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Encoding::GetByteCount Method (array<Char>)

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

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

virtual int GetByteCount(
	array<wchar_t>^ chars


Type: array<System::Char>
The character array containing the characters to encode.

Return Value

Type: System::Int32
The number of bytes produced by encoding all the characters in the specified character array.


chars is nullptr.


A fallback occurred (see Character Encoding in the .NET Framework for complete explanation)


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.

The GetByteCount method determines how many bytes result in encoding a set of Unicode characters, and the GetBytes method performs the actual encoding. The GetBytes method expects discrete conversions, in contrast to the Encoder::GetBytes method, which handles multiple conversions on a single input stream.

Several versions of GetByteCount and GetBytes are supported. The following are some programming considerations for use of these methods:

  • The application might need to encode many input characters to a code page and process the characters using multiple calls. In this case, your application probably needs to maintain state between calls, taking into account the state that is persisted by the Encoder object being used.

  • If the application handles string inputs, it is recommended to use the string version of GetBytes.

  • The Unicode character buffer version of GetBytes allows some fast techniques, particularly with multiple calls using the Encoder object or inserting into existing buffers. Bear in mind, however, that this method version is sometimes unsafe, since pointers are required.

  • If your application must convert a large amount of data, it should reuse the output buffer. In this case, the GetBytes version that supports byte arrays is the best choice.

  • Consider using the Encoder::Convert method instead of GetByteCount. The conversion method converts as much data as possible, and does throw an exception if the output buffer is too small. For continuous encoding of a stream, this method is often the best choice.

The following example determines the number of bytes required to encode a character array, encodes the characters, and displays the resulting bytes.

using namespace System;
using namespace System::Text;
void PrintCountsAndBytes( array<Char>^chars, 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>{

   // Get different encodings.
   Encoding^ u7 = Encoding::UTF7;
   Encoding^ u8 = Encoding::UTF8;
   Encoding^ u16LE = Encoding::Unicode;
   Encoding^ u16BE = Encoding::BigEndianUnicode;
   Encoding^ u32 = Encoding::UTF32;

   // Encode the entire array, and print out the counts and the resulting bytes.
   PrintCountsAndBytes( myChars, u7 );
   PrintCountsAndBytes( myChars, u8 );
   PrintCountsAndBytes( myChars, u16LE );
   PrintCountsAndBytes( myChars, u16BE );
   PrintCountsAndBytes( myChars, u32 );

void PrintCountsAndBytes( array<Char>^chars, Encoding^ enc )

   // Display the name of the encoding used.
   Console::Write( "{0,-30} :", enc );

   // Display the exact byte count.
   int iBC = enc->GetByteCount( chars );
   Console::Write( " {0,-3}", iBC );

   // Display the maximum byte count.
   int iMBC = enc->GetMaxByteCount( chars->Length );
   Console::Write( " {0,-3} :", iMBC );

   // Encode the array of chars.
   array<Byte>^bytes = enc->GetBytes( chars );

   // Display all the encoded bytes.
   PrintHexBytes( bytes );

void PrintHexBytes( array<Byte>^bytes )
   if ( (bytes == nullptr) || (bytes->Length == 0) )
      Console::WriteLine( "<none>" );
      for ( int i = 0; i < bytes->Length; i++ )
         Console::Write( "{0:X2} ", bytes[ i ] );

This code produces the following output.

System.Text.UTF7Encoding       : 18  23  :7A 61 2B 41 77 59 42 2F 51 4F 79 32 50 2F 63 2F 77 2D
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
System.Text.UTF32Encoding      : 24  32  :7A 00 00 00 61 00 00 00 06 03 00 00 FD 01 00 00 B2 03 00 00 FF FC 04 00


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.