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Char.IsSurrogatePair Method (Char, Char)

Indicates whether the two specified Char objects form a surrogate pair.

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

'Declaration
Public Shared Function IsSurrogatePair ( _
	highSurrogate As Char, _
	lowSurrogate As Char _
) As Boolean

Parameters

highSurrogate
Type: System.Char

The character to evaluate as the high surrogate of a surrogate pair.

lowSurrogate
Type: System.Char

The character to evaluate as the low surrogate of a surrogate pair.

Return Value

Type: System.Boolean
true if the numeric value of the highSurrogate parameter ranges from U+D800 through U+DBFF, and the numeric value of the lowSurrogate parameter ranges from U+DC00 through U+DFFF; otherwise, false.

Ordinarily, a single character is represented by a single 16-bit Unicode code unit. UTF-16 encoding also supports surrogate pairs, which allow a single abstract character to be represented by two 16-bit 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 points 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 

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

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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