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

Calculates the number of bytes that would be produced by encoding a set of characters from the specified character array.

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

[SecuritySafeCriticalAttribute]
public override int GetByteCount(
	char[] chars,
	int index,
	int count
)

Parameters

chars
Type: System.Char[]
The character array containing the set of characters to encode.
index
Type: System.Int32
The zero-based index of the first character to encode.
count
Type: System.Int32
The number of characters to encode.

Return Value

Type: System.Int32
The number of bytes produced by encoding the specified characters.

ExceptionCondition
ArgumentNullException

chars is null.

ArgumentOutOfRangeException

index or count is less than zero.

-or-

index and count do not denote a valid range in chars.

-or-

The resulting number of bytes is greater than the maximum number that can be returned as an integer.

ArgumentException

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

EncoderFallbackException

A fallback occurred (see Understanding Encodings for complete explanation).

To calculate the exact array size required by the GetBytes method to store the resulting bytes, call the GetByteCount method. To calculate the maximum array size, call the GetMaxByteCount method. The GetByteCount method generally allocates 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.

NoteNote:

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 Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      // Unicode characters.
      Char[] chars = new Char[] {
            '\u0023', // #
            '\u0025', // %
            '\u03a0', // Pi
            '\u03a3'  // Sigma
        };

      UTF8Encoding utf8 = new UTF8Encoding();
      int byteCount = utf8.GetByteCount(chars, 1, 2);
      outputBlock.Text += String.Format(
          "{0} bytes needed to encode characters.", byteCount
      ) + "\n";
   }
}


Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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