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UTF8Encoding.GetEncoder Method

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

Namespace:  System.Text
Assembly:  mscorlib (in mscorlib.dll)
public override Encoder GetEncoder()

Return Value

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

The Encoder.GetBytes method converts sequential blocks of characters into sequential blocks of bytes, in a manner similar to the GetBytes method. However, a Encoder maintains state information between calls so 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.

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

The following example demonstrates how to use the GetEncoder method to obtain an encoder to convert a sequence of characters into a UTF-8 encoded sequence of bytes.

using System;
using System.Text;

class UTF8EncodingExample {
    public static void Main() {
        Char[] chars = new Char[] {'a', 'b', 'c', '\u0300', '\ua0a0'};
        Byte[] bytes;

        Encoder utf8Encoder = Encoding.UTF8.GetEncoder();

        int byteCount = utf8Encoder.GetByteCount(chars, 2, 3, true);
        bytes = new Byte[byteCount];
        int bytesEncodedCount = utf8Encoder.GetBytes(chars, 2, 3, bytes, 0, true);

        Console.WriteLine(
            "{0} bytes used to encode characters.", bytesEncodedCount
        );

        Console.Write("Encoded bytes: ");
        foreach (Byte b in bytes) {
            Console.Write("[{0}]", b);
        }
        Console.WriteLine();
    }
}

.NET Framework

Supported in: 4.5.1, 4.5, 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

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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