Question

The intention of the code is printing unicode as japanese characters to a file

   String s = "\u30a2\u30c3\u30d7\u30ed\u30fc\u30c9\u3059\u308b\u30d5\u30a1\u30a4\u30eb\u304c\u6307\u5b9a\u3055\u308c\u3066\u3044\u307e\u305b\u3093";
   var Bytes = Encoding.Unicode.GetBytes(s);      
   string  key = Encoding.UTF8.GetString(Encoding.Convert(Encoding.Unicode, Encoding.UTF8, Bytes));

Key is I want to print to file but has the value \u30a2\u30c3\u30d7\u30ed\u30fc\u30c9\u3059\u308b\u30d5\u30a1\u30a4\u30eb\u304c\u6307\u5b9a\u3055\u308c\u3066\u3044\u307e\u305b\u3093 Any ideas whats wrong?

Answer 1

What’s wrong is that a string (key) has no notion of the bytes used to store it. In this case, your string is:

String:

アップロードするファイルが指定されていません

this is exactly what

"\u30a2\u30c3\u30d7\u30ed\u30fc\u30c9\u3059\u308b\u30d5\u30a1\u30a4\u30eb\u304c\u6307\u5b9a\u3055\u308c\u3066\u3044\u307e\u305b\u3093" 

means. The expression '\u30a3' looks like 2 Unicode bytes, but it actually just means the character 'ア'.

if you save to a UTF-8 file, the bytes written will be:

UTF-8 bytes

File.WriteAllText("temp.txt", "アップロードするファイルが指定されていません", Encoding.UTF8);

The contents will be (in bytes)

 E3 82 A2 E3 83 83 E3 83 97 E3 83 AD E3 83 BC E3 83 89 E3 81 99 E3 82 8B E3 83 
 95 E3 82 A1 E3 82 A4 E3 83 AB E3 81 8C E6 8C 87 E5 AE 9A E3 81 95 E3 82 8C E3 
 81 A6 E3 81 84 E3 81 BE E3 81 9B E3 82 93

UTF-16 bytes

File.WriteAllText("temp.txt", "アップロードするファイルが指定されていません", Encoding.Unicode);

The contents will be (in bytes)

 A2 30 C3 30 D7 30 ED 30 FC 30 C9 30 59 30 8B 30 D5 30 A1 30 A4 30 EB 30 4C 30 
 07 63 9A 5B 55 30 8C 30 66 30 44 30 7E 30 5B 30 93 30