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Encoding Class

Represents a character encoding.

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

[SerializableAttribute] 
[ComVisibleAttribute(true)] 
public abstract class Encoding : ICloneable
/** @attribute SerializableAttribute() */ 
/** @attribute ComVisibleAttribute(true) */ 
public abstract class Encoding implements ICloneable
SerializableAttribute 
ComVisibleAttribute(true) 
public abstract class Encoding implements ICloneable

Encoding is the process of transforming a set of Unicode characters into a sequence of bytes. Decoding is the reverse; it is the process of transforming a sequence of encoded bytes into a set of Unicode characters.

The Unicode Standard assigns a code point (a number) to each character in every supported script. A Unicode Transformation Format (UTF) is a way to encode that code point. The Unicode Standard version 3.2 uses the following UTFs:

  • UTF-8, which represents each code point as a sequence of one to four bytes.

  • UTF-16, which represents each code point as a sequence of one to two 16-bit integers.

  • UTF-32, which represents each code point as a 32-bit integer.

The .NET Framework provides the following implementations of the Encoding class to support current Unicode encodings and other encodings:

  • ASCIIEncoding encodes Unicode characters as single 7-bit ASCII characters. This encoding only supports character values between U+0000 and U+007F. Code page 20127. Also available through the ASCII property.

  • UTF7Encoding encodes Unicode characters using the UTF-7 encoding. This encoding supports all Unicode character values. Code page 65000. Also available through the UTF7 property.

  • UTF8Encoding encodes Unicode characters using the UTF-8 encoding. This encoding supports all Unicode character values. Code page 65001. Also available through the UTF8 property.

  • UnicodeEncoding encodes Unicode characters using the UTF-16 encoding. Both little-endian (code page 1200) and big-endian (code page 1201) byte orders are supported. Also available through the Unicode property and the BigEndianUnicode property.

  • UTF32Encoding encodes Unicode characters using the UTF-32 encoding. Both little-endian (code page 65005) and big-endian (code page 65006) byte orders are supported. Also available through the UTF32 property.

Use the GetEncoding method to obtain other encodings. Use the GetEncodings method to get a list of all encodings.

The following table lists the encodings and their associated code pages. An asterisk in the last column indicates that the code page is natively supported by the .NET Framework, regardless of the underlying platform.

Code Page

Name

Display Name

37

IBM037

IBM EBCDIC (US-Canada)

437

IBM437

OEM United States

500

IBM500

IBM EBCDIC (International)

708

ASMO-708

Arabic (ASMO 708)

720

DOS-720

Arabic (DOS)

737

ibm737

Greek (DOS)

775

ibm775

Baltic (DOS)

850

ibm850

Western European (DOS)

852

ibm852

Central European (DOS)

855

IBM855

OEM Cyrillic

857

ibm857

Turkish (DOS)

858

IBM00858

OEM Multilingual Latin I

860

IBM860

Portuguese (DOS)

861

ibm861

Icelandic (DOS)

862

DOS-862

Hebrew (DOS)

863

IBM863

French Canadian (DOS)

864

IBM864

Arabic (864)

865

IBM865

Nordic (DOS)

866

cp866

Cyrillic (DOS)

869

ibm869

Greek, Modern (DOS)

870

IBM870

IBM EBCDIC (Multilingual Latin-2)

874

windows-874

Thai (Windows)

875

cp875

IBM EBCDIC (Greek Modern)

932

shift_jis

Japanese (Shift-JIS)

936

gb2312

Chinese Simplified (GB2312)

*

949

ks_c_5601-1987

Korean

950

big5

Chinese Traditional (Big5)

1026

IBM1026

IBM EBCDIC (Turkish Latin-5)

1047

IBM01047

IBM Latin-1

1140

IBM01140

IBM EBCDIC (US-Canada-Euro)

1141

IBM01141

IBM EBCDIC (Germany-Euro)

1142

IBM01142

IBM EBCDIC (Denmark-Norway-Euro)

1143

IBM01143

IBM EBCDIC (Finland-Sweden-Euro)

1144

IBM01144

IBM EBCDIC (Italy-Euro)

1145

IBM01145

IBM EBCDIC (Spain-Euro)

1146

IBM01146

IBM EBCDIC (UK-Euro)

1147

IBM01147

IBM EBCDIC (France-Euro)

1148

IBM01148

IBM EBCDIC (International-Euro)

1149

IBM01149

IBM EBCDIC (Icelandic-Euro)

1200

utf-16

Unicode

*

1201

unicodeFFFE

Unicode (Big-Endian)

*

1250

windows-1250

Central European (Windows)

1251

windows-1251

Cyrillic (Windows)

1252

Windows-1252

Western European (Windows)

*

1253

windows-1253

Greek (Windows)

1254

windows-1254

Turkish (Windows)

1255

windows-1255

Hebrew (Windows)

1256

windows-1256

Arabic (Windows)

1257

windows-1257

Baltic (Windows)

