Today, I had some free time to come back to our on-going Flutter projects. One of my tasks was “reverse a string”, easy enough, right? Without thinking I typed the code confidently, but I was very surprised, Dart does not support any method to reverse a string. Haha, are you kidding me, Dart?

I still didn’t believe that, I did some searches on the internet and I ended-up to find some ways to just “reverse a string in Dart”. I am happy to share them here:

Use split and join:

String reverseStringUsingSplit(String input) {
  var chars = input.split('');
  return chars.reversed.join();
}

Use runes:

String reverseStringUsingRunes(String input) {
  var chars = input.runes.toList();

  return String.fromCharCodes(chars.reversed);
}

Use codeUnits:

String reverseStringUsingCodeUnits(String input) {
  return String.fromCharCodes(input.codeUnits.reversed);
}

I don’t really understand why Dart ignore this basic method. But it is interesting to implement reverse method ourself, isn’t it? Let’s put all the code together:

void main() {
  var coflutter = 'Coflutter';

  print(reverseStringUsingSplit(coflutter));
  print(reverseStringUsingRunes(coflutter));
  print(reverseStringUsingCodeUnits(coflutter));
}

String reverseStringUsingSplit(String input) {
  var chars = input.split('');
  return chars.reversed.join();
}

String reverseStringUsingRunes(String input) {
  var chars = input.runes.toList();

  return String.fromCharCodes(chars.reversed);
}

String reverseStringUsingCodeUnits(String input) {
  return String.fromCharCodes(input.codeUnits.reversed);
}

// Output
rettulfoC
rettulfoC
rettulfoC

Phuc Tran

Creator of Coflutter.
Daddy at home.
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