Encoding.GetMaxCharCount-Methode
Berechnet beim Überschreiben in einer abgeleiteten Klasse die maximale Anzahl an Zeichen, die beim Decodieren der angegebenen Anzahl von Bytes erzeugt wird.
Namespace: System.Text
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public MustOverride Function GetMaxCharCount ( _
byteCount As Integer _
) As Integer
'Usage
Dim instance As Encoding
Dim byteCount As Integer
Dim returnValue As Integer
returnValue = instance.GetMaxCharCount(byteCount)
public abstract int GetMaxCharCount (
int byteCount
)
public:
virtual int GetMaxCharCount (
int byteCount
) abstract
public abstract int GetMaxCharCount (
int byteCount
)
public abstract function GetMaxCharCount (
byteCount : int
) : int
Parameter
- byteCount
Die Anzahl der zu decodierenden Bytes.
Rückgabewert
Die maximale Anzahl der Zeichen, die beim Decodieren der angegebenen Anzahl von Bytes erzeugt wird.
Ausnahmen
| Ausnahmetyp | Bedingung |
|---|---|
byteCount ist kleiner als 0 (null). |
Hinweise
Verwenden Sie die GetCharCount-Methode zum Berechnen der exakten Arraygröße, die von GetChars zum Speichern der sich ergebenden Zeichen benötigt wird. Verwenden Sie die GetMaxCharCount-Methode zum Berechnen der maximalen Arraygröße. Die GetCharCount-Methode ermöglicht Ihnen, weniger Speicher zuzuordnen, wohingegen die GetMaxCharCount-Methode in der Regel schneller ausgeführt wird.
Hinweise für Implementierer Bei sämtlichen Implementierungen von Encoding muss sichergestellt werden, dass keine Ausnahmen durch Pufferüberlauf ausgelöst werden, wenn die Puffergröße den Berechnungsergebnissen dieser Methode entspricht.
Beispiel
Im folgenden Codebeispiel wird eine Zeichenfolge in ein Bytearray codiert, und anschließend werden die Bytes in ein Zeichenarray decodiert.
Imports System
Imports System.Text
Imports Microsoft.VisualBasic
Public Class SamplesEncoding
Public Shared Sub Main()
' Create two instances of UTF32Encoding: one with little-endian byte order and one with big-endian byte order.
Dim u32LE As Encoding = Encoding.GetEncoding("utf-32")
Dim u32BE As Encoding = Encoding.GetEncoding("utf-32BE")
' Use a string containing the following characters:
' 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)
Dim myStr As String = "za" & ChrW(&H0306) & ChrW(&H01FD) & ChrW(&H03B2)
' Encode the string using the big-endian byte order.
' 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 barrBE(u32BE.GetByteCount(myStr) - 1) As Byte
u32BE.GetBytes(myStr, 0, myStr.Length, barrBE, 0)
' Encode the string using the little-endian byte order.
' 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 barrLE(u32LE.GetByteCount(myStr) - 1) As Byte
u32LE.GetBytes(myStr, 0, myStr.Length, barrLE, 0)
' Get the char counts, and decode the byte arrays.
Console.Write("BE array with BE encoding : ")
PrintCountsAndChars(barrBE, u32BE)
Console.Write("LE array with LE encoding : ")
PrintCountsAndChars(barrLE, u32LE)
End Sub 'Main
Public Shared Sub PrintCountsAndChars(bytes() As Byte, enc As Encoding)
' Display the name of the encoding used.
Console.Write("{0,-25} :", enc.ToString())
' Display the exact character count.
Dim iCC As Integer = enc.GetCharCount(bytes)
Console.Write(" {0,-3}", iCC)
' Display the maximum character count.
Dim iMCC As Integer = enc.GetMaxCharCount(bytes.Length)
Console.Write(" {0,-3} :", iMCC)
' Decode the bytes and display the characters.
Dim chars As Char() = enc.GetChars(bytes)
Console.WriteLine(chars)
End Sub 'PrintCountsAndChars
End Class 'SamplesEncoding
'This code produces the following output. The question marks take the place of characters that cannot be displayed at the console.
'
'BE array with BE encoding : System.Text.UTF32Encoding : 5 12 :za??
'LE array with LE encoding : System.Text.UTF32Encoding : 5 12 :za??
using System;
using System.Text;
public class SamplesEncoding {
public static void Main() {
// Create two instances of UTF32Encoding: one with little-endian byte order and one with big-endian byte order.
Encoding u32LE = Encoding.GetEncoding( "utf-32" );
Encoding u32BE = Encoding.GetEncoding( "utf-32BE" );
// Use a string containing the following characters:
// 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)
String myStr = "za\u0306\u01FD\u03B2";
// Encode the string using the big-endian byte order.
byte[] barrBE = new byte[u32BE.GetByteCount( myStr )];
u32BE.GetBytes( myStr, 0, myStr.Length, barrBE, 0 );
// Encode the string using the little-endian byte order.
byte[] barrLE = new byte[u32LE.GetByteCount( myStr )];
u32LE.GetBytes( myStr, 0, myStr.Length, barrLE, 0 );
// Get the char counts, and decode the byte arrays.
Console.Write( "BE array with BE encoding : " );
PrintCountsAndChars( barrBE, u32BE );
Console.Write( "LE array with LE encoding : " );
PrintCountsAndChars( barrLE, u32LE );
}
public static void PrintCountsAndChars( byte[] bytes, Encoding enc ) {
// Display the name of the encoding used.
