UTF32Encoding::GetBytes Method (String^, Int32, Int32, array<Byte>^, Int32)
Encodes a set of characters from the specified String into the specified byte array.
Assembly: mscorlib (in mscorlib.dll)
public: virtual int GetBytes( String^ s, int charIndex, int charCount, array<unsigned char>^ bytes, int byteIndex ) override
Parameters
- s
-
Type:
System::String^
The String containing the set of characters to encode.
- charIndex
-
Type:
System::Int32
The index of the first character to encode.
- charCount
-
Type:
System::Int32
The number of characters to encode.
- bytes
-
Type:
array<System::Byte>^
The byte array to contain the resulting sequence of bytes.
- byteIndex
-
Type:
System::Int32
The index at which to start writing the resulting sequence of bytes.
| Exception | Condition |
|---|---|
| ArgumentNullException | s is null. -or- bytes is null. |
| ArgumentOutOfRangeException | charIndex or charCount or byteIndex is less than zero. -or- charIndex and charCount do not denote a valid range in chars. -or- byteIndex is not a valid index in bytes. |
| ArgumentException | Error detection is enabled, and s contains an invalid sequence of characters. -or- bytes does not have enough capacity from byteIndex to the end of the array to accommodate the resulting bytes. |
| EncoderFallbackException | A fallback occurred (see Character Encoding in the .NET Framework for complete explanation) -and- EncoderFallback is set to EncoderExceptionFallback. |
To calculate the exact array size required by GetBytes to store the resulting bytes, you call the GetByteCount method. To calculate the maximum array size, you call the GetMaxByteCount method. The GetByteCount method generally allocates less memory, while the GetMaxByteCount method generally executes faster.
With error detection, an invalid sequence causes this method to throw a ArgumentException. Without error detection, invalid sequences are ignored, and no exception is thrown.
Data to be converted, such as data read from a stream, might be available only in sequential blocks. In this case, or if the amount of data is so large that it needs to be divided into smaller blocks, the application uses the Decoder or the Encoder provided by the GetDecoder method or the GetEncoder method, respectively.
Note |
|---|
To ensure that the encoded bytes are decoded properly when they are saved as a file or as a stream, you can prefix a stream of encoded bytes with a preamble. Inserting a preamble at the beginning of a byte stream (such as at the beginning of a series of bytes to be written to a file) is the developer's responsibility. The GetBytes method does not prepend a preamble to the beginning of a sequence of encoded bytes. |
The following example determines the number of bytes required to encode a string, then encodes the string and displays the resulting bytes.
using namespace System; using namespace System::Text; void PrintCountsAndBytes( String^ s, 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) String^ myStr = L"za\u0306\u01FD\u03B2\xD8FF\xDCFF"; // Create instances of different encodings. UTF7Encoding^ u7 = gcnew UTF7Encoding; UTF8Encoding^ u8Nobom = gcnew UTF8Encoding( false,true ); UTF8Encoding^ u8Bom = gcnew UTF8Encoding( true,true ); UTF32Encoding ^ u32Nobom = gcnew UTF32Encoding( false,false,true ); UTF32Encoding ^ u32Bom = gcnew UTF32Encoding( false,true,true ); // Get the byte counts and the bytes. PrintCountsAndBytes( myStr, u7 ); PrintCountsAndBytes( myStr, u8Nobom ); PrintCountsAndBytes( myStr, u8Bom ); PrintCountsAndBytes( myStr, u32Nobom ); PrintCountsAndBytes( myStr, u32Bom ); } void PrintCountsAndBytes( String^ s, Encoding^ enc ) { // Display the name of the encoding used. Console::Write( "{0,-25} :", enc ); // Display the exact byte count. int iBC = enc->GetByteCount( s ); Console::Write( " {0,-3}", iBC ); // Display the maximum byte count. int iMBC = enc->GetMaxByteCount( s->Length ); Console::Write( " {0,-3} :", iMBC ); // Get the byte order mark, if any. array<Byte>^preamble = enc->GetPreamble(); // Combine the preamble and the encoded bytes. array<Byte>^bytes = gcnew array<Byte>(preamble->Length + iBC); Array::Copy( preamble, bytes, preamble->Length ); enc->GetBytes( s, 0, s->Length, bytes, preamble->Length ); // 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 : 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.UTF8Encoding : 12 24 :EF BB BF 7A 61 CC 86 C7 BD CE B2 F1 8F B3 BF System.Text.UTF32Encoding : 24 28 :7A 00 00 00 61 00 00 00 06 03 00 00 FD 01 00 00 B2 03 00 00 FF FC 04 00 System.Text.UTF32Encoding : 24 28 :FF FE 00 00 7A 00 00 00 61 00 00 00 06 03 00 00 FD 01 00 00 B2 03 00 00 FF FC 04 00 */
Available since 10
.NET Framework
Available since 2.0
