Encoding::GetByteCount Method (Char*, Int32)
When overridden in a derived class, calculates the number of bytes produced by encoding a set of characters starting at the specified character pointer.
Assembly: mscorlib (in mscorlib.dll)
[ComVisibleAttribute(false)] [CLSCompliantAttribute(false)] public: virtual int GetByteCount( wchar_t* chars, int count )
Parameters
- chars
- Type: System::Char*
A pointer to the first character to encode.
- count
- Type: System::Int32
The number of characters to encode.
| Exception | Condition |
|---|---|
| ArgumentNullException | chars is nullptr. |
| ArgumentOutOfRangeException | count is less than zero. |
| EncoderFallbackException | A fallback occurred (see Understanding Encodings for complete explanation) -and- EncoderFallback is set to EncoderExceptionFallback. |
To calculate the exact array size that GetBytes requires 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 Encoding::GetBytes method performs the actual encoding. The GetBytes method expects discrete conversions, in contrast to the 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 Encoding::GetBytes(String).
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 Encoding::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.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.