Decoder.GetCharCount Method (Byte[], Int32, Int32)

 

When overridden in a derived class, calculates the number of characters produced by decoding a sequence of bytes from the specified byte array.

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

public abstract int GetCharCount(
	byte[] bytes,
	int index,
	int count
)

Parameters

bytes
Type: System.Byte[]

The byte array containing the sequence of bytes to decode.

index
Type: System.Int32

The index of the first byte to decode.

count
Type: System.Int32

The number of bytes to decode.

Return Value

Type: System.Int32

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

-and-

Fallback is set to DecoderExceptionFallback.

This method does not affect the state of the decoder.

To calculate the exact array size that GetChars requires to store the resulting characters, the application should use GetCharCount.

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.

using System;
using System.Text;

class DecoderExample {
    public static void Main() {
        Byte[] bytes = new Byte[] {
            85, 0, 110, 0, 105, 0, 99, 0, 111, 0, 100, 0, 101, 0
        };

        Decoder uniDecoder = Encoding.Unicode.GetDecoder();
        int charCount = uniDecoder.GetCharCount(bytes, 0, bytes.Length);
        Console.WriteLine(
            "{0} characters needed to decode bytes.", charCount
        );
    }
}

/* This code example produces the following output.

7 characters needed to decode bytes.

*/

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
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