ProfileSupported in: 4, 3.5 SP1
Portable Class LibrarySupported in: Portable Class Library
.NET for Windows Store appsSupported in: Windows 8
Supported in: Windows Phone 8.1
Supported in: Windows Phone Silverlight 8.1
Supported in: Windows Phone Silverlight 8
Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.