1258

windows-1258

Vietnamese (Windows)

1361

Johab

Korean (Johab)

10000

macintosh

Western European (Mac)

10001

x-mac-japanese

Japanese (Mac)

10002

x-mac-chinesetrad

Chinese Traditional (Mac)

10003

x-mac-korean

Korean (Mac)

*

10004

x-mac-arabic

Arabic (Mac)

10005

x-mac-hebrew

Hebrew (Mac)

10006

x-mac-greek

Greek (Mac)

10007

x-mac-cyrillic

Cyrillic (Mac)

10008

x-mac-chinesesimp

Chinese Simplified (Mac)

*

10010

x-mac-romanian

Romanian (Mac)

10017

x-mac-ukrainian

Ukrainian (Mac)

10021

x-mac-thai

Thai (Mac)

10029

x-mac-ce

Central European (Mac)

10079

x-mac-icelandic

Icelandic (Mac)

10081

x-mac-turkish

Turkish (Mac)

10082

x-mac-croatian

Croatian (Mac)

20000

x-Chinese-CNS

Chinese Traditional (CNS)

20001

x-cp20001

TCA Taiwan

20002

x-Chinese-Eten

Chinese Traditional (Eten)

20003

x-cp20003

IBM5550 Taiwan

20004

x-cp20004

TeleText Taiwan

20005

x-cp20005

Wang Taiwan

20105

x-IA5

Western European (IA5)

20106

x-IA5-German

German (IA5)

20107

x-IA5-Swedish

Swedish (IA5)

20108

x-IA5-Norwegian

Norwegian (IA5)

20127

us-ascii

US-ASCII

*

20261

x-cp20261

T.61

20269

x-cp20269

ISO-6937

20273

IBM273

IBM EBCDIC (Germany)

20277

IBM277

IBM EBCDIC (Denmark-Norway)

20278

IBM278

IBM EBCDIC (Finland-Sweden)

20280

IBM280

IBM EBCDIC (Italy)

20284

IBM284

IBM EBCDIC (Spain)

20285

IBM285

IBM EBCDIC (UK)

20290

IBM290

IBM EBCDIC (Japanese katakana)

20297

IBM297

IBM EBCDIC (France)

20420

IBM420

IBM EBCDIC (Arabic)

20423

IBM423

IBM EBCDIC (Greek)

20424

IBM424

IBM EBCDIC (Hebrew)

20833

x-EBCDIC-KoreanExtended

IBM EBCDIC (Korean Extended)

20838

IBM-Thai

IBM EBCDIC (Thai)

20866

koi8-r

Cyrillic (KOI8-R)

20871

IBM871

IBM EBCDIC (Icelandic)

20880

IBM880

IBM EBCDIC (Cyrillic Russian)

20905

IBM905

IBM EBCDIC (Turkish)

20924

IBM00924

IBM Latin-1

20932

EUC-JP

Japanese (JIS 0208-1990 and 0212-1990)

20936

x-cp20936

Chinese Simplified (GB2312-80)

*

20949

x-cp20949

Korean Wansung

*

21025

cp1025

IBM EBCDIC (Cyrillic Serbian-Bulgarian)

21866

koi8-u

Cyrillic (KOI8-U)

28591

iso-8859-1

Western European (ISO)

*

28592

iso-8859-2

Central European (ISO)

28593

iso-8859-3

Latin 3 (ISO)

28594

iso-8859-4

Baltic (ISO)

28595

iso-8859-5

Cyrillic (ISO)

28596

iso-8859-6

Arabic (ISO)

28597

iso-8859-7

Greek (ISO)

28598

iso-8859-8

Hebrew (ISO-Visual)

*

28599

iso-8859-9

Turkish (ISO)

28603

iso-8859-13

Estonian (ISO)

28605

iso-8859-15

Latin 9 (ISO)

29001

x-Europa

Europa

38598

iso-8859-8-i

Hebrew (ISO-Logical)

*

50220

iso-2022-jp

Japanese (JIS)

*

50221

csISO2022JP

Japanese (JIS-Allow 1 byte Kana)

*

50222

iso-2022-jp

Japanese (JIS-Allow 1 byte Kana - SO/SI)

*

50225

iso-2022-kr

Korean (ISO)

*

50227

x-cp50227

Chinese Simplified (ISO-2022)

*

51932

euc-jp

Japanese (EUC)

*

51936

EUC-CN

Chinese Simplified (EUC)

*

51949

euc-kr

Korean (EUC)

*

52936

hz-gb-2312

Chinese Simplified (HZ)

*

54936

GB18030

Chinese Simplified (GB18030)

*

57002

x-iscii-de

ISCII Devanagari

*

57003

x-iscii-be

ISCII Bengali

*

57004

x-iscii-ta

ISCII Tamil

*

57005

x-iscii-te

ISCII Telugu

*

57006

x-iscii-as

ISCII Assamese

*

57007

x-iscii-or

ISCII Oriya

*

57008

x-iscii-ka

ISCII Kannada

*

57009

x-iscii-ma

ISCII Malayalam

*

57010

x-iscii-gu

ISCII Gujarati

*

57011

x-iscii-pa

ISCII Punjabi

*

65000

utf-7

Unicode (UTF-7)

*

65001

utf-8

Unicode (UTF-8)

*

65005

utf-32

Unicode (UTF-32)

*

65006

utf-32BE

Unicode (UTF-32 Big-Endian)

*

The GetByteCount method determines how many bytes result in encoding a set of Unicode characters, and the GetBytes method performs the actual encoding.

