UTF8Encoding.GetByteCount Method (Char[], Int32, Int32)

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.

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

The following example demonstrates how to use the GetByteCount method to return the number of bytes required to encode an array of Unicode characters, using UTF8Encoding.

using System;
using System.Text;

class UTF8EncodingExample {
    public static void Main() {
        // Unicode characters.
        Char[] chars = new Char[] {
            '\u0023', // #
            '\u0025', // %
            '\u03a0', // Pi
            '\u03a3'  // Sigma
        };

        UTF8Encoding utf8 = new UTF8Encoding();
        int byteCount = utf8.GetByteCount(chars, 1, 2);
        Console.WriteLine(
            "{0} bytes needed to encode characters.", byteCount
        );
    }
}

.NET Framework

.NET Framework Client Profile

Portable Class Library

.NET for Windows Store apps

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.

Reference