Encoding.GetCharCount Encoding.GetCharCount Encoding.GetCharCount Encoding.GetCharCount Method

Definición

Cuando se reemplaza en una clase derivada, calcula el número de caracteres que se generan al descodificar una secuencia de bytes.When overridden in a derived class, calculates the number of characters produced by decoding a sequence of bytes.

Sobrecargas

GetCharCount(Byte[]) GetCharCount(Byte[]) GetCharCount(Byte[]) GetCharCount(Byte[])

Cuando se reemplaza en una clase derivada, calcula el número de caracteres que se generan al descodificar todos los bytes de la matriz de bytes especificada.When overridden in a derived class, calculates the number of characters produced by decoding all the bytes in the specified byte array.

GetCharCount(ReadOnlySpan<Byte>) GetCharCount(ReadOnlySpan<Byte>) GetCharCount(ReadOnlySpan<Byte>) GetCharCount(ReadOnlySpan<Byte>)
GetCharCount(Byte*, Int32) GetCharCount(Byte*, Int32) GetCharCount(Byte*, Int32)

Cuando se reemplaza en una clase derivada, calcula el número de caracteres que se generan al descodificar una secuencia de bytes a partir del puntero de bytes especificado.When overridden in a derived class, calculates the number of characters produced by decoding a sequence of bytes starting at the specified byte pointer.

GetCharCount(Byte[], Int32, Int32) GetCharCount(Byte[], Int32, Int32) GetCharCount(Byte[], Int32, Int32) GetCharCount(Byte[], Int32, Int32)

Cuando se reemplaza en una clase derivada, calcula el número de caracteres que se generan al descodificar una secuencia de bytes de la matriz de bytes especificada.When overridden in a derived class, calculates the number of characters produced by decoding a sequence of bytes from the specified byte array.

GetCharCount(Byte[]) GetCharCount(Byte[]) GetCharCount(Byte[]) GetCharCount(Byte[])

Cuando se reemplaza en una clase derivada, calcula el número de caracteres que se generan al descodificar todos los bytes de la matriz de bytes especificada.When overridden in a derived class, calculates the number of characters produced by decoding all the bytes in the specified byte array.

public:
 virtual int GetCharCount(cli::array <System::Byte> ^ bytes);
public virtual int GetCharCount (byte[] bytes);
abstract member GetCharCount : byte[] -> int
override this.GetCharCount : byte[] -> int
Public Overridable Function GetCharCount (bytes As Byte()) As Integer

Parámetros

bytes
Byte[]

Matriz de bytes que contiene la secuencia de bytes que se va a descodificar.The byte array containing the sequence of bytes to decode.

Devoluciones

Número de caracteres que se generan al descodificar la secuencia especificada de bytes.The number of characters produced by decoding the specified sequence of bytes.

Excepciones

Se ha producido una acción de reserva (vea Codificación de caracteres de .NET para obtener una explicación completa)A fallback occurred (see Character Encoding in .NET for complete explanation) - y --and- El valor de DecoderFallback está establecido en DecoderExceptionFallback.DecoderFallback is set to DecoderExceptionFallback.

Ejemplos

El ejemplo siguiente codifica una cadena en una matriz de bytes y, a continuación, descodifica los bytes en una matriz de caracteres.The following example encodes a string into an array of bytes, and then decodes the bytes into an array of characters.

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??�

*/
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??�

*/

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??�

Comentarios

Para calcular el tamaño exacto de matriz requerido GetChars(Byte[]) para almacenar los caracteres resultantes, debe usar el GetCharCount(Byte[]) método.To calculate the exact array size required by GetChars(Byte[]) to store the resulting characters, you should use the GetCharCount(Byte[]) method. Para calcular el tamaño máximo de la matriz, se debe utilizar el GetMaxCharCount(Int32) método.To calculate the maximum array size, you should use the GetMaxCharCount(Int32) method. El GetCharCount(Byte[]) método generalmente permite asignar menos memoria, mientras que el GetMaxCharCount método generalmente se ejecuta con mayor rapidez.The GetCharCount(Byte[]) method generally allows allocation of less memory, while the GetMaxCharCount method generally executes faster.

