Encoding.GetByteCount Method (String)

When overridden in a derived class, calculates the number of bytes produced by encoding the characters in the specified string.

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

Syntax

'Declaration
Public Overridable Function GetByteCount ( _
    s As String _
) As Integer
public virtual 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 nulla null reference (Nothing in Visual Basic).

EncoderFallbackException

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

Remarks

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

For a discussion of programming considerations for use of this method, see the Encoding class description.

Examples

The following code example determines the number of bytes required to encode a string or a range in the string, encodes the characters, and displays the resulting bytes.

Imports System.Text

Public Class Example
   Private Shared outputBlock As System.Windows.Controls.TextBlock

   Public Shared Sub Demo(ByVal outBlock As System.Windows.Controls.TextBlock)
      outputBlock = outBlock
      ' The characters to encode:
      '    Latin Small Letter Z (U+007A)
      '    Latin Small Letter A (U+0061)
      '    Combining Breve (U+0306)
      '    Latin Small Letter AE With Acute (U+01FD)
      '    Greek Small Letter Beta (U+03B2)
      '    a high-surrogate value (U+D8FF)
      '    a low-surrogate value (U+DCFF)
      Dim myStr As String = "za" & ChrW(&H306) & ChrW(&H1FD) & ChrW(&H3B2) & ChrW(&HD8FF) & ChrW(&HDCFF)

      ' Get different encodings.
      Dim u8 As Encoding = Encoding.UTF8
      Dim u16LE As Encoding = Encoding.Unicode
      Dim u16BE As Encoding = Encoding.BigEndianUnicode

      ' Encode the entire string, and print out the counts and the resulting bytes.
      outputBlock.Text &= "Encoding the entire string:" & vbCrLf
      PrintCountsAndBytes(myStr, u8)
      PrintCountsAndBytes(myStr, u16LE)
      PrintCountsAndBytes(myStr, u16BE)

      outputBlock.Text &= vbCrLf

      ' Encode three characters starting at index 4, and print out the counts and the resulting bytes.
      outputBlock.Text &= "Encoding the characters from index 4 through 6:" & vbCrLf
      PrintCountsAndBytes(myStr, 4, 3, u8)
      PrintCountsAndBytes(myStr, 4, 3, u16LE)
      PrintCountsAndBytes(myStr, 4, 3, u16BE)
   End Sub 

   Public Overloads Shared Sub PrintCountsAndBytes(ByVal s As String, ByVal enc As Encoding)
      ' Display the name of the encoding used.
      outputBlock.Text += String.Format("{0,-30} :", enc.ToString())

      ' Display the exact byte count.
      Dim iBC As Integer = enc.GetByteCount(s)
      outputBlock.Text += String.Format(" {0,-3}", iBC)

      ' Display the maximum byte count.
      Dim iMBC As Integer = enc.GetMaxByteCount(s.Length)
      outputBlock.Text += String.Format(" {0,-3} :", iMBC)

      ' Encode the entire string.
      Dim bytes As Byte() = enc.GetBytes(s)

      ' Display all the encoded bytes.
      PrintHexBytes(bytes)
   End Sub 'PrintCountsAndBytes

   Public Overloads Shared Sub PrintCountsAndBytes(ByVal s As String, ByVal index As Integer, ByVal count As Integer, ByVal enc As Encoding)
      ' Display the name of the encoding used.
      outputBlock.Text += String.Format("{0,-30} :", enc.ToString())

      ' Display the exact byte count.
      Dim iBC As Integer = enc.GetByteCount(s.ToCharArray(), index, count)
      outputBlock.Text += String.Format(" {0,-3}", iBC)

      ' Display the maximum byte count.
      Dim iMBC As Integer = enc.GetMaxByteCount(count)
      outputBlock.Text += String.Format(" {0,-3} :", iMBC)

      ' Encode a range of characters in the string.
      ' NOTE: In VB.NET, arrays contain one extra element by default.
      '       The following line creates the array with the exact number of elements required.
      Dim bytes(iBC - 1) As Byte
      enc.GetBytes(s, index, count, bytes, bytes.GetLowerBound(0))

