项目
11/18/2011

UnicodeEncoding.GetByteCount Method (String)

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Calculates the number of bytes produced by encoding the characters in the specified string.

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

Syntax

'Declaration
<SecuritySafeCriticalAttribute> _
Public Overrides Function GetByteCount ( _
    s As String _
) As Integer

[SecuritySafeCriticalAttribute]
public override int GetByteCount(
    string s
)

Parameters

s
Type: System.String
The string that contains the set of characters to encode.

Return Value

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

Exceptions

Exception	Condition
ArgumentNullException	s is null (Nothing).
ArgumentOutOfRangeException	The resulting number of bytes is greater than the maximum number that can be returned as an integer.
ArgumentException	Error detection is enabled, and s contains an invalid sequence of characters.
EncoderFallbackException	A fallback occurred (see Understanding Encodings for fuller explanation).

Remarks

To calculate the exact array size required by GetBytes 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.

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

Examples

The following code example demonstrates how to use the GetByteCount method to return the number of bytes required to encode a String using UnicodeEncoding.

Imports System.Text

Class Example

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim chars As String = "Unicode Encoding Example"

      Dim uni As New UnicodeEncoding()
      Dim byteCount As Integer = uni.GetByteCount(chars)
      outputBlock.Text += String.Format("{0} bytes needed to encode string.", byteCount) & vbCrLf
   End Sub 'Main
End Class 'UnicodeEncodingExample

using System;
using System.Text;

class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      String chars = "Unicode Encoding Example";

      UnicodeEncoding Unicode = new UnicodeEncoding();
      int byteCount = Unicode.GetByteCount(chars);
      outputBlock.Text += String.Format(
          "{0} bytes needed to encode string.", byteCount
      ) + "\n";
   }
}

Version Information

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

Platforms

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

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