Encoding.UTF32 属性
定义
重要
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使用小字节顺序获取 UTF-32 格式的编码。
public:
static property System::Text::Encoding ^ UTF32 { System::Text::Encoding ^ get(); };public static System.Text.Encoding UTF32 { get; }static member UTF32 : System.Text.EncodingPublic Shared ReadOnly Property UTF32 As Encoding属性值
使用小字节字节顺序的 UTF-32 格式的编码对象。
示例
下面的示例确定对字符数组进行编码、对字符进行编码以及显示生成的字节所需的字节数。
using System;
using System.Text;
public class SamplesEncoding {
public static void Main() {
// The characters to encode:
// Latin Small Letter Z (U+007A)
// Latin Small Letter A (U+0061)
// Combining Breve (U+0306)
// Latin Small Letter AE With Acute (U+01FD)
// Greek Small Letter Beta (U+03B2)
// a high-surrogate value (U+D8FF)
// a low-surrogate value (U+DCFF)
char[] myChars = new char[] { 'z', 'a', '\u0306', '\u01FD', '\u03B2', '\uD8FF', '\uDCFF' };
// Get different encodings.
Encoding u7 = Encoding.UTF7;
Encoding u8 = Encoding.UTF8;
Encoding u16LE = Encoding.Unicode;
Encoding u16BE = Encoding.BigEndianUnicode;
Encoding u32 = Encoding.UTF32;
// Encode the entire array, and print out the counts and the resulting bytes.
PrintCountsAndBytes( myChars, u7 );
PrintCountsAndBytes( myChars, u8 );
PrintCountsAndBytes( myChars, u16LE );
PrintCountsAndBytes( myChars, u16BE );
PrintCountsAndBytes( myChars, u32 );
}
public static void PrintCountsAndBytes( char[] chars, Encoding enc ) {
// Display the name of the encoding used.
Console.Write( "{0,-30} :", enc.ToString() );
// Display the exact byte count.
int iBC = enc.GetByteCount( chars );
Console.Write( " {0,-3}", iBC );
// Display the maximum byte count.
int iMBC = enc.GetMaxByteCount( chars.Length );
Console.Write( " {0,-3} :", iMBC );
// Encode the array of chars.
byte[] bytes = enc.GetBytes( chars );
// Display all the encoded bytes.
PrintHexBytes( bytes );
}
public static void PrintHexBytes( byte[] bytes ) {
if (( bytes == null ) || ( bytes.Length == 0 ))
{
Console.WriteLine( "<none>" );
}
else {
for ( int i = 0; i < bytes.Length; i++ )
Console.Write( "{0:X2} ", bytes[i] );
Console.WriteLine();
}
}
}
/*
This code produces the following output.
System.Text.UTF7Encoding : 18 23 :7A 61 2B 41 77 59 42 2F 51 4F 79 32 50 2F 63 2F 77 2D
System.Text.UTF8Encoding : 12 24 :7A 61 CC 86 C7 BD CE B2 F1 8F B3 BF
System.Text.UnicodeEncoding : 14 16 :7A 00 61 00 06 03 FD 01 B2 03 FF D8 FF DC
System.Text.UnicodeEncoding : 14 16 :00 7A 00 61 03 06 01 FD 03 B2 D8 FF DC FF
System.Text.UTF32Encoding : 24 32 :7A 00 00 00 61 00 00 00 06 03 00 00 FD 01 00 00 B2 03 00 00 FF FC 04 00
*/
Imports System.Text
Public Class SamplesEncoding
Public Shared Sub Main()
' The characters to encode:
' Latin Small Letter Z (U+007A)
' Latin Small Letter A (U+0061)
' Combining Breve (U+0306)
' Latin Small Letter AE With Acute (U+01FD)
' Greek Small Letter Beta (U+03B2)
' a high-surrogate value (U+D8FF)
' a low-surrogate value (U+DCFF)
Dim myChars() As Char = {"z"c, "a"c, ChrW(&H0306), ChrW(&H01FD), ChrW(&H03B2), ChrW(&HD8FF), ChrW(&HDCFF)}
' Get different encodings.
Dim u7 As Encoding = Encoding.UTF7
Dim u8 As Encoding = Encoding.UTF8
Dim u16LE As Encoding = Encoding.Unicode
Dim u16BE As Encoding = Encoding.BigEndianUnicode
Dim u32 As Encoding = Encoding.UTF32
' Encode the entire array, and print out the counts and the resulting bytes.