Console.Write( "{0,-25} :", enc.ToString() );
// Display the exact character count.
int iCC = enc.GetCharCount( bytes );
Console.Write( " {0,-3}", iCC );
// Display the maximum character count.
int iMCC = enc.GetMaxCharCount( bytes.Length );
Console.Write( " {0,-3} :", iMCC );
// Decode the bytes and display the characters.
char[] chars = enc.GetChars( bytes );
Console.WriteLine( chars );
}
}
/*
This code produces the following output. The question marks take the place of characters that cannot be displayed at the console.
BE array with BE encoding : System.Text.UTF32Encoding : 5 12 :za??
LE array with LE encoding : System.Text.UTF32Encoding : 5 12 :za??
*/
using namespace System;
using namespace System::Text;
void PrintCountsAndChars( array<Byte>^bytes, Encoding^ enc );
int main()
{
// Create two instances of UTF32Encoding: one with little-endian byte order and one with big-endian byte order.
Encoding^ u32LE = Encoding::GetEncoding( "utf-32" );
Encoding^ u32BE = Encoding::GetEncoding( "utf-32BE" );
// Use a string containing the following characters:
// 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)
String^ myStr = "za\u0306\u01FD\u03B2";
// Encode the string using the big-endian byte order.
array<Byte>^barrBE = gcnew array<Byte>(u32BE->GetByteCount( myStr ));
u32BE->GetBytes( myStr, 0, myStr->Length, barrBE, 0 );
// Encode the string using the little-endian byte order.
array<Byte>^barrLE = gcnew array<Byte>(u32LE->GetByteCount( myStr ));
u32LE->GetBytes( myStr, 0, myStr->Length, barrLE, 0 );
// Get the char counts, and decode the byte arrays.
Console::Write( "BE array with BE encoding : " );
PrintCountsAndChars( barrBE, u32BE );
Console::Write( "LE array with LE encoding : " );
PrintCountsAndChars( barrLE, u32LE );
}
void PrintCountsAndChars( array<Byte>^bytes, Encoding^ enc )
{
// Display the name of the encoding used.
Console::Write( "{0,-25} :", enc );
// Display the exact character count.
int iCC = enc->GetCharCount( bytes );
Console::Write( " {0,-3}", iCC );
// Display the maximum character count.
int iMCC = enc->GetMaxCharCount( bytes->Length );
Console::Write( " {0,-3} :", iMCC );
// Decode the bytes and display the characters.
array<Char>^chars = enc->GetChars( bytes );
Console::WriteLine( chars );
}
/*
This code produces the following output. The question marks take the place of characters that cannot be displayed at the console.
BE array with BE encoding : System.Text.UTF32Encoding : 5 12 :za??
LE array with LE encoding : System.Text.UTF32Encoding : 5 12 :za??
*/
import System.*;
import System.Text.*;
public class SamplesEncoding
{
public static void main(String[] args)
{
// Create two instances of UTF32Encoding: one with little-endian
// byte order and one with big-endian byte order.
Encoding u32LE = Encoding.GetEncoding("utf-32");
Encoding u32BE = Encoding.GetEncoding("utf-32BE");
// Use a string containing the following characters:
// 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)
String myStr = "za\u0306\u01FD\u03B2";
// Encode the string using the big-endian byte order.
ubyte barrBE[] = new ubyte[u32BE.GetByteCount(myStr)];
u32BE.GetBytes(myStr, 0, myStr.get_Length(), barrBE, 0);
// Encode the string using the little-endian byte order.
ubyte barrLE[] = new ubyte[u32LE.GetByteCount(myStr)];
u32LE.GetBytes(myStr, 0, myStr.get_Length(), barrLE, 0);
// Get the char counts, and decode the byte arrays.
Console.Write("BE array with BE encoding : ");
PrintCountsAndChars(barrBE, u32BE);
Console.Write("LE array with LE encoding : ");
PrintCountsAndChars(barrLE, u32LE);
} //main
public static void PrintCountsAndChars(ubyte bytes[], Encoding enc)
{
// Display the name of the encoding used.
Console.Write("{0,-25} :", enc.ToString());
// Display the exact character count.
int iCC = enc.GetCharCount(bytes);
Console.Write(" {0,-3}", String.valueOf(iCC));
// Display the maximum character count.
int iMCC = enc.GetMaxCharCount(bytes.length);
Console.Write(" {0,-3} :", String.valueOf(iMCC));
// Decode the bytes and display the characters.
char chars[] = enc.GetChars(bytes);
Console.WriteLine(chars);
} //PrintCountsAndChars
} //SamplesEncoding
/*
This code produces the following output. The question marks take the place
of characters that cannot be displayed at the console.
BE array with BE encoding : System.Text.UTF32Encoding : 5 12 :za??
LE array with LE encoding : System.Text.UTF32Encoding : 5 12 :za??
*/
Plattformen
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile für Pocket PC, Windows Mobile für Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.
Versionsinformationen
.NET Framework
Unterstützt in: 2.0, 1.1, 1.0
.NET Compact Framework
Unterstützt in: 2.0, 1.0
Siehe auch
Referenz
Encoding-Klasse
Encoding-Member
System.Text-Namespace
GetChars
GetString
GetCharCount
GetDecoder