Encoder Class

Converts a set of characters into a sequence of bytes.

System.Object
  System.Text.Encoder

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

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

The Encoder type exposes the following members.

  NameDescription
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibraryEncoderInitializes a new instance of the Encoder class.
Top

  NameDescription
Public propertyFallbackGets or sets a EncoderFallback object for the current Encoder object.
Public propertyFallbackBufferGets the EncoderFallbackBuffer object associated with the current Encoder object.
Top

  NameDescription
Public methodSupported by the XNA FrameworkConvert(Char*, Int32, Byte*, Int32, Boolean, Int32, Int32, Boolean)Converts a buffer of Unicode characters to an encoded byte sequence and stores the result in another buffer.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryConvert(Char[], Int32, Int32, Byte[], Int32, Int32, Boolean, Int32, Int32, Boolean)Converts an array of Unicode characters to an encoded byte sequence and stores the result in an array of bytes.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibraryFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by the XNA FrameworkGetByteCount(Char*, Int32, Boolean)When overridden in a derived class, calculates the number of bytes produced by encoding a set of characters starting at the specified character pointer. A parameter indicates whether to clear the internal state of the encoder after the calculation.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetByteCount(Char[], Int32, Int32, Boolean)When overridden in a derived class, calculates the number of bytes produced by encoding a set of characters from the specified character array. A parameter indicates whether to clear the internal state of the encoder after the calculation.
Public methodSupported by the XNA FrameworkGetBytes(Char*, Int32, Byte*, Int32, Boolean)When overridden in a derived class, encodes a set of characters starting at the specified character pointer and any characters in the internal buffer into a sequence of bytes that are stored starting at the specified byte pointer. A parameter indicates whether to clear the internal state of the encoder after the conversion.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetBytes(Char[], Int32, Int32, Byte[], Int32, Boolean)When overridden in a derived class, encodes a set of characters from the specified character array and any characters in the internal buffer into the specified byte array. A parameter indicates whether to clear the internal state of the encoder after the conversion.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibraryMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodResetWhen overridden in a derived class, sets the encoder back to its initial state.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryToStringReturns a string that represents the current object. (Inherited from Object.)
Top

To obtain an instance of an implementation of the Encoder class, the application should use the GetEncoder method of an Encoding implementation.

The GetByteCount method determines how many bytes result in encoding a set of Unicode characters, and the GetBytes method performs the actual encoding. There are several versions of both of these methods available in the Encoder class. For more information, see Encoding.GetBytes.

A Encoder object maintains state information between successive calls to GetBytes or Convert methods so that it can correctly encode character sequences that span blocks. The Encoder also preserves trailing characters at the end of data blocks and uses the trailing characters in the next encoding operation. For example, a data block might end with an unmatched high surrogate, and the matching low surrogate might be in the next data block. 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.

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 Encoder object.

Version Considerations

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 how to convert an array of Unicode characters into blocks of bytes using a specified encoding. For comparison, the array of characters is first encoded using UTF7Encoding. Next, the array of characters is encoded using an Encoder.


using System;
using System.Text;

class EncoderTest {
    public static void Main() {
        // The characters to encode.
        Char[] chars = new Char[] {
            '\u0023', // #
            '\u0025', // %
            '\u03a0', // Pi
            '\u03a3'  // Sigma
        };

        // Encode characters using an Encoding object.
        Encoding encoding = Encoding.UTF7;
        Console.WriteLine("Using Encoding\n--------------");

        // Encode complete array for comparison.
        Byte[] allCharactersFromEncoding = encoding.GetBytes(chars);
        Console.WriteLine("All characters encoded:");
        ShowArray(allCharactersFromEncoding);

        // Encode characters, one-by-one.
        // The Encoding object will NOT maintain state between calls.
        Byte[] firstchar = encoding.GetBytes(chars, 0, 1);
        Console.WriteLine("First character:");
        ShowArray(firstchar);

        Byte[] secondchar = encoding.GetBytes(chars, 1, 1);
        Console.WriteLine("Second character:");
        ShowArray(secondchar);

        Byte[] thirdchar = encoding.GetBytes(chars, 2, 1);
        Console.WriteLine("Third character:");
        ShowArray(thirdchar);

        Byte[] fourthchar = encoding.GetBytes(chars, 3, 1);
        Console.WriteLine("Fourth character:");
        ShowArray(fourthchar);


        // Now, encode characters using an Encoder object.
        Encoder encoder = encoding.GetEncoder();
        Console.WriteLine("Using Encoder\n-------------");

        // Encode complete array for comparison.
        Byte[] allCharactersFromEncoder = new Byte[encoder.GetByteCount(chars, 0, chars.Length, true)];
        encoder.GetBytes(chars, 0, chars.Length, allCharactersFromEncoder, 0, true);
        Console.WriteLine("All characters encoded:");
        ShowArray(allCharactersFromEncoder);

        // Do not flush state; i.e. maintain state between calls.
        bool bFlushState = false;

        // Encode characters one-by-one.
        // By maintaining state, the Encoder will not store extra bytes in the output.
        Byte[] firstcharNoFlush = new Byte[encoder.GetByteCount(chars, 0, 1, bFlushState)];
        encoder.GetBytes(chars, 0, 1, firstcharNoFlush, 0, bFlushState);
        Console.WriteLine("First character:");
        ShowArray(firstcharNoFlush);

        Byte[] secondcharNoFlush = new Byte[encoder.GetByteCount(chars, 1, 1, bFlushState)];
        encoder.GetBytes(chars, 1, 1, secondcharNoFlush, 0, bFlushState);
        Console.WriteLine("Second character:");
        ShowArray(secondcharNoFlush);

        Byte[] thirdcharNoFlush = new Byte[encoder.GetByteCount(chars, 2, 1, bFlushState)];
        encoder.GetBytes(chars, 2, 1, thirdcharNoFlush, 0, bFlushState);
        Console.WriteLine("Third character:");
        ShowArray(thirdcharNoFlush);

        // Must flush state on last call to GetBytes().
        bFlushState = true;

        Byte[] fourthcharNoFlush = new Byte[encoder.GetByteCount(chars, 3, 1, bFlushState)];
        encoder.GetBytes(chars, 3, 1, fourthcharNoFlush, 0, bFlushState);
        Console.WriteLine("Fourth character:");
        ShowArray(fourthcharNoFlush);
    }

    public static void ShowArray(Array theArray) {
        foreach (Object o in theArray) {
            Console.Write("[{0}]", o);
        }
        Console.WriteLine("\n");
    }
}

/* This code example produces the following output.

Using Encoding
--------------
All characters encoded:
[43][65][67][77][65][74][81][79][103][65][54][77][45]

First character:
[43][65][67][77][45]

Second character:
[43][65][67][85][45]

Third character:
[43][65][54][65][45]

Fourth character:
[43][65][54][77][45]

Using Encoder
-------------
All characters encoded:
[43][65][67][77][65][74][81][79][103][65][54][77][45]

First character:
[43][65][67]

Second character:
[77][65][74]

Third character:
[81][79][103]

Fourth character:
[65][54][77][45]


*/


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Was this page helpful?
(1500 characters remaining)
Thank you for your feedback

Community Additions

ADD
Show:
© 2014 Microsoft