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String.IndexOf Method (Char, Int32)

Reports the zero-based index of the first occurrence of the specified Unicode character in this string. The search starts at a specified character position.

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

'Declaration
Public Function IndexOf ( _
	value As Char, _
	startIndex As Integer _
) As Integer

Parameters

value
Type: System.Char
A Unicode character to seek.
startIndex
Type: System.Int32
The search starting position.

Return Value

Type: System.Int32
The zero-based index position of value if that character is found, or -1 if it is not.

ExceptionCondition
ArgumentOutOfRangeException

startIndex is less than zero or greater than the length of this string instance.

Index numbering starts from zero. startIndex can range from 0 to one less than the length of the string instance.

The search ranges from startIndex to the end of the string.

The search for value 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.IndexOf 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 demonstrates the IndexOf method.


' Sample for String.IndexOf(Char, Int32)

Module Example
   Public 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

      outputBlock.Text &= vbCrLf
      outputBlock.Text &= String.Format("All occurrences of 't' from position 0 to {0}.", str.Length - 1) & vbCrLf
      outputBlock.Text &= String.Format("{1}{0}{2}{0}{3}{0}", vbCrLf, br1, br2, str) & vbCrLf
      outputBlock.Text &= "The letter 't' occurs at position(s): "

      at = 0
      start = 0
      While start < str.Length AndAlso at > -1
         at = str.IndexOf("t"c, start)
         If at = -1 Then
            Exit While
         End If
         outputBlock.Text &= String.Format("{0} ", at)
         start = at + 1
      End While
      outputBlock.Text &= vbCrLf
   End Sub
End Module
'
'This example produces the following results:
'
'All occurrences of 't' from position 0 to 66.
'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): 7 11 33 41 44 55 64
'
'


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.

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