El GetCharCount(Byte[]) método determina el número de caracteres resultante de descodificar una secuencia de bytes y el GetChars(Byte[]) método realiza la descodificación real.The GetCharCount(Byte[]) method determines how many characters result in decoding a sequence of bytes, and the GetChars(Byte[]) method performs the actual decoding. El Encoding.GetChars método espera conversiones discretas, en contraposición al Decoder.GetChars método, que administra varios pasos en un único flujo de entrada.The Encoding.GetChars method expects discrete conversions, in contrast to the Decoder.GetChars method, which handles multiple passes on a single input stream.

Varias versiones de GetCharCount y GetChars son compatibles.Several versions of GetCharCount and GetChars are supported. Éstas son algunas consideraciones de programación para su uso de estos métodos:The following are some programming considerations for use of these methods:

  • La aplicación deba descodificar varios bytes de entrada de una página de códigos y procesar los bytes mediante varias llamadas.Your app might need to decode multiple input bytes from a code page and process the bytes using multiple calls. En este caso, probablemente necesite mantener el estado entre llamadas.In this case, you probably need to maintain state between calls.

  • Si la aplicación administra los resultados de la cadena, debe usar el GetString método.If your app handles string outputs, you should use the GetString method. Dado que este método debe comprobar la longitud de cadena y asignar un búfer, es algo más lento, pero resultante String tipo es preferible.Since this method must check string length and allocate a buffer, it is slightly slower, but the resulting String type is to be preferred.

  • La versión de bytes de GetChars(Byte*, Int32, Char*, Int32) permite algunas técnicas rápidas, especialmente con varias llamadas a los búferes grandes.The byte version of GetChars(Byte*, Int32, Char*, Int32) allows some fast techniques, particularly with multiple calls to large buffers. Tenga en cuenta, sin embargo, esta versión del método a veces es segura, puesto que los punteros son necesarios.Bear in mind, however, that this method version is sometimes unsafe, since pointers are required.

  • Si la aplicación debe convertir una gran cantidad de datos, debe volver a usar el búfer de salida.If your app must convert a large amount of data, it should reuse the output buffer. En este caso, el [], Int32, Int32, Char<xref:System.Text.Encoding.GetChars%28System.Byte%5B%5D%2CSystem.Int32%2CSystem.Int32%2CSystem.Char%5B%5D%2CSystem.Int32%29 > versión que admite caracteres de salida búferes es la mejor opción.In this case, the [], Int32, Int32, Char<xref:System.Text.Encoding.GetChars%28System.Byte%5B%5D%2CSystem.Int32%2CSystem.Int32%2CSystem.Char%5B%5D%2CSystem.Int32%29> version that supports output character buffers is the best choice.

  • Considere el uso de la Decoder.Convert método en lugar de GetCharCount.Consider using the Decoder.Convert method instead of GetCharCount. El método de conversión convierte tantos datos como sea posible y produce una excepción si el búfer de salida es demasiado pequeño.The conversion method converts as much data as possible and throws an exception if the output buffer is too small. Para la descodificación continua de un flujo, este método suele ser la mejor opción.For continuous decoding of a stream, this method is often the best choice.

Consulte también:

GetCharCount(ReadOnlySpan<Byte>) GetCharCount(ReadOnlySpan<Byte>) GetCharCount(ReadOnlySpan<Byte>) GetCharCount(ReadOnlySpan<Byte>)

public:
 virtual int GetCharCount(ReadOnlySpan<System::Byte> bytes);
public virtual int GetCharCount (ReadOnlySpan<byte> bytes);
abstract member GetCharCount : ReadOnlySpan<byte> -> int
override this.GetCharCount : ReadOnlySpan<byte> -> int
Public Overridable Function GetCharCount (bytes As ReadOnlySpan(Of Byte)) As Integer

Parámetros

Devoluciones

GetCharCount(Byte*, Int32) GetCharCount(Byte*, Int32) GetCharCount(Byte*, Int32)

Importante

Esta API no es conforme a CLS.

Cuando se reemplaza en una clase derivada, calcula el número de caracteres que se generan al descodificar una secuencia de bytes a partir del puntero de bytes especificado.When overridden in a derived class, calculates the number of characters produced by decoding a sequence of bytes starting at the specified byte pointer.

public:
 virtual int GetCharCount(System::Byte* bytes, int count);
[System.CLSCompliant(false)]
[System.Runtime.InteropServices.ComVisible(false)]
[System.Security.SecurityCritical]
public virtual int GetCharCount (byte* bytes, int count);
abstract member GetCharCount : nativeptr<byte> * int -> int
override this.GetCharCount : nativeptr<byte> * int -> int

Parámetros

bytes
Byte*

Puntero al primer byte que se va a descodificar.A pointer to the first byte to decode.

count
Int32 Int32 Int32 Int32

Número de bytes que se van a descodificar.The number of bytes to decode.

