UTF8Encoding.GetCharCount Method

Definition

Namespace:

System.Text

Assembly:

System.Text.Encoding.Extensions.dll

Calculates the number of characters produced by decoding a sequence of bytes.

Overloads

GetCharCount(Byte[], Int32, Int32)	Calculates the number of characters produced by decoding a sequence of bytes from the specified byte array.
GetCharCount(Byte*, Int32)	Calculates the number of characters produced by decoding a sequence of bytes starting at the specified byte pointer.
GetCharCount(ReadOnlySpan<Byte>)	Calculates the number of characters produced by decoding the specified byte span.

GetCharCount(Byte[], Int32, Int32)

Source:

UTF8Encoding.cs

Calculates the number of characters produced by decoding a sequence of bytes from the specified byte array.

public:
 override int GetCharCount(cli::array <System::Byte> ^ bytes, int index, int count);

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

override this.GetCharCount : byte[] * int * int -> int

Public Overrides Function GetCharCount (bytes As Byte(), index As Integer, count As Integer) As Integer

Parameters

bytes

Byte[]

The byte array containing the sequence of bytes to decode.

index

Int32

The index of the first byte to decode.

count

Int32

The number of bytes to decode.

Returns

Int32

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

Exceptions

ArgumentNullException

bytes is null.

ArgumentOutOfRangeException

index or count is less than zero.

-or-

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

-or-

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

ArgumentException

Error detection is enabled, and bytes contains an invalid sequence of bytes.

DecoderFallbackException

A fallback occurred (for more information, see Character Encoding in .NET)

-and-

DecoderFallback is set to DecoderExceptionFallback.

Examples

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

using namespace System;
using namespace System::Text;
int main()
{
   array<Byte>^bytes = {85,84,70,56,32,69,110,99,111,100,105,110,103,32,69,120,97,109,112,108,101};
   UTF8Encoding^ utf8 = gcnew UTF8Encoding;
   int charCount = utf8->GetCharCount( bytes, 2, 8 );
   Console::WriteLine( "{0} characters needed to decode bytes.", charCount );
}

using System;
using System.Text;

class UTF8EncodingExample {
    public static void Main() {
        Byte[] bytes = new Byte[] {
             85,  84,  70,  56,  32,  69, 110,
             99, 111, 100, 105, 110, 103,  32,
             69, 120,  97, 109, 112, 108, 101
        };

        UTF8Encoding utf8 = new UTF8Encoding();
        int charCount = utf8.GetCharCount(bytes, 2, 8);
        Console.WriteLine(
            "{0} characters needed to decode bytes.", charCount
        );
    }
}

Imports System.Text

Class UTF8EncodingExample
    
    Public Shared Sub Main()
        Dim bytes() As Byte = { _
            85,  84,  70,  56,  32,  69, 110, _
            99, 111, 100, 105, 110, 103,  32, _
            69, 120,  97, 109, 112, 108, 101 _
        }
        
        Dim utf8 As New UTF8Encoding()
        Dim charCount As Integer = utf8.GetCharCount(bytes, 2, 8)
        Console.WriteLine("{0} characters needed to decode bytes.", charCount)
    End Sub
End Class

Remarks

To calculate the exact array size required by GetChars to store the resulting characters, call the GetCharCount method. To calculate the maximum array size, call the GetMaxCharCount method. The GetCharCount method generally allocates less memory, while the GetMaxCharCount method generally executes faster.

With error detection, an invalid sequence causes this method to throw an ArgumentException exception. Without error detection, invalid sequences are ignored, and no exception is thrown.

See also

• GetChars
• GetMaxCharCount(Int32)
• GetDecoder()

GetCharCount(Byte*, Int32)

Source:

UTF8Encoding.cs

Important

This API is not CLS-compliant.

Calculates the number of characters produced by decoding a sequence of bytes starting at the specified byte pointer.

public:
 override int GetCharCount(System::Byte* bytes, int count);

[System.CLSCompliant(false)]
public override int GetCharCount (byte* bytes, int count);

[<System.CLSCompliant(false)>]
override this.GetCharCount : nativeptr<byte> * int -> int

Parameters

bytes

Byte*

A pointer to the first byte to decode.

count

Int32

The number of bytes to decode.

Returns

Int32

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

Attributes

CLSCompliantAttribute

Exceptions

ArgumentNullException

bytes is null.

ArgumentOutOfRangeException

count is less than zero.

-or-

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

ArgumentException

Error detection is enabled, and bytes contains an invalid sequence of bytes.

DecoderFallbackException

A fallback occurred (for more information, see Character Encoding in .NET)

-and-

DecoderFallback is set to DecoderExceptionFallback.

Remarks

To calculate the exact array size required by GetChars to store the resulting characters, call the GetCharCount method. To calculate the maximum array size, call the GetMaxCharCount method. The GetCharCount method generally allocates less memory, while the GetMaxCharCount method generally executes faster.

With error detection, an invalid sequence causes this method to throw an ArgumentException exception. Without error detection, invalid sequences are ignored, and no exception is thrown.

See also

• GetChars
• GetMaxCharCount(Int32)
• GetDecoder()

GetCharCount(ReadOnlySpan<Byte>)

Source:

UTF8Encoding.cs

Calculates the number of characters produced by decoding the specified byte span.

public:
 override int GetCharCount(ReadOnlySpan<System::Byte> bytes);

public override int GetCharCount (ReadOnlySpan<byte> bytes);

override this.GetCharCount : ReadOnlySpan<byte> -> int

Public Overrides Function GetCharCount (bytes As ReadOnlySpan(Of Byte)) As Integer

Parameters

bytes

ReadOnlySpan<Byte>

The span containing the set of bytes to decode.

Returns

Int32

The number of characters produced by decoding the specified byte span.

Remarks

To calculate the exact size required by GetChars to store the resulting characters, call the GetCharCount method. To calculate the maximum size, call the GetMaxCharCount method. The GetCharCount method generally allocates less memory, while the GetMaxCharCount method generally executes faster.

With error detection, an invalid sequence causes this method to throw an ArgumentException exception. Without error detection, invalid sequences are ignored, and no exception is thrown.