Article
11/18/2011

String.LastIndexOfAny Method (array<Char[], Int32)

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Updated: October 2010

Reports the zero-based index position of the last occurrence in this instance of one or more characters specified in a Unicode array. The search starts at a specified character position.

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

Syntax

'Declaration
Public Function LastIndexOfAny ( _
    anyOf As Char(), _
    startIndex As Integer _
) As Integer

public int LastIndexOfAny(
    char[] anyOf,
    int startIndex
)

Parameters

anyOf
Type: array<System.Char[]
A Unicode character array containing one or more characters to seek.

startIndex
Type: System.Int32
The search starting position.

Return Value

Type: System.Int32
The index position of the last occurrence in this instance where any character in anyOf was found; otherwise, -1 if no character in anyOf was found or if the current instance equals String.Empty.

Exceptions

Exception	Condition
ArgumentNullException	anyOf is nulla null reference (Nothing in Visual Basic).
ArgumentOutOfRangeException	The current instance does not equal String.Empty and startIndex specifies a position not within this instance.

Remarks

Index numbering starts from zero.

This method begins searching at the startIndex character position of this instance and proceeds backward toward the beginning until either a character in anyOf is found or the first character position has been examined. 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 values are the same. To perform a culture-sensitive search, use the CompareInfo.LastIndexOf 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 the last occurrence of any character in the string "is" within a substring of another string.

' Sample for String.LastIndexOfAny(Char[], Int32)
 _

Class Example

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      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 target As String = "is"
      Dim anyOf As Char() = target.ToCharArray()

      start = (str.Length - 1) / 2
      outputBlock.Text += String.Format("The last character occurrence  from position {0} to 0.", start) & vbCrLf
      outputBlock.Text += String.Format("{1}{0}{2}{0}{3}{0}", Environment.NewLine, br1, br2, str) & vbCrLf
      outputBlock.Text += String.Format("A character in '{0}' occurs at position: ", target)

      at = str.LastIndexOfAny(anyOf, start)
      If at > -1 Then
         outputBlock.Text &= at
      Else
         outputBlock.Text &= "(not found)"
      End If
      outputBlock.Text += String.Format("{0}{0}{0}", Environment.NewLine)
   End Sub 'Main
End Class 'Sample
'
'This example produces the following results:
'The last character occurrence  from position 33 to 0.
'0----+----1----+----2----+----3----+----4----+----5----+----6----+-
'0123456789012345678901234567890123456789012345678901234567890123456
'Now is the time for all good men to come to the aid of their party.
'
'A character in 'is' occurs at position: 12
'
'
'

// Sample for String.LastIndexOfAny(Char[], Int32)
using System;

class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {

      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;
      string target = "is";
      char[] anyOf = target.ToCharArray();

      start = (str.Length - 1) / 2;
      outputBlock.Text += String.Format("The last character occurrence  from position {0} to 0.", start) + "\n";
      outputBlock.Text += String.Format("{1}{0}{2}{0}{3}{0}", Environment.NewLine, br1, br2, str) + "\n";
      outputBlock.Text += String.Format("A character in '{0}' occurs at position: ", target);

      at = str.LastIndexOfAny(anyOf, start);
      if (at > -1)
         outputBlock.Text += at;
      else
         outputBlock.Text += "(not found)";
      outputBlock.Text += String.Format("{0}{0}{0}", Environment.NewLine);
   }
}
/*
This example produces the following results:
The last character occurrence  from position 33 to 0.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

A character in 'is' occurs at position: 12


*/

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Change History

Date	History	Reason
October 2010	Noted that an exception is not thrown for an empty string if the index parameter is invalid.	Content bug fix.

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