PrintCountsAndBytes(myChars, u7)
PrintCountsAndBytes(myChars, u8)
PrintCountsAndBytes(myChars, u16LE)
PrintCountsAndBytes(myChars, u16BE)
PrintCountsAndBytes(myChars, u32)
End Sub
Public Shared Sub PrintCountsAndBytes(chars() As Char, enc As Encoding)
' Display the name of the encoding used.
Console.Write("{0,-30} :", enc.ToString())
' Display the exact byte count.
Dim iBC As Integer = enc.GetByteCount(chars)
Console.Write(" {0,-3}", iBC)
' Display the maximum byte count.
Dim iMBC As Integer = enc.GetMaxByteCount(chars.Length)
Console.Write(" {0,-3} :", iMBC)
' Encode the array of chars.
Dim bytes As Byte() = enc.GetBytes(chars)
' Display all the encoded bytes.
PrintHexBytes(bytes)
End Sub
Public Shared Sub PrintHexBytes(bytes() As Byte)
If bytes Is Nothing OrElse bytes.Length = 0 Then
Console.WriteLine("<none>")
Else
Dim i As Integer
For i = 0 To bytes.Length - 1
Console.Write("{0:X2} ", bytes(i))
Next i
Console.WriteLine()
End If
End Sub
End Class
'This code produces the following output.
'
'System.Text.UTF7Encoding : 18 23 :7A 61 2B 41 77 59 42 2F 51 4F 79 32 50 2F 63 2F 77 2D
'System.Text.UTF8Encoding : 12 24 :7A 61 CC 86 C7 BD CE B2 F1 8F B3 BF
'System.Text.UnicodeEncoding : 14 16 :7A 00 61 00 06 03 FD 01 B2 03 FF D8 FF DC
'System.Text.UnicodeEncoding : 14 16 :00 7A 00 61 03 06 01 FD 03 B2 D8 FF DC FF
'System.Text.UTF32Encoding : 24 32 :7A 00 00 00 61 00 00 00 06 03 00 00 FD 01 00 00 B2 03 00 00 FF FC 04 00
注解
UTF32Encoding此属性返回的对象可能没有适合你的应用的行为。 它使用替换回退来替换无法编码的每个字符串，以及无法使用 Unicode REPLACEMENT CHARACTER（U+FFFE）解码的每个字节。 相反，可以调用UTF32Encoding.UTF32Encoding(Boolean, Boolean, Boolean)构造函数来实例化UTF32Encoding其回退为一个或一个EncoderFallbackExceptionDecoderFallbackException的对象，如以下示例所示。
using System;
using System.Text;
public class Example
{
public static void Main()
{
Encoding enc = new UTF32Encoding(false, true, true);
string value = "\u00C4 \uD802\u0033 \u00AE";
try {
byte[] bytes= enc.GetBytes(value);
foreach (var byt in bytes)
Console.Write("{0:X2} ", byt);
Console.WriteLine();
string value2 = enc.GetString(bytes);
Console.WriteLine(value2);
}
catch (EncoderFallbackException e) {
Console.WriteLine("Unable to encode {0} at index {1}",
e.IsUnknownSurrogate() ?
String.Format("U+{0:X4} U+{1:X4}",
Convert.ToUInt16(e.CharUnknownHigh),
Convert.ToUInt16(e.CharUnknownLow)) :
String.Format("U+{0:X4}",
Convert.ToUInt16(e.CharUnknown)),
e.Index);
}
}
}
// The example displays the following output:
// Unable to encode U+D802 at index 2
Imports System.Text
Module Example
Public Sub Main()
Dim enc As Encoding = New UTF32Encoding(False, True, True)
Dim value As String = String.Format("{0} {1}{2} {3}",
ChrW(&h00C4), ChrW(&hD802), ChrW(&h0033), ChrW(&h00AE))
Try
Dim bytes() As Byte = enc.GetBytes(value)
For Each byt As Byte In bytes
Console.Write("{0:X2} ", byt)
Next
Console.WriteLine()
Dim value2 As String = enc.GetString(bytes)
Console.WriteLine(value2)
Catch e As EncoderFallbackException
Console.WriteLine("Unable to encode {0} at index {1}",
If(e.IsUnknownSurrogate(),
String.Format("U+{0:X4} U+{1:X4}",
Convert.ToUInt16(e.CharUnknownHigh),
Convert.ToUInt16(e.CharUnknownLow)),
String.Format("U+{0:X4}",
Convert.ToUInt16(e.CharUnknown))),
e.Index)
End Try
End Sub
End Module
' The example displays the following output:
' Unable to encode U+D802 at index 2
有关小字节顺序的讨论，请参阅 Encoding。
有关.NET支持的编码以及要使用的 Unicode 编码的讨论，请参阅 .NET0>Character Encoding。
