GetMaxByteCount Method

UTF8Encoding.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
)
public int GetMaxByteCount (
	int charCount
)
public override function GetMaxByteCount (
	charCount : int
) : int
Not applicable.

Parameters

charCount

The number of characters to encode.

Return Value

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

Exception typeCondition

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 Understanding Encodings for complete 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 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 System.Text.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 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 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 UTF8EncodingExample {
    public static void Main() {
        UTF8Encoding utf8 = new UTF8Encoding();
        int charCount = 2;
        int maxByteCount = utf8.GetMaxByteCount(charCount);
        Console.WriteLine(
            "Maximum of {0} bytes needed to encode {1} characters.",
            maxByteCount,
            charCount
        );
    }
}

import System.*;
import System.Text.*;

class UTF8EncodingExample
{
    public static void main(String[] args)
    {
        UTF8Encoding utf8 = new UTF8Encoding();
        int charCount = 2;
        int maxByteCount = utf8.GetMaxByteCount(charCount);

        Console.WriteLine(
            "Maximum of {0} bytes needed to encode {1} characters.", 
            String.valueOf(maxByteCount), String.valueOf(charCount));
    } //main
} //UTF8EncodingExample

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

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