Devoluciones

Número de caracteres que se generan al descodificar la secuencia especificada de bytes.The number of characters produced by decoding the specified sequence of bytes.

Excepciones

Se ha producido una acción de reserva (vea Codificación de caracteres de .NET para obtener una explicación completa)A fallback occurred (see Character Encoding in .NET for complete explanation) - y --and- El valor de DecoderFallback está establecido en DecoderExceptionFallback.DecoderFallback is set to DecoderExceptionFallback.

Comentarios

La matriz exacta para calcular el tamaño que GetChars requiere para almacenar los caracteres resultantes, debe usar el GetCharCount método.To calculate the exact array size that GetChars requires to store the resulting characters, you should use the GetCharCount method. Para calcular el tamaño máximo de la matriz, use el GetMaxCharCount método.To calculate the maximum array size, use the GetMaxCharCount method. El GetCharCount método generalmente permite asignar menos memoria, mientras que el GetMaxCharCount método generalmente se ejecuta con mayor rapidez.The GetCharCount method generally allows allocation of less memory, while the GetMaxCharCount method generally executes faster.

El GetCharCount método determina el número de caracteres resultante de descodificar una secuencia de bytes y el GetChars método realiza la descodificación real.The GetCharCount method determines how many characters result in decoding a sequence of bytes, and the GetChars method performs the actual decoding. El GetChars método espera conversiones discretas, en contraposición al Decoder.GetChars método, que administra varios pasos en un único flujo de entrada.The GetChars method expects discrete conversions, in contrast to the Decoder.GetChars method, which handles multiple passes on a single input stream.

Varias versiones de GetCharCount y GetChars son compatibles.Several versions of GetCharCount and GetChars are supported. Éstas son algunas consideraciones de programación para su uso de estos métodos:The following are some programming considerations for use of these methods:

  • La aplicación deba descodificar varios bytes de entrada de una página de códigos y procesar los bytes mediante varias llamadas.Your app might need to decode multiple input bytes from a code page and process the bytes using multiple calls. En este caso, probablemente necesite mantener el estado entre llamadas.In this case, you probably need to maintain state between calls.

  • Si la aplicación administra los resultados de la cadena, se recomienda utilizar la GetString método.If your app handles string outputs, it is recommended to use the GetString method. Dado que este método debe comprobar la longitud de cadena y asignar un búfer, es algo más lento, pero resultante String tipo es preferible.Since this method must check string length and allocate a buffer, it is slightly slower, but the resulting String type is to be preferred.

  • La versión de bytes de GetChars(Byte*, Int32, Char*, Int32) permite algunas técnicas rápidas, especialmente con varias llamadas a los búferes grandes.The byte version of GetChars(Byte*, Int32, Char*, Int32) allows some fast techniques, particularly with multiple calls to large buffers. Tenga en cuenta, sin embargo, esta versión del método a veces es segura, puesto que los punteros son necesarios.Bear in mind, however, that this method version is sometimes unsafe, since pointers are required.

  • Si la aplicación debe convertir una gran cantidad de datos, debe volver a usar el búfer de salida.If your app must convert a large amount of data, it should reuse the output buffer. En este caso, el [], Int32, Int32, Char<xref:System.Text.Encoding.GetChars%28System.Byte%5B%5D%2CSystem.Int32%2CSystem.Int32%2CSystem.Char%5B%5D%2CSystem.Int32%29 > versión que admite caracteres de salida búferes es la mejor opción.In this case, the [], Int32, Int32, Char<xref:System.Text.Encoding.GetChars%28System.Byte%5B%5D%2CSystem.Int32%2CSystem.Int32%2CSystem.Char%5B%5D%2CSystem.Int32%29> version that supports output character buffers is the best choice.

  • Considere el uso de la Decoder.Convert método en lugar de GetCharCount.Consider using the Decoder.Convert method instead of GetCharCount. El método de conversión convierte tantos datos como sea posible y produce una excepción si el búfer de salida es demasiado pequeño.The conversion method converts as much data as possible and throws an exception if the output buffer is too small. Para la descodificación continua de un flujo, este método suele ser la mejor opción.For continuous decoding of a stream, this method is often the best choice.

