EncoderFallbackException
Class
Definition
The exception that is thrown when an encoder fallback operation fails. This class cannot be inherited.
public sealed class EncoderFallbackException : ArgumentException
- Inheritance
Inherited Members
System.ArgumentException
System.Exception
System.Object
Examples
The following code example demonstrates the EncoderExceptionFallback and EncoderFallbackException classes.
// This example demonstrates the EncoderExceptionFallback class.
using namespace System;
using namespace System::Text;
int main()
{
// Create an encoding, which is equivalent to calling the
// ASCIIEncoding class constructor.
// The EncoderExceptionFallback parameter causes an exception to
// be thrown when a character cannot be encoded.
// A decoder exception fallback is also specified, but it is not
// used because this example terminates during the encoding operation.
Encoding^ asciiEncoding = Encoding::GetEncoding("us-ascii",
gcnew EncoderExceptionFallback(), gcnew DecoderExceptionFallback());
// The input string consists of the Unicode characters LEFT POINTING
// DOUBLE ANGLE QUOTATION MARK (U+00AB), 'X' (U+0058), and RIGHT
// POINTING DOUBLE ANGLE QUOTATION MARK (U+00BB).
// The encoding can only encode characters in the US-ASCII range of
// U+0000 through U+007F. Consequently, the characters bracketing the
// 'X' character cause an exception.
String^ inputString = L"\u00abX\u00bb";
String^ twoNewLines = Environment::NewLine + Environment::NewLine;
array<Byte>^ encodedBytes = gcnew array<Byte>(
asciiEncoding->GetMaxByteCount(inputString->Length));
int numberOfEncodedBytes = 0;
// ---------------------------------------------------------------------
Console::Clear();
// Display the name of the encoding.
Console::WriteLine("The name of the encoding is \"{0}\".{1}",
asciiEncoding->WebName, Environment::NewLine);
// Display the input string in text.
Console::WriteLine("Input string ({0} characters): \"{1}\"",
inputString->Length, inputString);
// Display the input string in hexadecimal.
Console::Write("Input string in hexadecimal: ");
for each (char c in inputString)
{
Console::Write("0x{0:X2} ", c);
}
Console::Write(twoNewLines);
// ---------------------------------------------------------------------
// Attempt to encode the input string. However, an exception is thrown
// before the input string can be encoded.
Console::WriteLine("Encode the input string...");
// The code example terminates during the call to the GetBytes() method.
try
{
numberOfEncodedBytes = asciiEncoding->GetBytes(inputString, 0,
inputString->Length, encodedBytes, 0);
// This statement is never executed.
Console::WriteLine("This statement is never executed.");
}
catch (EncoderFallbackException^ ex)
{
Console::WriteLine(ex);
Console::WriteLine(
"{0}*** THE CODE EXAMPLE TERMINATES HERE AS INTENDED. ***",
Environment::NewLine);
}
}
/*
This code example produces the following results:
The name of the encoding is "us-ascii".
Input string (3 characters): "X"
Input string in hexadecimal: 0xAB 0x58 0xBB
Encode the input string...
System.Text.EncoderFallbackException: Unable to translate Unicode character \u00AB at inde
x 0 to specified code page.
at System.Text.EncoderExceptionFallbackBuffer.Fallback(Char charUnknown, Int32 index)
at System.Text.EncoderFallbackBuffer.InternalFallback(Char ch, Char*& chars)
at System.Text.ASCIIEncoding.GetBytes(Char* chars, Int32 charCount, Byte* bytes, Int32
byteCount, EncoderNLS encoder)
at System.Text.ASCIIEncoding.GetBytes(String chars, Int32 charIndex, Int32 charCount, B
yte[] bytes, Int32 byteIndex)
at Sample.Main()
*** THE CODE EXAMPLE TERMINATES HERE AS INTENDED. ***
*/
// This example demonstrates the EncoderExceptionFallback class.
using System;
using System.Text;
class Sample
{
public static void Main()
{
// Create an encoding, which is equivalent to calling the
// ASCIIEncoding class constructor.
