UnicodeEncoding.GetMaxByteCount Method

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

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

public override int GetMaxByteCount(
	int charCount
)

Parameters

charCount
Type: System.Int32

The number of characters to encode.

Return Value

Type: System.Int32
The maximum number of bytes produced by encoding the specified number of characters.

ExceptionCondition
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 (see Character Encoding in the .NET Framework for fuller explanation)

-and-

EncoderFallback is set to EncoderExceptionFallback.

To calculate the exact array size required by GetBytes 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 retrieves 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 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 exceeded. You might also want to consider a different approach using GetByteCount or Encoder.Convert.

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

NoteNote

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

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

using System;
using System.Text;

class UnicodeEncodingExample {
    public static void Main() {
        UnicodeEncoding Unicode = new UnicodeEncoding();
        int charCount = 2;
        int maxByteCount = Unicode.GetMaxByteCount(charCount);
        Console.WriteLine(
            "Maximum of {0} bytes needed to encode {1} characters.",
            maxByteCount,
            charCount
        );
    }
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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