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String.LastIndexOfAny Method (Char(), Int32, Int32)

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 and examines a specified number of character positions.

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

'Declaration
<SecuritySafeCriticalAttribute> _
Public Function LastIndexOfAny ( _
	anyOf As Char(), _
	startIndex As Integer, _
	count As Integer _
) As Integer

Parameters

anyOf
Type: System.Char()
A Unicode character array containing one or more characters to seek.
startIndex
Type: System.Int32
The search starting position.
count
Type: System.Int32
The number of character positions to examine.

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.

ExceptionCondition
ArgumentNullException

anyOf is Nothing.

ArgumentOutOfRangeException

The current instance does not equal String.Empty, and count or startIndex is negative.

-or-

The current instance does not equal String.Empty and startIndex minus count specifies a position that is not within this instance.

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 count character positions have 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.

The following code example finds the index of the last occurrence of any character in the string "aid" within a substring of another string.


' Sample for String.LastIndexOfAny(Char[], Int32, 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 count As Integer
      Dim target As String = "aid"
      Dim anyOf As Char() = target.ToCharArray()

      start = (str.Length - 1) * 2 / 3
      count = (str.Length - 1) / 3
      outputBlock.Text += String.Format("The last character occurrence from position {0} for {1} characters.", start, count) & 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, count)
      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 44 for 22 characters.
'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 'aid' occurs at position: 27
'


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

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

Date

History

Reason

October 2010

Noted that an exception is not thrown for an empty string if the index or length parameter is invalid.

Content bug fix.

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