To calculate the exact array size required by Encoding.GetChars(Byte[]) to store the resulting characters, the application should use Encoding.GetCharCount(Byte[]). To calculate the maximum array size, the application should use Encoding.GetMaxCharCount(int). The Encoding.GetCharCount(Byte[]) method generally allows allocation of less memory, while the Encoding.GetMaxCharCount(int) method generally executes faster.

The Encoding.GetCharCount(Byte[]) method determines how many characters result in decoding a sequence of bytes, and the Encoding.GetChars(Byte[]) method performs the actual decoding. The Encoding.GetChars(Byte[]) method expects discrete conversions, in contrast to the Decoder.GetChars(Byte[], int, int, Char[], int) method, which handles multiple passes on a single input stream.

Several versions of Encoding.GetCharCount(Byte[]) and Encoding.GetChars(Byte[]) are supported. The following are some programming considerations for use of these methods:

• The application might need to decode multiple input bytes from a code page and process the bytes using multiple calls. In this case, your application probably needs to maintain state between calls.

• If the application handles string outputs, it is recommended to use the Encoding.GetString(Byte[]) method. Since this method must check string length and allocate a buffer, it is slightly slower, but the resulting string type is to be preferred.

• The byte version of Encoding.GetChars(Byte*, int, Char*, int) allows some fast techniques, particularly with multiple calls to large 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 Encoding.GetChars(Byte[], int, int, Char[], int) version that supports output character buffers is the best choice.

• Consider using the erload:System.Text.Decoder.Convert method instead of Encoding.GetCharCount(Byte[]). The conversion method converts as much data as possible and throws an exception if the output buffer is too small. For continuous decoding of a stream, this method is often the best choice.

Namespace: System.Text
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0, 4.0.0.0