Seguridad

SecurityCriticalAttribute
requiere plena confianza para el llamador inmediato.Requires full trust for the immediate caller. Este miembro no se puede usar código de confianza parcial o transparente.This member cannot be used by partially trusted or transparent code.

Consulte también:

GetCharCount(Byte[], Int32, Int32) GetCharCount(Byte[], Int32, Int32) GetCharCount(Byte[], Int32, Int32) GetCharCount(Byte[], Int32, Int32)

Cuando se reemplaza en una clase derivada, calcula el número de caracteres que se generan al descodificar una secuencia de bytes de la matriz de bytes especificada.When overridden in a derived class, calculates the number of characters produced by decoding a sequence of bytes from the specified byte array.

public:
 abstract int GetCharCount(cli::array <System::Byte> ^ bytes, int index, int count);
public abstract int GetCharCount (byte[] bytes, int index, int count);
abstract member GetCharCount : byte[] * int * int -> int
Public MustOverride Function GetCharCount (bytes As Byte(), index As Integer, count As Integer) As Integer

Parámetros

bytes
Byte[]

Matriz de bytes que contiene la secuencia de bytes que se va a descodificar.The byte array containing the sequence of bytes to decode.

index
Int32 Int32 Int32 Int32

Índice del primer byte que se va a descodificar.The index of the first byte to decode.

count
Int32 Int32 Int32 Int32

Número de bytes que se van a descodificar.The number of bytes to decode.

Devoluciones

Número de caracteres que se generan al descodificar la secuencia especificada de bytes.The number of characters produced by decoding the specified sequence of bytes.

Excepciones

index o count es menor que cero.index or count is less than zero.

O bien-or- index y count no denotan un intervalo válido en bytes.index and count do not denote a valid range in bytes.

Se ha producido una acción de reserva (vea Codificación de caracteres de .NET para obtener una explicación completa)A fallback occurred (see Character Encoding in .NET for complete explanation) - y --and- El valor de DecoderFallback está establecido en DecoderExceptionFallback.DecoderFallback is set to DecoderExceptionFallback.

Ejemplos

El ejemplo siguiente convierte una cadena de una codificación a otra.The following example converts a string from one encoding to another.

using namespace System;
using namespace System::Text;

int main()
{
   String^ unicodeString = "This string contains the unicode character Pi (\u03a0)";
   
   // Create two different encodings.
   Encoding^ ascii = Encoding::ASCII;
   Encoding^ unicode = Encoding::Unicode;
   
   // Convert the string into a byte array.
   array<Byte>^unicodeBytes = unicode->GetBytes( unicodeString );
   
   // Perform the conversion from one encoding to the other.
   array<Byte>^asciiBytes = Encoding::Convert( unicode, ascii, unicodeBytes );
   
   // Convert the new Byte into[] a char and[] then into a string.
   array<Char>^asciiChars = gcnew array<Char>(ascii->GetCharCount( asciiBytes, 0, asciiBytes->Length ));
   ascii->GetChars( asciiBytes, 0, asciiBytes->Length, asciiChars, 0 );
   String^ asciiString = gcnew String( asciiChars );
   
   // Display the strings created before and after the conversion.
   Console::WriteLine( "Original String*: {0}", unicodeString );
   Console::WriteLine( "Ascii converted String*: {0}", asciiString );
}
// The example displays the following output:
//    Original string: This string contains the unicode character Pi (Π)
//    Ascii converted string: This string contains the unicode character Pi (?)
using System;
using System.Text;

class Example
{
   static void Main()
   {
      string unicodeString = "This string contains the unicode character Pi (\u03a0)";

      // Create two different encodings.
      Encoding ascii = Encoding.ASCII;
      Encoding unicode = Encoding.Unicode;

      // Convert the string into a byte array.
      byte[] unicodeBytes = unicode.GetBytes(unicodeString);

      // Perform the conversion from one encoding to the other.
      byte[] asciiBytes = Encoding.Convert(unicode, ascii, unicodeBytes);
         
      // Convert the new byte[] into a char[] and then into a string.
      char[] asciiChars = new char[ascii.GetCharCount(asciiBytes, 0, asciiBytes.Length)];
      ascii.GetChars(asciiBytes, 0, asciiBytes.Length, asciiChars, 0);
      string asciiString = new string(asciiChars);

      // Display the strings created before and after the conversion.
      Console.WriteLine("Original string: {0}", unicodeString);
      Console.WriteLine("Ascii converted string: {0}", asciiString);
   }
}
// The example displays the following output:
//    Original string: This string contains the unicode character Pi (Π)
//    Ascii converted string: This string contains the unicode character Pi (?)
Imports System.Text

