Encoding.GetByteCount Method (Char[], Int32, Int32)
Assembly: mscorlib (in mscorlib.dll)
public abstract int GetByteCount ( char[] chars, int index, int count )
public abstract function GetByteCount ( chars : char[], index : int, count : int ) : int
Not applicable.
Parameters
- chars
The character array containing the set of characters to encode.
- index
The index of the first character to encode.
- count
The number of characters to encode.
Return Value
The number of bytes produced by encoding the specified characters.| Exception type | Condition |
|---|---|
| chars is a null reference (Nothing in Visual Basic). | |
| index or count is less than zero. -or- index and count do not denote a valid range in chars. | |
| A fallback occurred (see Understanding Encodings for complete explanation) -and- EncoderFallback is set to EncoderExceptionFallback. |
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 allows allocation of 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.
The following code example determines the number of bytes required to encode three characters from a character array, encodes the characters, and displays the resulting bytes.
using namespace System; using namespace System::Text; void PrintCountsAndBytes( array<Char>^chars, int index, int count, Encoding^ enc ); void PrintHexBytes( array<Byte>^bytes ); int main() { // 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) array<Char>^myChars = gcnew array<Char>{ L'z',L'a',L'\u0306',L'\u01FD',L'\u03B2',L'\xD8FF',L'\xDCFF' }; // Get different encodings. Encoding^ u7 = Encoding::UTF7; Encoding^ u8 = Encoding::UTF8; Encoding^ u16LE = Encoding::Unicode; Encoding^ u16BE = Encoding::BigEndianUnicode; Encoding^ u32 = Encoding::UTF32; // Encode three characters starting at index 4, and print out the counts and the resulting bytes. PrintCountsAndBytes( myChars, 4, 3, u7 ); PrintCountsAndBytes( myChars, 4, 3, u8 ); PrintCountsAndBytes( myChars, 4, 3, u16LE ); PrintCountsAndBytes( myChars, 4, 3, u16BE ); PrintCountsAndBytes( myChars, 4, 3, u32 ); } void PrintCountsAndBytes( array<Char>^chars, int index, int count, Encoding^ enc ) { // Display the name of the encoding used. Console::Write( "{0,-30} :", enc ); // Display the exact byte count. int iBC = enc->GetByteCount( chars, index, count ); Console::Write( " {0,-3}", iBC ); // Display the maximum byte count. int iMBC = enc->GetMaxByteCount( count ); Console::Write( " {0,-3} :", iMBC ); // Encode the array of chars. array<Byte>^bytes = enc->GetBytes( chars, index, count ); // The following is an alternative way to encode the array of chars: // byte[] bytes = new byte[iBC]; // enc.GetBytes( chars, index, count, bytes, bytes.GetLowerBound(0) ); // Display all the encoded bytes. PrintHexBytes( bytes ); } void PrintHexBytes( array<Byte>^bytes ) { if ( (bytes == nullptr) || (bytes->Length == 0) ) Console::WriteLine( "<none>" ); else { for ( int i = 0; i < bytes->Length; i++ ) Console::Write( "{0:X2} ", bytes[ i ] ); Console::WriteLine(); } } /* This code produces the following output. System.Text.UTF7Encoding : 10 11 :2B 41 37 4C 59 2F 39 7A 2F 2D 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 System.Text.UTF32Encoding : 8 16 :B2 03 00 00 FF FC 04 00 */
import System.*;
import System.Text.*;
public class SamplesEncoding
{
public static void main(String[] args)
{
// 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)
char myChars[] = new char[] { 'z', 'a', '\u0306', '\u01FD', '\u03B2',
'\uD8FF', '\uDCFF' };
// Get different encodings.
Encoding u7 = Encoding.get_UTF7();
Encoding u8 = Encoding.get_UTF8();
Encoding u16LE = Encoding.get_Unicode();
Encoding u16BE = Encoding.get_BigEndianUnicode();
Encoding u32 = Encoding.get_UTF32();
// Encode three characters starting at index 4,
// and print out the counts and the resulting bytes.
PrintCountsAndBytes(myChars, 4, 3, u7);
PrintCountsAndBytes(myChars, 4, 3, u8);
PrintCountsAndBytes(myChars, 4, 3, u16LE);
PrintCountsAndBytes(myChars, 4, 3, u16BE);
PrintCountsAndBytes(myChars, 4, 3, u32);
} //main
public static void PrintCountsAndBytes(char chars[], int index,
int count, Encoding enc)
{
// Display the name of the encoding used.
Console.Write("{0,-30} :", enc.ToString());
// Display the exact byte count.
int iBC = enc.GetByteCount(chars, index, count);
Console.Write(" {0,-3}", String.valueOf(iBC));
// Display the maximum byte count.
int iMBC = enc.GetMaxByteCount(count);
Console.Write(" {0,-3} :", String.valueOf(iMBC));
// Encode the array of chars.
ubyte bytes[] = enc.GetBytes(chars, index, count);
// The following is an alternative way to encode the array of chars:
// byte[] bytes = new byte[iBC];
// enc.GetBytes( chars, index, count, bytes, bytes.GetLowerBound(0) );
// Display all the encoded bytes.
PrintHexBytes(bytes);
} //PrintCountsAndBytes
public static void PrintHexBytes(ubyte bytes[])
{
if(bytes == null || bytes.length == 0) {
Console.WriteLine("<none>");
}
else {
for(int i = 0; i < bytes.length; i++) {
Console.Write("{0:X2} ",
((System.Byte)bytes[i]).ToString("X2"));
}
Console.WriteLine();
}
} //PrintHexBytes
} //SamplesEncoding
/*
This code produces the following output.
System.Text.UTF7Encoding : 10 11 :2B 41 37 4C 59 2F 39 7A 2F 2D
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
System.Text.UTF32Encoding : 8 16 :B2 03 00 00 FF FC 04 00
*/
Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.