.NET Framework Class Library
StringLastIndexOf Method (Char, Int32, Int32)

Reports the zero-based index position of the last occurrence of the specified Unicode character in a substring within this instance. The search starts at a specified character position and proceeds backward toward the beginning of the string for a specified number of character positions.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)
Syntax
Public Function LastIndexOf ( _
	value As [%$TOPIC/ms131439_en-us_VS_110_1_0_0_0_0%], _
	startIndex As [%$TOPIC/ms131439_en-us_VS_110_1_0_0_0_1%], _
	count As [%$TOPIC/ms131439_en-us_VS_110_1_0_0_0_2%] _
) As [%$TOPIC/ms131439_en-us_VS_110_1_0_0_0_3%]
public [%$TOPIC/ms131439_en-us_VS_110_1_0_1_0_0%] LastIndexOf(
	[%$TOPIC/ms131439_en-us_VS_110_1_0_1_0_1%] value,
	[%$TOPIC/ms131439_en-us_VS_110_1_0_1_0_2%] startIndex,
	[%$TOPIC/ms131439_en-us_VS_110_1_0_1_0_3%] count
)
public:
[%$TOPIC/ms131439_en-us_VS_110_1_0_2_0_0%] LastIndexOf(
	[%$TOPIC/ms131439_en-us_VS_110_1_0_2_0_1%] value, 
	[%$TOPIC/ms131439_en-us_VS_110_1_0_2_0_2%] startIndex, 
	[%$TOPIC/ms131439_en-us_VS_110_1_0_2_0_3%] count
)
member LastIndexOf : 
        value:[%$TOPIC/ms131439_en-us_VS_110_1_0_3_0_0%] * 
        startIndex:[%$TOPIC/ms131439_en-us_VS_110_1_0_3_0_1%] * 
        count:[%$TOPIC/ms131439_en-us_VS_110_1_0_3_0_2%] -> [%$TOPIC/ms131439_en-us_VS_110_1_0_3_0_3%]

Parameters

value
Type: SystemChar

The Unicode character to seek.

startIndex
Type: SystemInt32

The starting position of the search. The search proceeds from startIndex toward the beginning of this instance.

count
Type: SystemInt32

The number of character positions to examine.

Return Value

Type: SystemInt32
The zero-based index position of value if that character is found, or -1 if it is not found or if the current instance equals StringEmpty.
Exceptions
ExceptionCondition
ArgumentOutOfRangeException

The current instance does not equal StringEmpty, and startIndex is less than zero or greater than or equal to the length of this instance.

-or-

The current instance does not equal StringEmpty, and startIndex - count + 1 is less than zero.

Remarks

Index numbering starts from zero. That is, the first character in the string is at index zero and the last is at Length - 1.

This method begins searching at the startIndex character position and proceeds backward toward the beginning of this instance until either value is found or count character positions have been examined. For example, if startIndex is Length - 1, the method searches backward count characters from the last character in the string. The search is case-sensitive.

This method performs an ordinal (culture-insensitive) search, where a character is considered equivalent to another character only if their Unicode scalar value are the same. To perform a culture-sensitive search, use the CompareInfoLastIndexOf method, where a Unicode scalar value representing a precomposed character, such as the ligature "Æ" (U+00C6), might be considered equivalent to any occurrence of the character's components in the correct sequence, such as "AE" (U+0041, U+0045), depending on the culture.

Examples

The following example finds the index of all occurrences of a character in a substring, working from the end of the substring to the start of the substring.

' Sample for String.LastIndexOf(Char, Int32, Int32) 
Imports System
 _

Class Sample

   Public Shared Sub Main()

      Dim br1 As String = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-" 
      Dim br2 As String = "0123456789012345678901234567890123456789012345678901234567890123456" 
      Dim str As String = "Now is the time for all good men to come to the aid of their party." 
      Dim start As Integer 
      Dim at As Integer 
      Dim count As Integer 
      Dim [end] As Integer

      start = str.Length - 1
      [end] = start / 2 - 1
      Console.WriteLine("All occurrences of 't' from position {0} to {1}.", start, [end])
      Console.WriteLine("{1}{0}{2}{0}{3}{0}", Environment.NewLine, br1, br2, str)
      Console.Write("The letter 't' occurs at position(s): ")

      count = 0
      at = 0
      While start > - 1 And at > - 1
         count = start - [end] 'Count must be within the substring.
         at = str.LastIndexOf("t"c, start, count)
         If at > - 1 Then
            Console.Write("{0} ", at)
            start = at - 1
         End If 
      End While
      Console.Write("{0}{0}{0}", Environment.NewLine)
   End Sub 'Main 
End Class 'Sample
' 
'This example produces the following results: 
'All occurrences of 't' from position 66 to 32. 
'0----+----1----+----2----+----3----+----4----+----5----+----6----+- 
'0123456789012345678901234567890123456789012345678901234567890123456 
'Now is the time for all good men to come to the aid of their party. 
' 
'The letter 't' occurs at position(s): 64 55 44 41 33 
' 
'
// Sample for String.LastIndexOf(Char, Int32, Int32) 
using System;

class Sample {
    public static void Main() {

    string br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-";
    string br2 = "0123456789012345678901234567890123456789012345678901234567890123456";
    string str = "Now is the time for all good men to come to the aid of their party.";
    int start;
    int at;
    int count;
    int end;

    start = str.Length-1;
    end = start/2 - 1;
    Console.WriteLine("All occurrences of 't' from position {0} to {1}.", start, end);
    Console.WriteLine("{1}{0}{2}{0}{3}{0}", Environment.NewLine, br1, br2, str);
    Console.Write("The letter 't' occurs at position(s): ");

    count = 0;
    at = 0;
    while((start > -1) && (at > -1))
        {
        count = start - end; //Count must be within the substring.
        at = str.LastIndexOf('t', start, count);
        if (at > -1) 
            {
            Console.Write("{0} ", at);
            start = at - 1;
            }
        }
    Console.Write("{0}{0}{0}", Environment.NewLine);
    }
}
/*
This example produces the following results:
All occurrences of 't' from position 66 to 32.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The letter 't' occurs at position(s): 64 55 44 41 33


*/
// Sample for String::LastIndexOf(Char, Int32, Int32) 
using namespace System;
int main()
{
   String^ br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-";
   String^ br2 = "0123456789012345678901234567890123456789012345678901234567890123456";
   String^ str = "Now is the time for all good men to come to the aid of their party.";
   int start;
   int at;
   int count;
   int end;
   start = str->Length - 1;
   end = start / 2 - 1;
   Console::WriteLine( "All occurrences of 't' from position {0} to {1}.", start, end );
   Console::WriteLine( "\n{0}\n{1}\n{2}", br1, br2, str );
   Console::Write( "The letter 't' occurs at position(s): " );
   count = 0;
   at = 0;
   while ( (start > -1) && (at > -1) )
   {
      count = start - end; //Count must be within the substring.
      at = str->LastIndexOf( 't', start, count );
      if ( at > -1 )
      {
         Console::Write( " {0} ", at );
         start = at - 1;
      }
   }
}

/*
This example produces the following results:
All occurrences of 't' from position 66 to 32.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The letter 't' occurs at position(s): 64 55 44 41 33


*/
Version Information

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8
Platforms

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.