// The EncoderExceptionFallback parameter causes an exception to
// be thrown when a character cannot be encoded.
// A decoder exception fallback is also specified, but it is not
// used because this example terminates during the encoding operation.
Encoding ae = Encoding.GetEncoding(
"us-ascii",
new EncoderExceptionFallback(),
new DecoderExceptionFallback());
// The input string consists of the Unicode characters LEFT POINTING
// DOUBLE ANGLE QUOTATION MARK (U+00AB), 'X' (U+0058), and RIGHT POINTING
// DOUBLE ANGLE QUOTATION MARK (U+00BB).
// The encoding can only encode characters in the US-ASCII range of U+0000
// through U+007F. Consequently, the characters bracketing the 'X' character
// cause an exception.
string inputString = "\u00abX\u00bb";
string twoNewLines = "\n\n";
byte[] encodedBytes = new byte[ae.GetMaxByteCount(inputString.Length)];
int numberOfEncodedBytes = 0;
// --------------------------------------------------------------------------
Console.Clear();
// Display the name of the encoding.
Console.WriteLine("The name of the encoding is \"{0}\".\n", ae.WebName);
// Display the input string in text.
Console.WriteLine("Input string ({0} characters): \"{1}\"",
inputString.Length, inputString);
// Display the input string in hexadecimal.
Console.Write("Input string in hexadecimal: ");
foreach (char c in inputString.ToCharArray()) {
Console.Write("0x{0:X2} ", (int)c);}
Console.Write(twoNewLines);
// --------------------------------------------------------------------------
// Attempt to encode the input string. However, an exception is thrown before
// the input string can be encoded.
Console.WriteLine("Encode the input string...");
// The code example terminates during the call to the GetBytes() method.
try {
numberOfEncodedBytes = ae.GetBytes(inputString, 0, inputString.Length,
encodedBytes, 0);
}
catch (EncoderFallbackException e)
{
Console.WriteLine(e);
Console.WriteLine("\n*** THE CODE EXAMPLE TERMINATES HERE AS INTENDED. ***");
return;
}
// This statement is never executed.
Console.WriteLine("This statement is never executed.");
}
}
/*
This code example produces the following results:
The name of the encoding is "us-ascii".
Input string (3 characters): "�X�"
Input string in hexadecimal: 0xAB 0x58 0xBB
Encode the input string...
System.Text.EncoderFallbackException: Unable to translate Unicode character \u00AB at inde
x 0 to specified code page.
at System.Text.EncoderExceptionFallbackBuffer.Fallback(Char charUnknown, Int32 index)
at System.Text.EncoderFallbackBuffer.InternalFallback(Char ch, Char*& chars)
at System.Text.ASCIIEncoding.GetBytes(Char* chars, Int32 charCount, Byte* bytes, Int32
byteCount, EncoderNLS encoder)
at System.Text.ASCIIEncoding.GetBytes(String chars, Int32 charIndex, Int32 charCount, B
yte[] bytes, Int32 byteIndex)
at Sample.Main()
*** THE CODE EXAMPLE TERMINATES HERE AS INTENDED. ***
*/
' This example demonstrates the EncoderExceptionFallback class.
Imports System
Imports System.Text
Class Sample
Public Shared Sub Main()
' Create an encoding, which is equivalent to calling the
' ASCIIEncoding class constructor.
' The EncoderExceptionFallback parameter causes an exception to
' be thrown when a character cannot be encoded.
' A decoder exception fallback is also specified, but it is not
' used because this example terminates during the encoding operation.