      ' Display all the encoded bytes.
      PrintHexBytes(bytes)
   End Sub 

   Public Shared Sub PrintHexBytes(ByVal bytes() As Byte)
      If bytes Is Nothing OrElse bytes.Length = 0 Then
         outputBlock.Text &= "<none>" & vbCrLf
      Else
         Dim i As Integer
         For i = 0 To bytes.Length - 1
            outputBlock.Text += String.Format("{0:X2} ", bytes(i))
         Next i
         outputBlock.Text &= vbCrLf
      End If
   End Sub
End Class
' This example produces the following output.
'    Encoding the entire string:
'    System.Text.UTF8Encoding       : 12  24  :7A 61 CC 86 C7 BD CE B2 F1 8F B3 BF
'    System.Text.UnicodeEncoding    : 14  16  :7A 00 61 00 06 03 FD 01 B2 03 FF D8 FF DC
'    System.Text.UnicodeEncoding    : 14  16  :00 7A 00 61 03 06 01 FD 03 B2 D8 FF DC FF
'    
'    Encoding the characters from index 4 through 6:
'    System.Text.UTF8Encoding       : 6   12  :CE B2 F1 8F B3 BF
'    System.Text.UnicodeEncoding    : 6   8   :B2 03 FF D8 FF DC
'    System.Text.UnicodeEncoding    : 6   8   :03 B2 D8 FF DC FF
using System;
using System.Text;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      // The characters to encode:
      //    Latin Small Letter Z (U+007A)
      //    Latin Small Letter A (U+0061)
      //    Combining Breve (U+0306)
      //    Latin Small Letter AE With Acute (U+01FD)
      //    Greek Small Letter Beta (U+03B2)
      //    a high-surrogate value (U+D8FF)
      //    a low-surrogate value (U+DCFF)
      String myStr = "za\u0306\u01FD\u03B2\uD8FF\uDCFF";

      // Get different encodings.
      Encoding u8 = Encoding.UTF8;
      Encoding u16LE = Encoding.Unicode;
      Encoding u16BE = Encoding.BigEndianUnicode;

      // Encode the entire string, and print out the counts and the resulting bytes.
      outputBlock.Text += "Encoding the entire string:\n";
      PrintCountsAndBytes(outputBlock, myStr, u8);
      PrintCountsAndBytes(outputBlock, myStr, u16LE);
      PrintCountsAndBytes(outputBlock, myStr, u16BE);

      outputBlock.Text += "\n";

      // Encode three characters starting at index 4, and print out the counts and the resulting bytes.
      outputBlock.Text += "Encoding the characters from index 4 through 6:\n";
      PrintCountsAndBytes(outputBlock, myStr, 4, 3, u8);
      PrintCountsAndBytes(outputBlock, myStr, 4, 3, u16LE);
      PrintCountsAndBytes(outputBlock, myStr, 4, 3, u16BE);
   }

   public static void PrintCountsAndBytes(System.Windows.Controls.TextBlock outputBlock, 
                                          String s, Encoding enc)
   {
      // Display the name of the encoding used.
      outputBlock.Text += String.Format("{0,-30} :", enc.ToString());

      // Display the exact byte count.
      int iBC = enc.GetByteCount(s);
      outputBlock.Text += String.Format(" {0,-3}", iBC);

      // Display the maximum byte count.
      int iMBC = enc.GetMaxByteCount(s.Length);
      outputBlock.Text += String.Format(" {0,-3} :", iMBC);

      // Encode the entire string.
      byte[] bytes = enc.GetBytes(s);

      // Display all the encoded bytes.
      PrintHexBytes(outputBlock, bytes);
   }

   public static void PrintCountsAndBytes(System.Windows.Controls.TextBlock outputBlock, 
                                          String s, int index, int count, Encoding enc)
   {
      // Display the name of the encoding used.
      outputBlock.Text += String.Format("{0,-30} :", enc.ToString());

      // Display the exact byte count.
      int iBC = enc.GetByteCount(s.ToCharArray(), index, count);
      outputBlock.Text += String.Format(" {0,-3}", iBC);

      // Display the maximum byte count.
      int iMBC = enc.GetMaxByteCount(count);
      outputBlock.Text += String.Format(" {0,-3} :", iMBC);

      // Encode a range of characters in the string.
      byte[] bytes = new byte[iBC];
      enc.GetBytes(s, index, count, bytes, bytes.GetLowerBound(0));

      // Display all the encoded bytes.
      PrintHexBytes(outputBlock, bytes);
   }

   public static void PrintHexBytes(System.Windows.Controls.TextBlock outputBlock, 
                                    byte[] bytes)
   {
      if ((bytes == null) || (bytes.Length == 0))
         outputBlock.Text += "<none>" + "\n";
      else
      {
         for (int i = 0; i < bytes.Length; i++)
            outputBlock.Text += String.Format("{0:X2} ", bytes[i]);
         outputBlock.Text += "\n";
      }
   }
}
/* 
This example produces the following output.

Encoding the entire string:
System.Text.UTF8Encoding       : 12  24  :7A 61 CC 86 C7 BD CE B2 F1 8F B3 BF
System.Text.UnicodeEncoding    : 14  16  :7A 00 61 00 06 03 FD 01 B2 03 FF D8 FF DC
System.Text.UnicodeEncoding    : 14  16  :00 7A 00 61 03 06 01 FD 03 B2 D8 FF DC FF

Encoding the characters from index 4 through 6:
System.Text.UTF8Encoding       : 6   12  :CE B2 F1 8F B3 BF
System.Text.UnicodeEncoding    : 6   8   :B2 03 FF D8 FF DC
System.Text.UnicodeEncoding    : 6   8   :03 B2 D8 FF DC FF
*/

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.