This documentation is archived and is not being maintained.

Char.IsLowSurrogate Method (String, Int32)

Indicates whether the Char object at the specified position in a string is a low surrogate.

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

public static bool IsLowSurrogate (
	string s,
	int index
)
public static boolean IsLowSurrogate (
	String s, 
	int index
)
public static function IsLowSurrogate (
	s : String, 
	index : int
) : boolean
Not applicable.

Parameters

s

A string.

index

A position within s.

Return Value

true if the numeric value of the specified character in the s parameter ranges from U+DC00 through U+DFFF; otherwise, false.

Exception typeCondition

ArgumentNullException

s is a null reference (Nothing in Visual Basic).

ArgumentOutOfRangeException

index is not a position within s.

The index parameter is zero-based.

In addition to representing single characters using a 16-bit code point, UTF-16 encoding allows abstract characters to be represented using two 16-bit code points, which is known as a surrogate pair. The second element in this pair is the low surrogate, and its code point can range from U+DC00 to U+DFFF. An individual surrogate has no interpretation of its own, but is meaningful only when used as part of a surrogate pair.

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

// This example demonstrates the Char.IsLowSurrogate() method
//                                    IsHighSurrogate() method
//                                    IsSurrogatePair() method
using System;

class Sample 
{
    public static void Main() 
    {
    char cHigh = '\uD800';
    char cLow  = '\uDC00';
    string s1  = new String(new char[] {'a', '\uD800', '\uDC00', 'z'});
    string divider = String.Concat( Environment.NewLine, new String('-', 70), 
                                    Environment.NewLine);

    Console.WriteLine();
    Console.WriteLine("Hexadecimal code point of the character, cHigh: {0:X4}", (int)cHigh);
    Console.WriteLine("Hexadecimal code point of the character, cLow:  {0:X4}", (int)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: ");
    for(int i = 0; i < s1.Length; i++)
        {
        Console.WriteLine("s1[{0}] = {1:X4} ", i, (int)s1[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);
    }
}
/*
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

----------------------------------------------------------------------

*/

// This example demonstrates the Char.IsLowSurrogate() method
// IsHighSurrogate() method
// sIsSurrogatePair() method
import System.*;

class Sample
{
    public static void main(String[] args)
    {
        char cHigh = '\uD800';
        char cLow = '\uDC00';
        String s1 = new String(new char[] { 'a', '\uD800', '\uDC00', 'z' });
        String divider = String.Concat(Environment.get_NewLine(), 
            new String('-', 70), Environment.get_NewLine());

        Console.WriteLine();
        Console.WriteLine("Hexadecimal code point of the character,"
            + " cHigh: {0:X4}", (Int32)cHigh);
        Console.WriteLine("Hexadecimal code point of the character,"
            + " cLow:  {0:X4}", (Int32)(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: ");
        for (int i = 0; i < s1.get_Length(); i++) {
            Console.WriteLine("s1[{0}] = {1:X4} ", (Int32)i, (Int32)s1.
                get_Chars(i));
        }
        Console.WriteLine(divider);
        Console.WriteLine("Is each of the following characters a high surrogate?");
        Console.WriteLine("A1) cLow?  - {0}", (System.Boolean)Char.
            IsHighSurrogate(cLow));
        Console.WriteLine("A2) cHigh? - {0}", (System.Boolean)Char.
            IsHighSurrogate(cHigh));
        Console.WriteLine("A3) s1[0]? - {0}", (System.Boolean)Char.
            IsHighSurrogate(s1, 0));
        Console.WriteLine("A4) s1[1]? - {0}", (System.Boolean)Char.
            IsHighSurrogate(s1, 1));
        Console.WriteLine(divider);

        Console.WriteLine("Is each of the following characters a low surrogate?");
        Console.WriteLine("B1) cLow?  - {0}", (System.Boolean)Char.
            IsLowSurrogate(cLow));
        Console.WriteLine("B2) cHigh? - {0}", (System.Boolean)Char.
            IsLowSurrogate(cHigh));
        Console.WriteLine("B3) s1[0]? - {0}", (System.Boolean)Char.
            IsLowSurrogate(s1, 0));
        Console.WriteLine("B4) s1[2]? - {0}", (System.Boolean)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}", (System.Boolean)Char.
            IsSurrogatePair(cHigh, cLow));
        Console.WriteLine("C2) s1[0] and s1[1]? - {0}", (System.Boolean)Char.
            IsSurrogatePair(s1, 0));
        Console.WriteLine("C3) s1[1] and s1[2]? - {0}", (System.Boolean)Char.
            IsSurrogatePair(s1, 1));
        Console.WriteLine("C4) s1[2] and s1[3]? - {0}", (System.Boolean)Char.
            IsSurrogatePair(s1, 2));
        Console.WriteLine(divider);
    } //main
} //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 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0
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