How can I make conversion between bytes and Unicode in Dart?

Question

I try to implement Irn answer in How to work with char types in Dart? (Print alphabet) But didn't catch exactly how to do it.

Example In my Dart code İ capital i with dot above represent as byte[304] and I have to replace this with server byte[152] and send to server as byte not a string.

Test-1:

cpToLatin9(int cp) => const {0x11e: 0xd0, 0x11f: 0xf0, 0x130: 0xdd, 0x131: 0xfd, 0x15e: 0xde, 0x15f: 0xfe}[cp] ?? cp;
latin9ToCp(int latin9Char) => const {0xd0: 0x11e, 0xf0: 0x11f, 0xdd: 0x130, 0xfd: 0x131, 0xde: 0x15e, 0xfe: 0x15f}[latin9Char] ?? latin9Char;


String iso08859_9 = "çÇğĞıİşŞöÖüÜ";
List<int> bytes = utf8.encode(iso08859_9);

 for (var i = 0; i < bytes.length; i++) {
    int byte = bytes[i];
    var latin9ToCodePoint = latin9ToCp(byte);
    print("latin9ToCodePoint: $latin9ToCodePoint");

    var latin9ToCodePointChar = String.fromCharCode(latin9ToCodePoint);
    print("latin9ToCodePointChar: $latin9ToCodePointChar");
  }

Output:

iso08859_9 bytes: [195, 167, 195, 135, 196, 159, 196, 158, 196, 177, 196, 176, 197, 159, 197, 158, 195, 182, 195, 150, 195, 188, 195, 156]
latin9ToCodePoint: 195
latin9ToCodePointChar: Ã
latin9ToCodePoint: 167
latin9ToCodePointChar: §
latin9ToCodePoint: 195
latin9ToCodePointChar: Ã
latin9ToCodePoint: 135
latin9ToCodePointChar: 
latin9ToCodePoint: 196
latin9ToCodePointChar: Ä
latin9ToCodePoint: 159
latin9ToCodePointChar: 
latin9ToCodePoint: 196
latin9ToCodePointChar: Ä
latin9ToCodePoint: 158
latin9ToCodePointChar: 
latin9ToCodePoint: 196
latin9ToCodePointChar: Ä
latin9ToCodePoint: 177
latin9ToCodePointChar: ±
latin9ToCodePoint: 196
latin9ToCodePointChar: Ä
latin9ToCodePoint: 176
latin9ToCodePointChar: °
latin9ToCodePoint: 197
latin9ToCodePointChar: Å
latin9ToCodePoint: 159
latin9ToCodePointChar: 
latin9ToCodePoint: 197
latin9ToCodePointChar: Å
latin9ToCodePoint: 158
latin9ToCodePointChar: 
latin9ToCodePoint: 195
latin9ToCodePointChar: Ã
latin9ToCodePoint: 182
latin9ToCodePointChar: ¶
latin9ToCodePoint: 195
latin9ToCodePointChar: Ã
latin9ToCodePoint: 150
latin9ToCodePointChar: 
latin9ToCodePoint: 195
latin9ToCodePointChar: Ã
latin9ToCodePoint: 188
latin9ToCodePointChar: ¼
latin9ToCodePoint: 195
latin9ToCodePointChar: Ã
latin9ToCodePoint: 156
latin9ToCodePointChar:

Test-2: If I change List bytes = utf8.encode(iso08859_9); to

List bytes = iso08859_9.codeUnits; I get a different result.

In my Dart I test it that the iso08859_9 character represent as iso08859_9 bytes:

[231, 199, 287, 286, 305, 304, 351, 350, 246, 214, 252, 220]

Now my main problem to change the bytes to IBM CP bytes to

[135, 128, 167, 166, 141, 152, 159, 158, 148, 153, 129, 154]

When I do this and use socket.add(ibmcp_bytes) to server the character is nor readable.

