%u0BB5%u0BA3%u0B95%u0BCD%u0B95%u0BAE%u0BCD

Above is unicode with hex characters string Need to convert that to readable text When decoded, the above text will return வணக்கம் meaning welcome

CodePudding user response：

If you want a hard-coded string, as noted in Special characters in Flutter and in the Dart Language Tour, you can use \u to specify Unicode code points:

var welcome = '\u0BB5\u0BA3\u0B95\u0BCD\u0B95\u0BAE\u0BCD';

If you are given a string '%u0BB5%u0BA3%u0B95%u0BCD%u0B95%u0BAE%u0BCD' and need to convert it dynamically at runtime, then you will need to:

1. Split the string into %uXXXX components.
2. Parse the XXXX portion as a hexadecimal integer to get the code point.
3. Construct a String from the code points.

void main() {
  var s = '%u0BB5%u0BA3%u0B95%u0BCD%u0B95%u0BAE%u0BCD';
  var re = RegExp(r'%u(?<codePoint>[0-9A-Fa-f]{4})');
  var matches = re.allMatches(s);
  var codePoints = [
    for (var match in matches)
      int.parse(match.namedGroup('codePoint')!, radix: 16),
  ];
  var decoded = String.fromCharCodes(codePoints);
  print(decoded); // Prints: வணக்கம்
}

Edit: An adjusted version that can handle strings with a mixture of encoded code points and unencoded characters:

void main() {
  var s = '%u0BB5%u0BA3%u0B95%u0BCD%u0B95%u0BAE%u0BCD'
      ' hello world! '
      '%u0BB5%u0BA3%u0B95%u0BCD%u0B95%u0BAE%u0BCD';
  var re = RegExp(r'(%u(?<codePoint>[0-9A-Fa-f]{4}))|.');
  var matches = re.allMatches(s);
  var codePoints = <int>[];
  for (var match in matches) {
    var codePoint = match.namedGroup('codePoint');
    if (codePoint != null) {
      codePoints.add(int.parse(codePoint, radix: 16));
    } else {
      codePoints  = match.group(0)!.runes.toList();
    }
  }
  var decoded = String.fromCharCodes(codePoints);
  print(decoded); // Prints: வணக்கம் hello world! வணக்கம்
}