String.LastIndexOfAny Method (array<Char[], Int32, 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 and examines a specified number of character positions.
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
<SecuritySafeCriticalAttribute> _
Public Function LastIndexOfAny ( _
anyOf As Char(), _
startIndex As Integer, _
count As Integer _
) As Integer
[SecuritySafeCriticalAttribute]
public int LastIndexOfAny(
char[] anyOf,
int startIndex,
int count
)
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.
- 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.
Exceptions
| Exception | Condition |
|---|---|
| ArgumentNullException | anyOf is nulla null reference (Nothing in Visual Basic). |
| 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. |
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 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.
Examples
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
'
// Sample for String.LastIndexOfAny(Char[], Int32, 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;
int count;
string target = "aid";
char[] anyOf = 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) + "\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, count);
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 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
*/
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.
See Also
Reference
Change History
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. |