UTF32Encoding.GetDecoder Method

Definition

Obtains a decoder that converts a UTF-32 encoded sequence of bytes into a sequence of Unicode characters.

public:
 override System::Text::Decoder ^ GetDecoder();
public override System.Text.Decoder GetDecoder ();
override this.GetDecoder : unit -> System.Text.Decoder
Public Overrides Function GetDecoder () As Decoder

Returns

Decoder

A Decoder that converts a UTF-32 encoded sequence of bytes into a sequence of Unicode characters.

Examples

The following example uses an encoder and a decoder to encode a string into an array of bytes, and then decode the bytes into an array of characters.

using namespace System;
using namespace System::Text;
int main()
{
   
   // Get an encoder and a decoder from UTF32Encoding.
   UTF32Encoding ^ u32 = gcnew UTF32Encoding( false,true,true );
   Encoder^ myEnc = u32->GetEncoder();
   Decoder^ myDec = u32->GetDecoder();
   
   // 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)
   array<Char>^myChars = gcnew array<Char>(5){
      L'z',L'a',L'\u0306',L'\u01FD',L'\u03B2'
   };
   Console::Write( "The original characters : " );
   Console::WriteLine( myChars );
   
   // Encode the character array.
   int iBC = myEnc->GetByteCount( myChars, 0, myChars.Length, true );
   array<Byte>^myBytes = gcnew array<Byte>(iBC);
   myEnc->GetBytes( myChars, 0, myChars.Length, myBytes, 0, true );
   
   // Print the resulting bytes.
   Console::Write( "Using the encoder       : " );
   for ( int i = 0; i < myBytes.Length; i++ )
      Console::Write( "{0:X2} ", myBytes[ i ] );
   Console::WriteLine();
   
   // Decode the byte array back into an array of characters.
   int iCC = myDec->GetCharCount( myBytes, 0, myBytes.Length, true );
   array<Char>^myDecodedChars = gcnew array<Char>(iCC);
   myDec->GetChars( myBytes, 0, myBytes.Length, myDecodedChars, 0, true );
   
   // Print the resulting characters.
   Console::Write( "Using the decoder       : " );
   Console::WriteLine( myDecodedChars );
}

/* 
This code produces the following output.  The question marks take the place of characters that cannot be displayed at the console.

The original characters : za??
Using the encoder       : 7A 00 00 00 61 00 00 00 06 03 00 00 FD 01 00 00 B2 03 00 00
Using the decoder       : za??

*/
using System;
using System.Text;

public class SamplesUTF32Encoding  {

   public static void Main()  {

      // Get an encoder and a decoder from UTF32Encoding.
      UTF32Encoding u32 = new UTF32Encoding( false, true, true );
      Encoder myEnc = u32.GetEncoder();
      Decoder myDec = u32.GetDecoder();

      // 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)
      char[] myChars = new char[5] { 'z', 'a', '\u0306', '\u01FD', '\u03B2' };
      Console.Write( "The original characters : " );
      Console.WriteLine( myChars );

      // Encode the character array.
      int iBC  = myEnc.GetByteCount( myChars, 0, myChars.Length, true );
      byte[] myBytes = new byte[iBC];
      myEnc.GetBytes( myChars, 0, myChars.Length, myBytes, 0, true );

      // Print the resulting bytes.
      Console.Write( "Using the encoder       : " );
      for ( int i = 0; i < myBytes.Length; i++ )
         Console.Write( "{0:X2} ", myBytes[i] );
      Console.WriteLine();

      // Decode the byte array back into an array of characters.
      int iCC  = myDec.GetCharCount( myBytes, 0, myBytes.Length, true );
      char[] myDecodedChars = new char[iCC];
      myDec.GetChars( myBytes, 0, myBytes.Length, myDecodedChars, 0, true );

      // Print the resulting characters.
      Console.Write( "Using the decoder       : " );
      Console.WriteLine( myDecodedChars );
   }
}


/* 
This code produces the following output.  The question marks take the place of characters that cannot be displayed at the console.

The original characters : za??ß
Using the encoder       : 7A 00 00 00 61 00 00 00 06 03 00 00 FD 01 00 00 B2 03 00 00
Using the decoder       : za??ß

*/

Imports System.Text

Public Class SamplesUTF32Encoding   

   Public Shared Sub Main()

      ' Get an encoder and a decoder from UTF32Encoding.
      Dim u32 As New UTF32Encoding(False, True, True)
      Dim myEnc As Encoder = u32.GetEncoder()
      Dim myDec As Decoder = u32.GetDecoder()

      ' 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)
      Dim myChars() As Char = {"z"c, "a"c, ChrW(&H0306), ChrW(&H01FD), ChrW(&H03B2)}
      Console.Write("The original characters : ")
      Console.WriteLine(myChars)

      ' Encode the character array.
      Dim iBC As Integer = myEnc.GetByteCount(myChars, 0, myChars.Length, True)
      ' NOTE: In Visual Basic, arrays contain one extra element by default.
      '       The following line creates an array with the exact number of elements required.
      Dim myBytes(iBC - 1) As Byte
      myEnc.GetBytes(myChars, 0, myChars.Length, myBytes, 0, True)

      ' Print the resulting bytes.
      Console.Write("Using the encoder       : ")
      Dim i As Integer
      For i = 0 To myBytes.Length - 1
         Console.Write("{0:X2} ", myBytes(i))
      Next i
      Console.WriteLine()

      ' Decode the byte array back into an array of characters.
      Dim iCC As Integer = myDec.GetCharCount(myBytes, 0, myBytes.Length, True)
      ' NOTE: In Visual Basic, arrays contain one extra element by default.
      '       The following line creates an array with the exact number of elements required.
      Dim myDecodedChars(iCC - 1) As Char
      myDec.GetChars(myBytes, 0, myBytes.Length, myDecodedChars, 0, True)

      ' Print the resulting characters.
      Console.Write("Using the decoder       : ")
      Console.WriteLine(myDecodedChars)

   End Sub

End Class


'This code produces the following output.  The question marks take the place of characters that cannot be displayed at the console.
'
'The original characters : za??ß
'Using the encoder       : 7A 00 00 00 61 00 00 00 06 03 00 00 FD 01 00 00 B2 03 00 00
'Using the decoder       : za??ß

Remarks

The Decoder.GetChars method converts sequential blocks of bytes into sequential blocks of characters, in a manner similar to the GetChars method. However, a Decoder maintains state information between calls so it can correctly decode byte sequences that span blocks. The Decoder also preserves trailing bytes at the end of data blocks and uses the trailing bytes in the next decoding operation. Therefore, GetDecoder and GetEncoder are useful for network transmission and file operations, because those operations often deal with blocks of data instead of a complete data stream.

If error detection is enabled, that is, the throwOnInvalidCharacters parameter of the constructor was set to true, error detection is also enabled in the Decoder returned by this method. If error detection is enabled and an invalid sequence is encountered, the state of the decoder is undefined and processing must stop.

Applies to

See also