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UnicodeEncoding.GetBytes Method (String, Int32, Int32, Byte[], Int32)

Encodes a set of characters from the specified String into the specified byte array.

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

public override int GetBytes(
	string s,
	int charIndex,
	int charCount,
	byte[] bytes,
	int byteIndex


Type: System.String
The String containing the set of characters to encode.
Type: System.Int32
The index of the first character to encode.
Type: System.Int32
The number of characters to encode.
Type: System.Byte[]
The byte array to contain the resulting sequence of bytes.
Type: System.Int32
The index at which to start writing the resulting sequence of bytes.

Return Value

Type: System.Int32
The actual number of bytes written into bytes.


s is null (Nothing).


bytes is null (Nothing).


charIndex or charCount or byteIndex is less than zero.


charIndex and charCount do not denote a valid range in chars.


byteIndex is not a valid index in bytes.


Error detection is enabled, and s contains an invalid sequence of characters.


bytes does not have enough capacity from byteIndex to the end of the array to accommodate the resulting bytes.


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


EncoderFallback is set to EncoderExceptionFallback.

To calculate the exact array size required by GetBytes to store the resulting bytes, the application uses GetByteCount. To calculate the maximum array size, the application should use GetMaxByteCount. The GetByteCount method generally allows allocation of less memory, while the GetMaxByteCount method generally executes faster.

With error detection, an invalid sequence causes this method to throw a ArgumentException. Without error detection, invalid sequences are ignored, and no exception is thrown.

Data to be converted, such as data read from a stream, might be available only in sequential blocks. In this case, or if the amount of data is so large that it needs to be divided into smaller blocks, the application should use the Decoder or the Encoder provided by the GetDecoder method or the GetEncoder method, respectively.


To ensure that the encoded bytes are decoded properly, the application should prefix encoded bytes with a preamble.

The following code example demonstrates how to encode a range of elements from a Unicode character array and store the encoded bytes in a range of elements in a byte array.

using System;
using System.Text;

class UnicodeEncodingExample {
    public static void Main() {
        Byte[] bytes;
        // Unicode characters.
        Char[] chars = new Char[] {
            '\u0023', // #
            '\u0025', // %
            '\u03a0', // Pi
            '\u03a3'  // Sigma

        UnicodeEncoding Unicode = new UnicodeEncoding();

        int byteCount = Unicode.GetByteCount(chars, 1, 2);
        bytes = new Byte[byteCount];
        int bytesEncodedCount = Unicode.GetBytes(chars, 1, 2, bytes, 0);

            "{0} bytes used to encode characters.", bytesEncodedCount

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

.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.