Class Example
   Shared Sub Main()
      Dim unicodeString As String = "This string contains the unicode character Pi (" & ChrW(&H03A0) & ")"

      ' Create two different encodings.
      Dim ascii As Encoding = Encoding.ASCII
      Dim unicode As Encoding = Encoding.Unicode

      ' Convert the string into a byte array.
      Dim unicodeBytes As Byte() = unicode.GetBytes(unicodeString)

      ' Perform the conversion from one encoding to the other.
      Dim asciiBytes As Byte() = Encoding.Convert(unicode, ascii, unicodeBytes)

      ' Convert the new byte array into a char array and then into a string.
      Dim asciiChars(ascii.GetCharCount(asciiBytes, 0, asciiBytes.Length)-1) As Char
      ascii.GetChars(asciiBytes, 0, asciiBytes.Length, asciiChars, 0)
      Dim asciiString As New String(asciiChars)

      ' Display the strings created before and after the conversion.
      Console.WriteLine("Original string: {0}", unicodeString)
      Console.WriteLine("Ascii converted string: {0}", asciiString)
   End Sub
End Class
' The example displays the following output:
'    Original string: This string contains the unicode character Pi (Π)
'    Ascii converted string: This string contains the unicode character Pi (?)

El ejemplo siguiente codifica una cadena en una matriz de bytes y, a continuación, descodifica un intervalo de bytes en una matriz de caracteres.The following example encodes a string into an array of bytes, and then decodes a range of the bytes into an array of characters.

using namespace System;
using namespace System::Text;
void PrintCountsAndChars( array<Byte>^bytes, int index, int count, 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, decode eight bytes starting at index 0,
   // and print out the counts and the resulting bytes.
   Console::Write( "BE array with BE encoding : " );
   PrintCountsAndChars( barrBE, 0, 8, u32BE );
   Console::Write( "LE array with LE encoding : " );
   PrintCountsAndChars( barrLE, 0, 8, u32LE );
}

void PrintCountsAndChars( array<Byte>^bytes, int index, int count, Encoding^ enc )
{
   
   // Display the name of the encoding used.
   Console::Write( "{0,-25} :", enc );
   
   // Display the exact character count.
   int iCC = enc->GetCharCount( bytes, index, count );
   Console::Write( " {0,-3}", iCC );
   
   // Display the maximum character count.
   int iMCC = enc->GetMaxCharCount( count );
   Console::Write( " {0,-3} :", iMCC );
   
   // Decode the bytes and display the characters.
   array<Char>^chars = enc->GetChars( bytes, index, count );
   
   // The following is an alternative way to decode the bytes:
   // Char[] chars = new Char[iCC];
   // enc->GetChars( bytes, index, count, chars, 0 );
   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 : 2   6   :za
LE array with LE encoding : System.Text.UTF32Encoding : 2   6   :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, decode eight bytes starting at index 0,
      // and print out the counts and the resulting bytes.
      Console.Write( "BE array with BE encoding : " );
      PrintCountsAndChars( barrBE, 0, 8, u32BE );
      Console.Write( "LE array with LE encoding : " );
      PrintCountsAndChars( barrLE, 0, 8, u32LE );

   }


   public static void PrintCountsAndChars( byte[] bytes, int index, int count, 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, index, count );
      Console.Write( " {0,-3}", iCC );

      // Display the maximum character count.
      int iMCC = enc.GetMaxCharCount( count );
      Console.Write( " {0,-3} :", iMCC );

      // Decode the bytes and display the characters.
      char[] chars = enc.GetChars( bytes, index, count );

      // The following is an alternative way to decode the bytes:
      // char[] chars = new char[iCC];
      // enc.GetChars( bytes, index, count, chars, 0 );

      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 : 2   6   :za
LE array with LE encoding : System.Text.UTF32Encoding : 2   6   :za

*/

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 barrBE 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 barrLE 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, decode eight bytes starting at index 0,
      ' and print out the counts and the resulting bytes.
      Console.Write("BE array with BE encoding : ")
      PrintCountsAndChars(barrBE, 0, 8, u32BE)
      Console.Write("LE array with LE encoding : ")
      PrintCountsAndChars(barrLE, 0, 8, u32LE)

