GetMaxByteCount

Calculates the maximum number of bytes produced by encoding the specified number of characters.

 Public Function GetMaxByteCount(
	  ByVal CharCount As Long ) As Long

Parameters

CharCount

[ByVal] Long. The number of characters to encode.

Return Values

Remarks

To calculate the exact array size required by GetBytesEx to store the resulting bytes, the application uses 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.

GetMaxByteCount is a worst-case number, including the worst case for the currently selected EncoderFallback. If a fallback is chosen with a potentially large string, GetMaxByteCount can return large values.

In most cases, this method returns reasonable numbers for small strings. For large strings, you might have to choose between using very large buffers and catching errors in the rare case that a more reasonable buffer is exceeded. You might also want to consider a different approach using GetByteCount or Encoder.Convert. For example, text in English and many other languages often needs only one UTF-8 byte to represent a character, but the number returned by GetMaxByteCount has to allow for the possibility that the string to be converted will consist entirely of characters that each require four bytes.

GetMaxByteCount has no relation to GetCharsEx. If your application needs a similar function to use with GetCharsEx, it should use GetMaxCharCount.

Exceptions

Exception	Condition
ArgumentOutOfRangeException	CharCount is less than zero. -or- The resulting number of bytes is greater than the maximum number that can be returned as an integer.
EncoderFallbackException	A fallback occurred -and- EncoderFallback is set to EncoderFallbackException.

Examples

The following example demonstrates how to use the GetMaxByteCount method to return the maximum number of bytes required to encode a specified number of characters.

Public Sub Main()
    Const CharCount As Long = 2
    
    Dim UTF8 As New UTF8Encoding
    Dim MaxByteCount As Long
    
    MaxByteCount = UTF8.GetMaxByteCount(CharCount)
    
    Console.WriteLine "Maximum of {0} bytes needed to encode {1} characters.", MaxByteCount, CharCount
    Console.ReadKey
End Sub

' This code produces the following output.
'
'   Maximum of 9 bytes needed to encode 2 characters.

See Also

Project CorLib Overview

Class UTF8Encoding Overview

GetBytesEx

GetByteCount

GetEncoder