Decoder Class

 

Converts a sequence of encoded bytes into a set of characters.

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

System.Object
  System.Text.Decoder

[SerializableAttribute]
[ComVisibleAttribute(true)]
public abstract class Decoder

NameDescription
System_CAPS_protmethodDecoder()

Initializes a new instance of the Decoder class.

NameDescription
System_CAPS_pubpropertyFallback

Gets or sets a DecoderFallback object for the current Decoder object.

System_CAPS_pubpropertyFallbackBuffer

Gets the DecoderFallbackBuffer object associated with the current Decoder object.

NameDescription
System_CAPS_pubmethodConvert(Byte*, Int32, Char*, Int32, Boolean, Int32, Int32, Boolean)

Converts a buffer of encoded bytes to UTF-16 encoded characters and stores the result in another buffer.

System_CAPS_pubmethodConvert(Byte[], Int32, Int32, Char[], Int32, Int32, Boolean, Int32, Int32, Boolean)

Converts an array of encoded bytes to UTF-16 encoded characters and stores the result in a character array.

System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethodFinalize()

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethodGetCharCount(Byte*, Int32, Boolean)

When overridden in a derived class, calculates the number of characters produced by decoding a sequence of bytes starting at the specified byte pointer. A parameter indicates whether to clear the internal state of the decoder after the calculation.

System_CAPS_pubmethodGetCharCount(Byte[], Int32, Int32)

When overridden in a derived class, calculates the number of characters produced by decoding a sequence of bytes from the specified byte array.

System_CAPS_pubmethodGetCharCount(Byte[], Int32, Int32, Boolean)

When overridden in a derived class, calculates the number of characters produced by decoding a sequence of bytes from the specified byte array. A parameter indicates whether to clear the internal state of the decoder after the calculation.

System_CAPS_pubmethodGetChars(Byte*, Int32, Char*, Int32, Boolean)

When overridden in a derived class, decodes a sequence of bytes starting at the specified byte pointer and any bytes in the internal buffer into a set of characters that are stored starting at the specified character pointer. A parameter indicates whether to clear the internal state of the decoder after the conversion.

System_CAPS_pubmethodGetChars(Byte[], Int32, Int32, Char[], Int32)

When overridden in a derived class, decodes a sequence of bytes from the specified byte array and any bytes in the internal buffer into the specified character array.

System_CAPS_pubmethodGetChars(Byte[], Int32, Int32, Char[], Int32, Boolean)

When overridden in a derived class, decodes a sequence of bytes from the specified byte array and any bytes in the internal buffer into the specified character array. A parameter indicates whether to clear the internal state of the decoder after the conversion.

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_protmethodMemberwiseClone()

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_pubmethodReset()

When overridden in a derived class, sets the decoder back to its initial state.

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

To obtain an instance of an implementation of the Decoder class, the application should use the GetDecoder method of an Encoding implementation.

The GetCharCount method determines how many characters result in decoding a sequence of bytes, and the GetChars method performs the actual decoding. There are several versions of both of these methods available in the Decoder class. For more information, see Encoding.GetChars. A Decoder object maintains state information between successive calls to GetChars or Convert methods 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.

System_CAPS_noteNote

When the application is done with a stream of data, it should make sure that the state information is flushed by setting the flush parameter to true in the appropriate method call. If an exception occurs or if the application switches streams, it should call Reset to clear the internal state of the Decoder object.

A Decoder or Encoder object can be serialized during a conversion operation. The state of the object is retained if it is deserialized in the same version of the .NET Framework, but lost if it is deserialized in another version.

Notes to Inheritors:

When your application inherits from this class, it must override all the members.

The following example demonstrates the use of a Decoder to convert two different byte arrays into a character array. One of the character's bytes spans the arrays. This is similar to what a StreamReader object does internally when reading a stream.

using System;
using System.Text;
public class dec
{
    public static void Main()
    {
        // These bytes in UTF-8 correspond to 3 different Unicode
        // characters: space (U+0020), # (U+0023), and the biohazard
        // symbol (U+2623).  Note the biohazard symbol requires 3 bytes
        // in UTF-8 (hexadecimal e2, 98, a3).  Decoders store state across
        // multiple calls to GetChars, handling the case when one char
        // is in multiple byte arrays.
        byte[] bytes1 = { 0x20, 0x23, 0xe2 };
        byte[] bytes2 = { 0x98, 0xa3 };
        char[] chars = new char[3];

        Decoder d = Encoding.UTF8.GetDecoder();
        int charLen = d.GetChars(bytes1, 0, bytes1.Length, chars, 0);
        // The value of charLen should be 2 now.
        charLen += d.GetChars(bytes2, 0, bytes2.Length, chars, charLen);
        foreach(char c in chars)
            Console.Write("U+{0:X4}  ", (ushort)c);
    }
}

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1

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

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