Likewise, the GetCharCount method determines how many characters result in decoding a sequence of bytes, and the GetChars method performs the actual decoding.

If the data to be converted is available only in sequential blocks (such as data read from a stream) or if the amount of data is so large that it needs to be divided into smaller blocks, use the Decoder or the Encoder provided by the GetDecoder method or the GetEncoder method, respectively, of a derived class.

The UTF-16 and the UTF-32 encoders can use the big-endian byte order (most significant byte first) or the little-endian byte order (least significant byte first). For example, the Latin Capital Letter A (U+0041) is serialized as follows (in hexadecimal):

  • UTF-16 big-endian byte order: 00 41

  • UTF-16 little-endian byte order: 41 00

  • UTF-32 big-endian byte order: 00 00 00 41

  • UTF-32 little-endian byte order: 41 00 00 00

Optionally, the Encoding provides a preamble which is an array of bytes that can be prefixed to the sequence of bytes resulting from the encoding process. If the preamble contains a byte order mark (In Unicode, code point U+FEFF), it helps the decoder determine the byte order and the transformation format or UTF. The Unicode byte order mark is serialized as follows (in hexadecimal):

  • UTF-8: EF BB BF

  • UTF-16 big-endian byte order: FE FF

  • UTF-16 little-endian byte order: FF FE

  • UTF-32 big-endian byte order: 00 00 FE FF

  • UTF-32 little-endian byte order: FF FE 00 00

It is generally more efficient to store Unicode characters using the native byte order. For example, it is better to use the little-endian byte order on little-endian platforms, such as Intel machines.

The GetPreamble method returns an array of bytes that can include the byte order mark. If this byte array is prefixed to an encoded stream, it helps the decoder to identify the encoding format used.

For more information on byte order and the byte order mark, see The Unicode Standard at www.unicode.org.

The following code example converts a string from one encoding to another.

using System;
using System.Text;

namespace ConvertExample
{
   class ConvertExampleClass
   {
      static void Main()
      {
         string unicodeString = "This string contains the unicode character Pi(\u03a0)";

         // Create two different encodings.
         Encoding ascii = Encoding.ASCII;
         Encoding unicode = Encoding.Unicode;

         // Convert the string into a byte[].
         byte[] unicodeBytes = unicode.GetBytes(unicodeString);

         // Perform the conversion from one encoding to the other.
         byte[] asciiBytes = Encoding.Convert(unicode, ascii, unicodeBytes);
            
         // Convert the new byte[] into a char[] and then into a string.
         // This is a slightly different approach to converting to illustrate
         // the use of GetCharCount/GetChars.
         char[] asciiChars = new char[ascii.GetCharCount(asciiBytes, 0, asciiBytes.Length)];
         ascii.GetChars(asciiBytes, 0, asciiBytes.Length, asciiChars, 0);
         string asciiString = new string(asciiChars);

         // Display the strings created before and after the conversion.
         Console.WriteLine("Original string: {0}", unicodeString);
         Console.WriteLine("Ascii converted string: {0}", asciiString);
      }
   }
}

package ConvertExample; 

import System.*;
import System.Text.*;

class ConvertExampleClass
{
    public static void main(String[] args)
    {
        String unicodeString = 
                "This string contains the unicode character Pi(\u03a0)";

        // Create two different encodings.
        Encoding ascii = Encoding.get_ASCII();
        Encoding unicode = Encoding.get_Unicode();

        // Convert the string into a byte[].
        ubyte unicodeBytes[] = unicode.GetBytes(unicodeString);

        // Perform the conversion from one encoding to the other.
        ubyte asciiBytes[] = Encoding.Convert(unicode, ascii, unicodeBytes);

        // Convert the new byte[] into a char[] and then into a string.
        // This is a slightly different approach to converting to illustrate
        // the use of GetCharCount/GetChars.
        char asciiChars[] = new 
                char[ascii.GetCharCount(asciiBytes, 0, asciiBytes.length)];
        ascii.GetChars(asciiBytes, 0, asciiBytes.length, asciiChars, 0);
        String asciiString = new String(asciiChars);

        // Display the strings created before and after the conversion.
        Console.WriteLine("Original string: {0}", unicodeString);
        Console.WriteLine("Ascii converted string: {0}", asciiString);
    } //main
} //ConvertExampleClass 

System.Object
  System.Text.Encoding
     Derived Classes

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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