Encoding.GetMaxCharCount Method (Int32)

 

When overridden in a derived class, calculates the maximum number of characters produced by decoding the specified number of bytes.

Namespace:   System.Text
Assembly:  mscorlib (in mscorlib.dll)

abstract GetMaxCharCount : 
        byteCount:int -> int

Parameters

byteCount
Type: System.Int32

The number of bytes to decode.

Return Value

Type: System.Int32

The maximum number of characters produced by decoding the specified number of bytes.

Exception Condition
ArgumentOutOfRangeException

byteCount is less than zero.

DecoderFallbackException

A fallback occurred (see Character Encoding in the .NET Framework for complete explanation)

-and-

DecoderFallback is set to DecoderExceptionFallback.

To calculate the exact array size required by GetChars to store the resulting characters, you should use the GetCharCount method. To calculate the maximum array size, use the GetMaxCharCount method. The GetCharCount method generally allows allocation of less memory, while the GetMaxCharCount method generally executes faster.

GetMaxCharCount retrieves a worst-case number, including the worst case for the currently selected DecoderFallback. If a fallback is chosen with a potentially large string, GetMaxCharCount retrieves large values.

In most cases, this method retrieves 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 too small. You might also want to consider a different approach using GetCharCount or Decoder.Convert.

GetMaxCharCount has no relation to GetBytes. If you needs a similar function to use with GetBytes, you should use GetMaxByteCount.

When using GetMaxCharCount, you should allocate the output buffer based on the maximum size of the input buffer. If the output buffer is constrained in size, you might use the Decoder.Convert method.

Note that GetMaxCharCount considers the worst case for leftover bytes from a previous encoder operation. For most code pages, passing a value of 0 to this method retrieves values greater than or equal to 1.

System_CAPS_noteNote

GetMaxCharCount(N) is not necessarily the same value as N* GetMaxCharCount(1).

Notes to Implementers:

All Encoding implementations must guarantee that no buffer overflow exceptions occur if buffers are sized according to the results of this method's calculations.

The following example encodes a string into an array of bytes, and then decodes the bytes into an array of characters.

No code example is currently available or this language may not be supported.

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
Return to top
Show: