Async and Practical

FizzBuzz Rule Order

FizzBuzz is the classic test of else if ordering: % 15 has to be checked first, otherwise 15 would match % 3 and get labeled Fizz. The loop appends one label per value and a final join builds the deterministic summary.

Program

Play the program to label four numbers with FizzBuzz rules.

fizzbuzz.dart
Replay: real traced execution (multi-file project)
void main() {
  var values = [15, 3, 5, 16];
  var labels = <String>[];
  for (var n in values) {
    if (n % 15 == 0) {
      labels.add('FizzBuzz');
    } else if (n % 3 == 0) {
      labels.add('Fizz');
    } else if (n % 5 == 0) {
      labels.add('Buzz');
    } else {
      labels.add('$n');
    }
  }
  print(labels.join(','));
}

  1. values ← [15, 3, 5, 16]

    1void main() {2  var values = [15, 3, 5, 16];3  var labels = <String>[];
    values this step[15, 3, 5, 16]values

  2. labels ← []

    2var values = [15, 3, 5, 16];3var labels = <String>[];4for (var n in values) {
    values this step[]labels

  3. rules ← %15, %3, %5, else

    3var labels = <String>[];4for (var n in values) {5  if (n % 15 == 0) {
    values this step%15, %3, %5, elserules[15, 3, 5, 16]values

  4. label ← FizzBuzz

    5if (n % 15 == 0) {6  labels.add('FizzBuzz');7} else if (n % 3 == 0) {
    values this stepFizzBuzzlabel15n

  5. label ← Fizz

    7} else if (n % 3 == 0) {8  labels.add('Fizz');9} else if (n % 5 == 0) {
    values this stepFizzlabel3n

  6. label ← Buzz

    9} else if (n % 5 == 0) {10  labels.add('Buzz');11} else {
    values this stepBuzzlabel5n

  7. label ← 16

    11} else {12  labels.add('$n');13}
    values this step16label16n

  8. labels ← [FizzBuzz, Fizz, Buzz, 16]

    13  }14}15print(labels.join(','));
    values this step[FizzBuzz, Fizz, Buzz, 16]labels

  9. print(labels.join(','));

    14  }15  print(labels.join(','));16}
    outputFizzBuzz,Fizz,Buzz,16
    values this step[FizzBuzz, Fizz, Buzz, 16]labels
rule order `% 15` is checked first; otherwise `15` would match `% 3` and stop as `Fizz`.
else if chain Only one arm runs per iteration; once a match wins, the rest are skipped.
collect then join Appending to `labels` and joining once at the end keeps the final string deterministic.