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Decoder.GetChars Method (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.

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

public abstract int GetChars(
	byte[] bytes,
	int byteIndex,
	int byteCount,
	char[] chars,
	int charIndex
)

Parameters

bytes
Type: System.Byte[]

The byte array containing the sequence of bytes to decode.

byteIndex
Type: System.Int32

The index of the first byte to decode.

byteCount
Type: System.Int32

The number of bytes to decode.

chars
Type: System.Char[]

The character array to contain the resulting set of characters.

charIndex
Type: System.Int32

The index at which to start writing the resulting set of characters.

Return Value

Type: System.Int32
The actual number of characters written into chars.

ExceptionCondition
ArgumentNullException

bytes is null (Nothing).

-or-

chars is null (Nothing).

ArgumentOutOfRangeException

byteIndex or byteCount or charIndex is less than zero.

-or-

byteindex and byteCount do not denote a valid range in bytes.

-or-

charIndex is not a valid index in chars.

ArgumentException

chars does not have enough capacity from charIndex to the end of the array to accommodate the resulting characters.

DecoderFallbackException

A fallback occurred (see Character Encoding in the .NET Framework for fuller explanation)

-and-

Fallback is set to DecoderExceptionFallback.

Remember that the Decoder object saves state between calls to GetChars. When the application is done with a stream of data, it should set the flush parameter to true to make sure that the state information is flushed. With this setting, the decoder ignores invalid bytes at the end of the data block and clears the internal buffer.

To calculate the exact array size that GetChars requires to store the resulting characters, the application should use GetCharCount.

If GetChars is called with flush set to false, the decoder stores trailing bytes at the end of the data block in an internal buffer and uses them in the next decoding operation. The application should call GetCharCount on a block of data immediately before calling GetChars on the same block, so that any trailing bytes from the previous block are included in the calculation.

If your application is to convert many segments of an input stream, consider using the Convert method. GetChars will throw an exception if the output buffer isn't large enough, but Convert will fill as much space as possible and return the bytes read and chars written. Also see the Encoding.GetChars topic for more comments.

The following example demonstrates how to decode a range of elements from a byte array and store them in a Unicode character array. The GetCharCount method is used to calculate the number of characters needed to store the decoded elements in the array bytes. The GetChars method decodes the specified elements in the byte array and stores them in the new character array.

using System;
using System.Text;

class UnicodeEncodingExample {
    public static void Main() {
        Char[] chars;
        Byte[] bytes = new Byte[] {
            85, 0, 110, 0, 105, 0, 99, 0, 111, 0, 100, 0, 101, 0
        };

        Decoder uniDecoder = Encoding.Unicode.GetDecoder();

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

        Console.WriteLine(
            "{0} characters used to decode bytes.", charsDecodedCount
        );

        Console.Write("Decoded chars: ");
        foreach (Char c in chars) {
            Console.Write("[{0}]", c);
        }
        Console.WriteLine();
    }
}

/* This code example produces the following output.

7 characters used to decode bytes.
Decoded chars: [U][n][i][c][o][d][e]

*/

.NET Framework

Supported in: 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 Silverlight 8.1, Windows Phone Silverlight 8

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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