Char.ConvertToUtf32 Method (String, Int32)

Converts the value of a UTF-16 encoded character or surrogate pair at a specified position in a string into a Unicode code point.

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

public static int ConvertToUtf32(
	string s,
	int index
)

Parameters

s
Type: System.String

A string that contains a character or surrogate pair.

index
Type: System.Int32

The index position of the character or surrogate pair in s.

Return Value

Type: System.Int32
The 21-bit Unicode code point represented by the character or surrogate pair at the position in the s parameter specified by the index parameter.

ExceptionCondition
ArgumentNullException

s is null.

ArgumentOutOfRangeException

index is not a position within s.

ArgumentException

The specified index position contains a surrogate pair, and either the first character in the pair is not a valid high surrogate or the second character in the pair is not a valid low surrogate.

Use this method to convert a character or surrogate pair into a 21-bit Unicode code point. To convert UTF-16 data into UTF-32 data, use the System.Text.UTF32Encoding class.

The following code example demonstrates the ConvertToUtf32 and ConvertFromUtf32 methods.

// This example demonstrates the Char.ConvertFromUtf32() method 
//                           and Char.ConvertToUtf32() overloads. 
using System;

class Sample 
{
    public static void Main() 
    {
    int letterA = 0x0041;  //U+00041 = LATIN CAPITAL LETTER A 
    int music   = 0x1D161; //U+1D161 = MUSICAL SYMBOL SIXTEENTH NOTE 
    string s1;
    string comment   = "Create a UTF-16 encoded string from a code point.";
    string comment1b = "Create a code point from a UTF-16 encoded string.";
    string comment2b = "Create a code point from a surrogate pair at a certain position in a string.";
    string comment2c = "Create a code point from a high surrogate and a low surrogate code point.";

//  Convert code point U+0041 to UTF-16. The UTF-16 equivalent of  
//  U+0041 is a Char with hexadecimal value 0041.

    Console.WriteLine(comment);
    s1 = Char.ConvertFromUtf32(letterA);
    Console.Write("    1a) 0x{0:X} => ", letterA);
    Show(s1);
    Console.WriteLine();

//  Convert the lone UTF-16 character to a code point.

    Console.WriteLine(comment1b);
    letterA = Char.ConvertToUtf32(s1, 0);
    Console.Write("    1b) ");
    Show(s1);
    Console.WriteLine(" => 0x{0:X}", letterA);
    Console.WriteLine();

// ------------------------------------------------------------------- 

//  Convert the code point U+1D161 to UTF-16. The UTF-16 equivalent of  
//  U+1D161 is a surrogate pair with hexadecimal values D834 and DD61.

    Console.WriteLine(comment);
    s1 = Char.ConvertFromUtf32(music);
    Console.Write("    2a) 0x{0:X} => ", music);
    Show(s1);
    Console.WriteLine();

//  Convert the surrogate pair in the string at index position  
//  zero to a code point.

    Console.WriteLine(comment2b);
    music = Char.ConvertToUtf32(s1, 0);
    Console.Write("    2b) ");
    Show(s1);
    Console.WriteLine(" => 0x{0:X}", music);

//  Convert the high and low characters in the surrogate pair into a code point.

    Console.WriteLine(comment2c);
    music = Char.ConvertToUtf32(s1[0], s1[1]);
    Console.Write("    2c) ");
    Show(s1);
    Console.WriteLine(" => 0x{0:X}", music);
    }

    private static void Show(string s)
    {
    for (int x = 0; x < s.Length; x++)
        {
        Console.Write("0x{0:X}{1}", 
                       (int)s[x], 
                       ((x == s.Length-1)? String.Empty : ", "));
        }
    }
}
/*
This example produces the following results:

Create a UTF-16 encoded string from a code point.
    1a) 0x41 => 0x41
Create a code point from a UTF-16 encoded string.
    1b) 0x41 => 0x41

Create a UTF-16 encoded string from a code point.
    2a) 0x1D161 => 0xD834, 0xDD61
Create a code point from a surrogate pair at a certain position in a string.
    2b) 0xD834, 0xDD61 => 0x1D161
Create a code point from a high surrogate and a low surrogate code point.
    2c) 0xD834, 0xDD61 => 0x1D161

*/

.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

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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