Decoder.GetCharCount Method (Byte(), Int32, Int32)
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
When overridden in a derived class, calculates the number of characters produced by decoding a sequence of bytes from the specified byte array.
Assembly: mscorlib (in mscorlib.dll)
'Declaration Public MustOverride Function GetCharCount ( _ bytes As Byte(), _ index As Integer, _ count As Integer _ ) As Integer
Parameters
- bytes
- Type:
System.Byte
()
The byte array containing the sequence of bytes to decode.
- index
- Type: System.Int32
The zero-based index of the first byte to decode.
- count
- Type: System.Int32
The number of bytes to decode.
Return Value
Type: System.Int32The number of characters produced by decoding the specified sequence of bytes and any bytes in the internal buffer.
| Exception | Condition |
|---|---|
| ArgumentNullException | bytes is null (Nothing). |
| ArgumentOutOfRangeException | index or count is less than zero. -or- index and count do not denote a valid range in bytes. |
| DecoderFallbackException | A fallback occurred. |
This method does not affect the state of the decoder.
The GetCharCount(Byte(), Int32, Int32) method calculates the exact array size that the GetChars method requires to store the decoded characters.
If GetChars is called with flush set to false, the decoder stores trailing bytes at the end of the data block in an internal buffer and uses them in the next decoding operation. The application should call GetCharCount on a block of data immediately before calling GetChars on the same block, so that any trailing bytes from the previous block are included in the calculation.
The following code example demonstrates how to use the GetCharCount method to calculate the number of characters required to decode the specified range of bytes in the array.
Imports System.Text Class Example Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock) Dim bytes() As Byte = { _ 85, 0, 110, 0, 105, 0, 99, 0, 111, 0, 100, 0, 101, 0 _ } Dim uniDecoder As Decoder = Encoding.Unicode.GetDecoder() Dim charCount As Integer = uniDecoder.GetCharCount(bytes, 0, bytes.Length) outputBlock.Text += String.Format("{0} characters needed to decode bytes.", charCount) & vbCrLf End Sub End Class