Dim eef As New EncoderExceptionFallback()
Dim def As New DecoderExceptionFallback()
Dim ae As Encoding = Encoding.GetEncoding("us-ascii", eef, def)
' The input string consists of the Unicode characters LEFT POINTING
' DOUBLE ANGLE QUOTATION MARK (U+00AB), 'X' (U+0058), and RIGHT POINTING
' DOUBLE ANGLE QUOTATION MARK (U+00BB).
' The encoding can only encode characters in the US-ASCII range of U+0000
' through U+007F. Consequently, the characters bracketing the 'X' character
' cause an exception.
Dim inputString As String = "«X»"
Dim twoNewLines As String = vbCrLf & vbCrLf
Dim numberOfEncodedBytes As Integer = ae.GetMaxByteCount(inputString.Length)
' Counteract the compiler adding an extra element.
Dim encodedBytes(numberOfEncodedBytes - 1) As Byte
' --------------------------------------------------------------------------
Console.Clear()
' Display the name of the encoding.
Console.WriteLine("The name of the encoding is ""{0}""." & vbCrLf, ae.WebName)
' Display the input string in text.
Console.WriteLine("Input string ({0} characters): ""{1}""", _
inputString.Length, inputString)
' Display the input string in hexadecimal.
' Each element is converted to an integer with Convert.ToInt32.
Console.Write("Input string in hexadecimal: ")
Dim c As Char
For Each c In inputString.ToCharArray()
Console.Write("0x{0:X2} ", Convert.ToInt32(c))
Next c
Console.Write(twoNewLines)
' --------------------------------------------------------------------------
' Attempt to encode the input string. However, an exception is thrown before
' the input string can be encoded.
Console.WriteLine("Encode the input string...")
' The code example terminates during the call to the GetBytes() method.
Try
numberOfEncodedBytes = ae.GetBytes(inputString, 0, inputString.Length, _
encodedBytes, 0)
Catch e As EncoderFallbackException
Console.WriteLine(e)
Console.WriteLine(vbCrLf & _
"*** THE CODE EXAMPLE TERMINATES HERE AS INTENDED. ***")
Return
End Try
' This statement is never executed.
Console.WriteLine("This statement is never executed.")
End Sub 'Main
End Class 'Sample
'
'This code example produces the following results:
'
'The name of the encoding is "us-ascii".
'
'Input string (3 characters): "X"
'Input string in hexadecimal: 0xAB 0x58 0xBB
'
'Encode the input string...
'System.Text.EncoderFallbackException: Unable to translate Unicode character \u00AB at inde
'x 0 to specified code page.
' at System.Text.EncoderExceptionFallbackBuffer.Fallback(Char charUnknown, Int32 index)
' at System.Text.EncoderFallbackBuffer.InternalFallback(Char ch, Char*& chars)
' at System.Text.ASCIIEncoding.GetBytes(Char* chars, Int32 charCount, Byte* bytes, Int32
'byteCount, EncoderNLS encoder)
' at System.Text.ASCIIEncoding.GetBytes(String chars, Int32 charIndex, Int32 charCount, B
'yte[] bytes, Int32 byteIndex)
' at Sample.Main()
'
'*** THE CODE EXAMPLE TERMINATES HERE AS INTENDED. ***
'
Constructors
| EncoderFallbackException() |
Initializes a new instance of the EncoderFallbackException class. |
| EncoderFallbackException(String) |
Initializes a new instance of the EncoderFallbackException class. A parameter specifies the error message. |
| EncoderFallbackException(String, Exception) |
Initializes a new instance of the EncoderFallbackException class. Parameters specify the error message and the inner exception that is the cause of this exception. |
Properties
| CharUnknown |
Gets the input character that caused the exception. |
| CharUnknownHigh |
Gets the high component character of the surrogate pair that caused the exception. |
| CharUnknownLow |
Gets the low component character of the surrogate pair that caused the exception. |
| Index |
Gets the index position in the input buffer of the character that caused the exception. |
Methods
| IsUnknownSurrogate() |
Indicates whether the input that caused the exception is a surrogate pair. |