Char.ConvertFromUtf32(Int32) 方法

定义

命名空间:

System

程序集:

System.Runtime.dll

程序集:

netstandard.dll

程序集:

mscorlib.dll

将指定的 Unicode 码位转换为 UTF-16 编码字符串。

C#

public static string ConvertFromUtf32 (int utf32);

参数

utf32

Int32

21 位 Unicode 码位。

返回

String

由一个 Char 对象或一个 Char 对象的代理项对组成的字符串，等效于 utf32 参数所指定的码位。

例外

ArgumentOutOfRangeException

utf32 不是一个从 U+0 到 U+10FFFF 范围内的有效 21 位 Unicode 码位（从 U+D800 到 U+DFFF 范围的代理项对除外）。

示例

下面的代码示例演示了 ConvertToUtf32 和 ConvertFromUtf32 方法。

C#

// 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

*/

注解

使用此方法可以在使用和等方法测试字符串之前将21位 Unicode 码位转换为 UTF-16 编码字符串。 IsLowSurrogate(Char) IsHighSurrogate(Char)

(BMP) 的基本多语言平面之外的有效码位始终产生有效的代理项对。 但是，根据 Unicode 标准，BMP 内的有效码位可能不会生成有效的结果，因为在转换中未使用任何语言处理。 出于此原因，请使用 System.Text.UTF32Encoding 类将大容量 32 utf-16 数据转换为大容量 utf-16 数据。

适用于

另请参阅

• Rune
• ConvertToUtf32(Char, Char)
• UTF32Encoding