DecoderReplacementFallback クラス
アセンブリ: mscorlib (mscorlib.dll 内)

<SerializableAttribute> _ Public NotInheritable Class DecoderReplacementFallback Inherits DecoderFallback

エンコード操作やデコード操作が失敗する一般的な理由は、基底のエンコーディング クラスで、文字とそれに対応するバイト シーケンスをマップできないことです。入力バイト シーケンスを出力文字に変換できない場合、DecoderReplacementFallback オブジェクトは、元の入力バイト シーケンスを表現するために、置換文字列を作成して出力に挿入します。その後、変換プロセスは、元の入力の残りを引き続きデコードします。
DecoderReplacementFallback オブジェクトの値は、このオブジェクトの初期化に使用された置換文字列です。

DecoderReplacementFallback クラスのコード例を次に示します。
' This example demonstrates the DecoderReplacementFallback 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 DecoderReplacementFallback parameter specifies that the ' string "(error)" is to replace characters that cannot be decoded. ' An encoder replacement fallback is also specified, but in this code ' example the encoding operation cannot fail. Dim erf As New EncoderReplacementFallback("(unknown)") Dim drf As New DecoderReplacementFallback("(error)") Dim ae As Encoding = Encoding.GetEncoding("us-ascii", erf, drf) 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 implicitly 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...") 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) ' -------------------------------------------------------------------------- ' Decode the encoded bytes. Console.WriteLine("Compare the decoded bytes to the input string...") decodedString = ae.GetString(encodedBytes) ' Display the input string and the decoded string for comparison. Console.WriteLine("Input string: ""{0}""", inputString) Console.WriteLine("Decoded string:""{0}""", decodedString) 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... 'Input string: "XYZ" 'Decoded string:"(error)Y(error)" '
// This example demonstrates the DecoderReplacementFallback 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 DecoderReplacementFallback parameter specifies that the // string "(error)" is to replace characters that cannot be decoded. // An encoder replacement fallback is also specified, but in this code // example the encoding operation cannot fail. Encoding ae = Encoding.GetEncoding( "us-ascii", new EncoderReplacementFallback("(unknown)"), new DecoderReplacementFallback("(error)")); string inputString = "XYZ"; string decodedString; string twoNewLines = "\n\n"; byte[] encodedBytes = new byte[ae.GetByteCount(inputString)]; 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); // -------------------------------------------------------------------------- // Encode the input string. Console.WriteLine("Encode the input string..."); numberOfEncodedBytes = ae.GetBytes(inputString, 0, inputString.Length, encodedBytes, 0); // Display the encoded bytes. Console.WriteLine("Encoded bytes in hexadecimal ({0} bytes):\n", numberOfEncodedBytes); foreach (byte b in encodedBytes) { Console.Write("0x{0:X2} ", (int)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] = 0xFF; encodedBytes[2] = 0xFF; Console.WriteLine("Display the corrupted byte sequence..."); Console.WriteLine("Encoded bytes in hexadecimal ({0} bytes):\n", numberOfEncodedBytes); foreach (byte b in encodedBytes) { Console.Write("0x{0:X2} ", (int)b); } Console.Write(twoNewLines); // -------------------------------------------------------------------------- // Decode the encoded bytes. Console.WriteLine("Compare the decoded bytes to the input string..."); decodedString = ae.GetString(encodedBytes); // Display the input string and the decoded string for comparison. Console.WriteLine("Input string: \"{0}\"", inputString); Console.WriteLine("Decoded string:\"{0}\"", decodedString); } } /* 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... Input string: "XYZ" Decoded string:"(error)Y(error)" */
// This example demonstrates the DecoderReplacementFallback class. using namespace System; using namespace System::Text; int main() { // Create an encoding, which is equivalent to calling the // ASCIIEncoding class constructor. // The DecoderReplacementFallback parameter specifies that the // string "(error)" is to replace characters that cannot be decoded. // An encoder replacement fallback is also specified, but in this code // example the encoding operation cannot fail. Encoding^ asciiEncoding = Encoding::GetEncoding("us-ascii", gcnew EncoderReplacementFallback("(unknown)"), gcnew DecoderReplacementFallback("(error)")); String^ inputString = "XYZ"; String^ decodedString; String^ twoNewLines = Environment::NewLine + Environment::NewLine; array<Byte>^ encodedBytes = gcnew array<Byte>( asciiEncoding->GetByteCount(inputString)); 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); // --------------------------------------------------------------------- // Encode the input string. Console::WriteLine("Encode the input string..."); numberOfEncodedBytes = asciiEncoding->GetBytes(inputString, 0, inputString->Length, encodedBytes, 0); // Display the encoded bytes. Console::WriteLine("Encoded bytes in hexadecimal ({0} bytes):{1}", numberOfEncodedBytes, Environment::NewLine); for each (Byte b in encodedBytes) { Console::Write("0x{0:X2} ", 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] = 0xFF; encodedBytes[2] = 0xFF; Console::WriteLine("Display the corrupted byte sequence..."); Console::WriteLine("Encoded bytes in hexadecimal ({0} bytes):{1}", numberOfEncodedBytes, Environment::NewLine); for each (Byte b in encodedBytes) { Console::Write("0x{0:X2} ", b); } Console::Write(twoNewLines); // --------------------------------------------------------------------- // Decode the encoded bytes. Console::WriteLine("Compare the decoded bytes to the input string..."); decodedString = asciiEncoding->GetString(encodedBytes); // Display the input string and the decoded string for comparison. Console::WriteLine("Input string: \"{0}\"", inputString); Console::WriteLine("Decoded string:\"{0}\"", decodedString); } /* 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... Input string: "XYZ" Decoded string:"(error)Y(error)" */

System.Text.DecoderFallback
System.Text.DecoderReplacementFallback


Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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DecoderReplacementFallback メンバ
System.Text 名前空間
DecoderReplacementFallbackBuffer
DecoderReplacementFallback
DefaultString
- DecoderReplacementFallback クラスのページへのリンク