Update:

try this and find out 1 and 2 bytes as a result. ???

print("ç".runes.length);
print(utf8.encode("ç").length);

Seth Kitchen · Answer 1 · 2020-08-06T17:44:43.923

Just found it today -

// Random Unicode Byte Array
var someArray = [50, 198, 167, 52, 198, 167, 54, 198, 167, 67, 111, 108, 111, 114, 40, 48, 120, 102, 102, 100, 99, 100, 100, 101, 50, 41, 207, 159, 48, 207, 159, 48, 207, 159, 49, 207, 159, 104, 116, 116, 112, 115, 58, 47, 47, 99, 111, 109, 112, 97, 116, 105, 111, 46, 103, 105, 116, 104, 117, 98, 46, 105, 111, 47, 116, 114, 97, 110, 115, 112, 97, 114, 101, 110, 116, 70, 105, 108, 108, 101, 114, 46, 112, 110, 103, 207, 159, 73, 109, 97, 103, 101, 82, 101, 112, 101, 97, 116, 46, 110, 111, 82, 101, 112, 101, 97, 116, 207, 159, 66, 111, 120, 70, 105, 116, 46, 99, 111, 118, 101, 114, 207, 159, 50, 48, 207, 159, 98, 111, 116, 116, 111, 109, 76, 101, 102, 116, 198, 167, 72, 111, 109, 101, 80, 97, 103, 101, 67, 111, 109, 112, 111, 110, 101, 110, 116, 84, 121, 112, 101, 115, 46, 66, 97, 110, 110, 101, 114, 49, 198, 171, 54, 198, 171, 50, 198, 171, 79, 112, 101, 110, 32, 82, 111, 97, 100, 115, 207, 159, 83, 105, 122, 105, 110, 103, 46, 72, 101, 97, 100, 76, 105, 110, 101, 50, 207, 159, 67, 111, 108, 111, 114, 40, 48, 120, 102, 102, 102, 102, 102, 102, 102, 102, 41, 207, 159, 84, 101, 120, 116, 65, 108, 105, 103, 110, 46, 114, 105, 103, 104, 116, 198, 132, 207, 159, 83, 105, 122, 105, 110, 103, 46, 83, 117, 98, 116, 105, 116, 108, 101, 50, 207, 159, 67, 111, 108, 111, 114, 40, 48, 120, 102, 102, 102, 102, 102, 102, 102, 102, 41, 207, 159, 84, 101, 120, 116, 65, 108, 105, 103, 110, 46, 99, 101, 110, 116, 101, 114, 198, 132, 83, 104, 111, 112, 32, 67, 111, 108, 108, 101, 99, 116, 105, 111, 110, 207, 159, 83, 105, 122, 105, 110, 103, 46, 66, 117, 116, 116, 111, 110, 207, 159, 67, 111, 108, 111, 114, 40, 48, 120, 102, 102, 48, 48, 48, 48, 48, 48, 41, 207, 159, 99, 101, 110, 116, 101, 114, 207, 159, 67, 111, 108, 111, 114, 40, 48, 120, 102, 102, 101, 99, 97, 101, 49, 57, 41, 207, 159, 104, 116, 116, 112, 58, 47, 47, 115, 117, 110, 115, 104, 105, 110, 101, 98, 105, 107, 101, 46, 99, 111, 109, 47, 207, 159, 49, 50, 53, 207, 159, 51, 48, 207, 159, 67, 111, 108, 111, 114, 40, 48, 120, 48, 48, 48, 48, 48, 48, 48, 48, 41, 198, 132, 67, 111, 108, 111, 114, 40, 48, 120, 102, 102, 48, 48, 48, 48, 48, 48, 41, 207, 159, 48, 207, 159, 48, 207, 159, 48, 46, 50, 57, 48, 52, 55, 54, 49, 57, 48, 52, 55, 54, 49, 56, 57, 54, 55, 207, 159, 104, 116, 116, 112, 115, 58, 47, 47, 99, 111, 109, 112, 97, 116, 105, 111, 46, 103, 105, 116, 104, 117, 98, 46, 105, 111, 47, 111, 112, 101, 110, 45, 114, 111, 97, 100, 46, 106, 112, 103, 207, 159, 73, 109, 97, 103, 101, 82, 101, 112, 101, 97, 116, 46, 110, 111, 82, 101, 112, 101, 97, 116, 207, 159, 66, 111, 120, 70, 105, 116, 46, 99, 111, 118, 101, 114, 207, 159, 48, 207, 159, 99, 101, 110, 116, 101, 114]; 

// Initialize object which decodes unicode -- cannot decode statically
Utf8Decoder decode=new Utf8Decoder(); 

// Convert a list of Unicode bytes to String
// Decodes to something like 2Ƨ4Ƨ6ƧColor(0xffdcdde2)ϟ0ϟ0ϟ1ϟ...
String content = decode.convert(someArray);

How can I make conversion between bytes and Unicode in Dart?

1 Answers1