Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
IsSurrogatePair Method (String, Int32)
Collapse the table of content
Expand the table of content

Char.IsSurrogatePair Method (String, Int32)

Indicates whether two adjacent Char objects at a specified position in a string form a surrogate pair.

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

'Declaration
Public Shared Function IsSurrogatePair ( _
	s As String, _
	index As Integer _
) As Boolean
'Usage
Dim s As String 
Dim index As Integer 
Dim returnValue As Boolean 

returnValue = Char.IsSurrogatePair(s, _
	index)

Parameters

s
Type: System.String

A string.

index
Type: System.Int32

A position within s.

Return Value

Type: System.Boolean
true if the s parameter and the index parameter specify a pair of adjacent characters, and the numeric value of the character at position index ranges from U+D800 through U+DBFF, and the numeric value of the character at position index+1 ranges from U+DC00 through U+DFFF; otherwise, false.

ExceptionCondition
ArgumentNullException

s is Nothing.

ArgumentOutOfRangeException

index is not a position within s.

Ordinarily, a single character is represented by a single UTF-16 code unit. UTF-16 encoding also supports surrogate pairs, which allow a single abstract character to be represented by two UTF-16 code units. The first code unit, whose value can range from U+D800 to U+DBFF, is the high surrogate. The second code unit, whose value can range from U+DC00 to U+DFFF, is the low surrogate. Individual surrogate code units have no interpretation of their own. For more information about surrogates and the Unicode Standard, see the Unicode home page.

The following code example demonstrates the IsHighSurrogate, IsLowSurrogate, and IsSurrogatePair methods.

' This example demonstrates the Char.IsLowSurrogate() method 
'                                    IsHighSurrogate() method 
'                                    IsSurrogatePair() method 
Imports System
Imports Microsoft.VisualBasic

Class Sample
   Public Shared Sub Main()
      Dim cHigh As Char = ChrW(&HD800)
      Dim cLow  As Char = ChrW(&HDC00)
      Dim s1 = New [String](New Char() {"a"c, ChrW(&HD800), ChrW(&HDC00), "z"c})
      Dim divider As String = [String].Concat(Environment.NewLine, _
                                              New [String]("-"c, 70), _
                                              Environment.NewLine)

      Console.WriteLine()
      Console.WriteLine("Hexadecimal code point of the character, cHigh: {0:X4}", AscW(cHigh))
      Console.WriteLine("Hexadecimal code point of the character, cLow:  {0:X4}", AscW(cLow))
      Console.WriteLine()
      Console.WriteLine("Characters in string, s1: 'a', high surrogate, low surrogate, 'z'")
      Console.WriteLine("Hexadecimal code points of the characters in string, s1: ")
      Dim i As Integer 
      For i = 0 To s1.Length - 1
         Console.WriteLine("s1({0}) = {1:X4} ", i, AscW(s1.Chars(i)))
      Next i
      Console.WriteLine(divider)

      Console.WriteLine("Is each of the following characters a high surrogate?")
      Console.WriteLine("A1) cLow?  - {0}", [Char].IsHighSurrogate(cLow))
      Console.WriteLine("A2) cHigh? - {0}", [Char].IsHighSurrogate(cHigh))
      Console.WriteLine("A3) s1(0)? - {0}", [Char].IsHighSurrogate(s1, 0))
      Console.WriteLine("A4) s1(1)? - {0}", [Char].IsHighSurrogate(s1, 1))
      Console.WriteLine(divider)

      Console.WriteLine("Is each of the following characters a low surrogate?")
      Console.WriteLine("B1) cLow?  - {0}", [Char].IsLowSurrogate(cLow))
      Console.WriteLine("B2) cHigh? - {0}", [Char].IsLowSurrogate(cHigh))
      Console.WriteLine("B3) s1(0)? - {0}", [Char].IsLowSurrogate(s1, 0))
      Console.WriteLine("B4) s1(2)? - {0}", [Char].IsLowSurrogate(s1, 2))
      Console.WriteLine(divider)

      Console.WriteLine("Is each of the following pairs of characters a surrogate pair?")
      Console.WriteLine("C1) cHigh and cLow?  - {0}", [Char].IsSurrogatePair(cHigh, cLow))
      Console.WriteLine("C2) s1(0) and s1(1)? - {0}", [Char].IsSurrogatePair(s1, 0))
      Console.WriteLine("C3) s1(1) and s1(2)? - {0}", [Char].IsSurrogatePair(s1, 1))
      Console.WriteLine("C4) s1(2) and s1(3)? - {0}", [Char].IsSurrogatePair(s1, 2))
      Console.WriteLine(divider)
   End Sub 'Main
End Class 'Sample

'This example produces the following results: 

'Hexadecimal code point of the character, cHigh: D800 
'Hexadecimal code point of the character, cLow:  DC00 

'Characters in string, s1: 'a', high surrogate, low surrogate, 'z' 
'Hexadecimal code points of the characters in string, s1: 
's1(0) = 0061 
's1(1) = D800 
's1(2) = DC00 
's1(3) = 007A 

'---------------------------------------------------------------------- 

'Is each of the following characters a high surrogate? 
'A1) cLow?  - False 
'A2) cHigh? - True 
'A3) s1(0)? - False 
'A4) s1(1)? - True 

'---------------------------------------------------------------------- 

'Is each of the following characters a low surrogate? 
'B1) cLow?  - True 
'B2) cHigh? - False 
'B3) s1(0)? - False 
'B4) s1(2)? - True 

'---------------------------------------------------------------------- 

'Is each of the following pairs of characters a surrogate pair? 
'C1) cHigh and cLow?  - True 
'C2) s1(0) and s1(1)? - False 
'C3) s1(1) and s1(2)? - True 
'C4) s1(2) and s1(3)? - False 

'---------------------------------------------------------------------- 
'

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0

.NET Compact Framework

Supported in: 3.5, 2.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Community Additions

ADD
Show:
© 2015 Microsoft