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


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 override int GetCharCount(
	byte[] bytes,
	int index,
	int count


Type: System.Byte[]

The byte array containing the sequence of bytes to decode.

Type: System.Int32

The index of the first byte to decode.

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.

Exception Condition

bytes is null.


index or count is less than zero.


index and count do not denote a valid range in bytes.


The resulting number of bytes is greater than the maximum number that can be returned as an integer.


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


DecoderFallback is set to DecoderExceptionFallback.

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

The following example demonstrates how to use the GetCharCount method to return the number of characters produced by decoding a range of elements in a byte array.

using System;
using System.Text;

class ASCIIEncodingExample {
    public static void Main() {
        Byte[] bytes = new Byte[] {
             65,  83,  67,  73,  73,  32,  69,
            110,  99, 111, 100, 105, 110, 103,
             32,  69, 120,  97, 109, 112, 108, 101

        ASCIIEncoding ascii = new ASCIIEncoding();
        int charCount = ascii.GetCharCount(bytes, 6, 8);
            "{0} characters needed to decode bytes.", charCount

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Return to top
Was this page helpful?
(1500 characters remaining)
Thank you for your feedback
© 2015 Microsoft