   End Sub 'Main


   Public Shared Sub PrintCountsAndChars(bytes() As Byte, index As Integer, count As Integer, 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, index, count)
      Console.Write(" {0,-3}", iCC)

      ' Display the maximum character count.
      Dim iMCC As Integer = enc.GetMaxCharCount(count)
      Console.Write(" {0,-3} :", iMCC)

      ' Decode the bytes.
      Dim chars As Char() = enc.GetChars(bytes, index, count)

      ' The following is an alternative way to decode the bytes:
      ' 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 chars(iCC - 1) As Char
      ' enc.GetChars( bytes, index, count, chars, 0 )

      ' Display the characters.
      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 : 2   6   :za
'LE array with LE encoding : System.Text.UTF32Encoding : 2   6   :za

Comentarios

Para calcular el tamaño exacto de matriz requerido GetChars para almacenar los caracteres resultantes, debe usar el GetCharCount método.To calculate the exact array size required by GetChars to store the resulting characters, you should use the GetCharCount method. Para calcular el tamaño máximo de la matriz, use el GetMaxCharCount método.To calculate the maximum array size, use the GetMaxCharCount method. El GetCharCount método generalmente permite asignar menos memoria, mientras que el GetMaxCharCount método generalmente se ejecuta con mayor rapidez.The GetCharCount method generally allows allocation of less memory, while the GetMaxCharCount method generally executes faster.

El GetCharCount método determina el número de caracteres resultante de descodificar una secuencia de bytes y el GetChars método realiza la descodificación real.The GetCharCount method determines how many characters result in decoding a sequence of bytes, and the GetChars method performs the actual decoding. El GetChars método espera conversiones discretas, en contraposición al Decoder.GetChars método, que administra varios pasos en un único flujo de entrada.The GetChars method expects discrete conversions, in contrast to the Decoder.GetChars method, which handles multiple passes on a single input stream.

Varias versiones de GetCharCount y GetChars son compatibles.Several versions of GetCharCount and GetChars are supported. Éstas son algunas consideraciones de programación para su uso de estos métodos:The following are some programming considerations for use of these methods:

  • La aplicación deba descodificar varios bytes de entrada de una página de códigos y procesar los bytes mediante varias llamadas.Your app might need to decode multiple input bytes from a code page and process the bytes using multiple calls. En este caso, probablemente necesite mantener el estado entre llamadas.In this case, you probably need to maintain state between calls.

  • Si la aplicación administra los resultados de la cadena, se recomienda utilizar la GetString método.If your app handles string outputs, it is recommended to use the GetString method. Dado que este método debe comprobar la longitud de cadena y asignar un búfer, es algo más lento, pero resultante String tipo es preferible.Since this method must check string length and allocate a buffer, it is slightly slower, but the resulting String type is to be preferred.

  • La versión de bytes de GetChars(Byte*, Int32, Char*, Int32) permite algunas técnicas rápidas, especialmente con varias llamadas a los búferes grandes.The byte version of GetChars(Byte*, Int32, Char*, Int32) allows some fast techniques, particularly with multiple calls to large buffers. Tenga en cuenta, sin embargo, esta versión del método a veces es segura, puesto que los punteros son necesarios.Bear in mind, however, that this method version is sometimes unsafe, since pointers are required.

  • Si la aplicación debe convertir una gran cantidad de datos, debe volver a usar el búfer de salida.If your app must convert a large amount of data, it should reuse the output buffer. En este caso, el [], Int32, Int32, Char<xref:System.Text.Encoding.GetChars%28System.Byte%5B%5D%2CSystem.Int32%2CSystem.Int32%2CSystem.Char%5B%5D%2CSystem.Int32%29 > versión que admite caracteres de salida búferes es la mejor opción.In this case, the [], Int32, Int32, Char<xref:System.Text.Encoding.GetChars%28System.Byte%5B%5D%2CSystem.Int32%2CSystem.Int32%2CSystem.Char%5B%5D%2CSystem.Int32%29> version that supports output character buffers is the best choice.

  • Considere el uso de la Decoder.Convert método en lugar de GetCharCount.Consider using the Decoder.Convert method instead of GetCharCount. El método de conversión convierte tantos datos como sea posible y produce una excepción si el búfer de salida es demasiado pequeño.The conversion method converts as much data as possible and throws an exception if the output buffer is too small. Para la descodificación continua de un flujo, este método suele ser la mejor opción.For continuous decoding of a stream, this method is often the best choice.

Consulte también:

Se aplica a