UTF8Encoding.GetDecoder Method

Obtains a decoder that converts a UTF-8 encoded sequence of bytes into a sequence of Unicode characters.

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

public override Decoder GetDecoder()

Return Value

Type: System.Text.Decoder
A Decoder that converts a UTF-8 encoded sequence of bytes into a sequence of Unicode characters.

The Decoder.GetChars method converts sequential blocks of bytes into sequential blocks of characters, in a manner similar to the UTF8Encoding.GetChars method. However, a Decoder object 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 operations in which a single set of data spans multiple blocks.

If error detection is enabled, that is, the throwOnInvalidCharacters parameter of the constructor is 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.

The following example demonstrates how to use the GetDecoder method to obtain a UTF-8 decoder. The decoder converts a sequence of bytes into a sequence of characters.

using System;
using System.Text;

class Example
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
      Char[] chars;
      Byte[] bytes = new Byte[] {
            99, 204, 128, 234, 130, 160

      Decoder utf8Decoder = Encoding.UTF8.GetDecoder();

      int charCount = utf8Decoder.GetCharCount(bytes, 0, bytes.Length);
      chars = new Char[charCount];
      int charsDecodedCount = utf8Decoder.GetChars(bytes, 0, bytes.Length, chars, 0);

      outputBlock.Text += String.Format(
          "{0} characters used to decode bytes.", charsDecodedCount
      ) + "\n";

      outputBlock.Text += "Decoded chars: ";
      foreach (Char c in chars)
         outputBlock.Text += String.Format("[{0}]", c);
      outputBlock.Text += "\n";


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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