如何：在舊式編碼與 Unicode 之間轉換（C# 編程指南） · MSDN C# 編程指南 & 參考手冊 2015

# 如何：在舊式編碼與 Unicode 之間轉換（C# 編程指南）在 C# 中，內存中的所有字符串都是按 Unicode (UTF-16) 編碼的。將數據從存儲器移動到 **string** 對象中后，數據將自動轉換為 UTF-16。如果數據僅包含從 0 到 127 的 ASCII 值，則此轉換無需您執行任何額外的工作。但若源文本包含擴展的 ASCII 字節值（128 到 255），則默認情況下，將根據當前代碼頁解釋擴展字符。若要指定應該根據其他某個代碼頁解釋源文本，請使用 [System.Text.Encoding](https://msdn.microsoft.com/zh-cn/library/system.text.encoding.aspx) 類，如下面的示例所示。下面的示例演示如何轉換按 8 位 ASCII 編碼的文本文件，此轉換根據 Windows 代碼頁 737 解釋源文本。 ``` class ANSIToUnicode { static void Main() { // Create a file that contains the Greek work ψυχ? (psyche) when interpreted by using // code page 737 ((DOS) Greek). You can also create the file by using Character Map // to paste the characters into Microsoft Word and then "Save As" by using the DOS // (Greek) encoding. (Word will actually create a six-byte file by appending "\r\n" at the end.) System.IO.File.WriteAllBytes(@"greek.txt", new byte[] { 0xAF, 0xAC, 0xAE, 0x9E }); // Specify the code page to correctly interpret byte values Encoding encoding = Encoding.GetEncoding(737); //(DOS) Greek code page byte[] codePageValues = System.IO.File.ReadAllBytes(@"greek.txt"); // Same content is now encoded as UTF-16 string unicodeValues = encoding.GetString(codePageValues); // Show that the text content is still intact in Unicode string // (Add a reference to System.Windows.Forms.dll) System.Windows.Forms.MessageBox.Show(unicodeValues); // Same content "ψυχ?" is stored as UTF-8 System.IO.File.WriteAllText(@"greek_unicode.txt", unicodeValues); // Conversion is complete. Show the bytes to prove the conversion. Console.WriteLine("8-bit encoding byte values:"); foreach(byte b in codePageValues) Console.Write("{0:X}-", b); Console.WriteLine(); Console.WriteLine("Unicode values:"); string unicodeString = System.IO.File.ReadAllText("greek_unicode.txt"); System.Globalization.TextElementEnumerator enumerator = System.Globalization.StringInfo.GetTextElementEnumerator(unicodeString); while(enumerator.MoveNext()) { string s = enumerator.GetTextElement(); int i = Char.ConvertToUtf32(s, 0); Console.Write("{0:X}-", i); } Console.WriteLine(); // Keep the console window open in debug mode. Console.Write("Press any key to exit."); Console.ReadKey(); } /* * Output: 8-bit encoding byte values: AF-AC-AE-9E Unicode values: 3C8-3C5-3C7-3B7 */ } ``` ## 請參閱 [字符串（C# 編程指南）](https://msdn.microsoft.com/zh-cn/library/ms228362.aspx)