如何：在旧式编码与 Unicode 之间转换（C# 编程指南） · MSDN C# 编程指南 & 参考手册 2015

# 如何：在旧式编码与 Unicode 之间转换（C# 编程指南）在 C# 中，内存中的所有字符串都是按 Unicode (UTF-16) 编码的。将数据从存储器移动到 **string** 对象中后，数据将自动转换为 UTF-16。如果数据仅包含从 0 到 127 的 ASCII 值，则此转换无需您执行任何额外的工作。但若源文本包含扩展的 ASCII 字节值（128 到 255），则默认情况下，将根据当前代码页解释扩展字符。若要指定应该根据其他某个代码页解释源文本，请使用 [System.Text.Encoding](https://msdn.microsoft.com/zh-cn/library/system.text.encoding.aspx) 类，如下面的示例所示。下面的示例演示如何转换按 8 位 ASCII 编码的文本文件，此转换根据 Windows 代码页 737 解释源文本。 ``` class ANSIToUnicode { static void Main() { // Create a file that contains the Greek work ψυχή (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 "ψυχή" 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 */ } ``` ## 请参阅 [字符串（C# 编程指南）](https://msdn.microsoft.com/zh-cn/library/ms228362.aspx)