DecoderFallbackException Class
The exception that is thrown when a decoder fallback operation fails. This class cannot be inherited.
System.Exception
System.SystemException
System.ArgumentException
System.Text.DecoderFallbackException
Assembly: mscorlib (in mscorlib.dll)
The DecoderFallbackException type exposes the following members.
| Name | Description | |
|---|---|---|
![]() ![]() | DecoderFallbackException | Initializes a new instance of the DecoderFallbackException class. |
![]() ![]() | DecoderFallbackException(String) | Initializes a new instance of the DecoderFallbackException class. A parameter specifies the error message. |
![]() ![]() | DecoderFallbackException(String, Exception) | Initializes a new instance of the DecoderFallbackException class. Parameters specify the error message and the inner exception that is the cause of this exception. |
![]() ![]() | DecoderFallbackException(String, Byte(), Int32) | Initializes a new instance of the DecoderFallbackException class. Parameters specify the error message, the array of bytes being decoded, and the index of the byte that cannot be decoded. |
| Name | Description | |
|---|---|---|
![]() ![]() | BytesUnknown | Gets the input byte sequence that caused the exception. |
![]() | Data | Gets a collection of key/value pairs that provide additional user-defined information about the exception. (Inherited from Exception.) |
![]() | HelpLink | Gets or sets a link to the help file associated with this exception. (Inherited from Exception.) |
![]() ![]() | HResult | Gets or sets HRESULT, a coded numerical value that is assigned to a specific exception. (Inherited from Exception.) |
![]() ![]() | Index | Gets the index position in the input byte sequence of the byte that caused the exception. |
![]() ![]() | InnerException | Gets the Exception instance that caused the current exception. (Inherited from Exception.) |
![]() | Message | Gets the error message and the parameter name, or only the error message if no parameter name is set. (Inherited from ArgumentException.) |
![]() | ParamName | Gets the name of the parameter that causes this exception. (Inherited from ArgumentException.) |
![]() | Source | Gets or sets the name of the application or the object that causes the error. (Inherited from Exception.) |
![]() ![]() | StackTrace | Gets a string representation of the immediate frames on the call stack. (Inherited from Exception.) |
![]() | TargetSite | Gets the method that throws the current exception. (Inherited from Exception.) |
| Name | Description | |
|---|---|---|
![]() ![]() | Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
![]() ![]() | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
![]() ![]() | GetBaseException | When overridden in a derived class, returns the Exception that is the root cause of one or more subsequent exceptions. (Inherited from Exception.) |
![]() ![]() | GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
![]() | GetObjectData | Sets the SerializationInfo object with the parameter name and additional exception information. (Inherited from ArgumentException.) |
![]() | GetType | Gets the runtime type of the current instance. (Inherited from Exception.) |
![]() ![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() ![]() | ToString | Creates and returns a string representation of the current exception. (Inherited from Exception.) |
| Name | Description | |
|---|---|---|
![]() | SerializeObjectState | Occurs when an exception is serialized to create an exception state object that contains serialized data about the exception. (Inherited from Exception.) |
The following code example demonstrates the DecoderExceptionFallback and DecoderFallbackException classes.
' This example demonstrates the DecoderExceptionFallback 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 DecoderExceptionFallback parameter specifies that an exception ' is thrown if a character cannot be encoded. ' An encoder exception fallback is also specified, but in this code ' example the encoding operation cannot fail. Dim eef As New EncoderExceptionFallback() Dim def As New DecoderExceptionFallback() Dim ae As Encoding = Encoding.GetEncoding("us-ascii", eef, def) Dim inputString As String = "XYZ" Dim decodedString As String Dim twoNewLines As String = vbCrLf & vbCrLf Dim numberOfEncodedBytes As Integer = ae.GetByteCount(inputString) ' 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) ' -------------------------------------------------------------------------- ' Encode the input string. Console.WriteLine("Encode the input string...") numberOfEncodedBytes = ae.GetBytes(inputString, 0, inputString.Length, _ encodedBytes, 0) ' Display the encoded bytes. ' Each element is converted to an integer with Convert.ToInt32. Console.WriteLine("Encoded bytes in hexadecimal ({0} bytes):" & vbCrLf, _ numberOfEncodedBytes) Dim b As Byte For Each b In encodedBytes Console.Write("0x{0:X2} ", Convert.ToInt32(b)) Next b Console.Write(twoNewLines) ' -------------------------------------------------------------------------- ' Replace the encoded byte sequences for the characters 'X' and 'Z' with the ' value 0xFF, which is outside the valid range of 0x00 to 0x7F for ' ASCIIEncoding. The resulting byte sequence is actually the beginning of ' this code example because it is the input to the decoder operation, and ' is equivalent to a corrupted or improperly encoded byte sequence. encodedBytes(0) = &HFF encodedBytes(2) = &HFF Console.WriteLine("Display the corrupted byte sequence...") ' Each element is converted to an integer with Convert.ToInt32. Console.WriteLine("Encoded bytes in hexadecimal ({0} bytes):" & vbCrLf, _ numberOfEncodedBytes) For Each b In encodedBytes Console.Write("0x{0:X2} ", Convert.ToInt32(b)) Next b Console.Write(twoNewLines) ' -------------------------------------------------------------------------- ' Attempt to decode the encoded bytes. However, an exception is thrown ' before the byte sequence can be decoded. Console.WriteLine("Compare the decoded bytes to the input string...") Try decodedString = ae.GetString(encodedBytes) Catch dfe As DecoderFallbackException Console.WriteLine(dfe) 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): "XYZ" 'Input string in hexadecimal: 0x58 0x59 0x5A ' 'Encode the input string... 'Encoded bytes in hexadecimal (3 bytes): ' '0x58 0x59 0x5A ' 'Display the corrupted byte sequence... 'Encoded bytes in hexadecimal (3 bytes): ' '0xFF 0x59 0xFF ' 'Compare the decoded bytes to the input string... 'System.Text.DecoderFallbackException: Unable to translate bytes [FF] at index 0 from speci 'fied code page to Unicode. ' at System.Text.DecoderExceptionFallbackBuffer.Throw(Byte[] bytesUnknown, Int32 index) ' at System.Text.DecoderExceptionFallbackBuffer.Fallback(Byte[] bytesUnknown, Int32 index ') ' at System.Text.DecoderFallbackBuffer.InternalFallback(Byte[] bytes, Byte* pBytes) ' at System.Text.ASCIIEncoding.GetCharCount(Byte* bytes, Int32 count, DecoderNLS decoder) ' ' at System.String.CreateStringFromEncoding(Byte* bytes, Int32 byteLength, Encoding encod 'ing) ' at System.Text.ASCIIEncoding.GetString(Byte[] bytes, Int32 byteIndex, Int32 byteCount) ' at System.Text.Encoding.GetString(Byte[] bytes) ' at Sample.Main() ' '*** THE CODE EXAMPLE TERMINATES HERE AS INTENDED. *** ' '
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.





