dart conversion from different size

readme.md

dart conversion from different size

Created with <3 with dartpad.dev.

main.dart

void main() {
  smallest_int();
  print('----------------');
  smaller_int();
  print('----------------');
  is_it_a_bug_or_a_feature();
}

void smallest_int() {
  print('equivalent in Rust: 1970-01-01 00:02:30.151152 UTC (ms 150151152)');
  final ms = 150151152;
  print('ms: $ms');
  final date = DateTime.fromMicrosecondsSinceEpoch(ms, isUtc: true);
  print('date: $date');

  print('ms since epoch: ${date.microsecondsSinceEpoch}');
}

void smaller_int() {
  print('equivalent in Rust: 1970-01-02 17:42:31.152153 UTC (ms 150151152153)');
  final ms = 150151152153;
  print('ms: $ms');
  final date = DateTime.fromMicrosecondsSinceEpoch(ms, isUtc: true);
  print('date: $date');

  print('ms since epoch: ${date.microsecondsSinceEpoch}');
}

void is_it_a_bug_or_a_feature() {
  print(
      'equivalent in Rust: 1974-10-04 20:39:12.153154 UTC (ms 150151152153154)');
  final ms = 150151152153154;
  final modified = 150151152153154 * 1000;
  print('ms: $ms');
  print('ms multiplied by 1000: $modified');
  final date = DateTime.fromMicrosecondsSinceEpoch(ms, isUtc: true);
  final date_modified =
      DateTime.fromMicrosecondsSinceEpoch(modified, isUtc: true);
  print('date: $date');
  print('date with multiplied ms: $date_modified');

  print('ms since epoch: ${date.microsecondsSinceEpoch}');
  print(
      'ms since epoch date with multiplied ms: ${date_modified.microsecondsSinceEpoch}');
}

console output:

equivalent in Rust: 1970-01-01 00:02:30.151152 UTC (ms 150151152)
ms: 150151152
date: 1970-01-01 00:02:30.151Z
ms since epoch: 150151000
----------------
equivalent in Rust: 1970-01-02 17:42:31.152153 UTC (ms 150151152153)
ms: 150151152153
date: 1970-01-02 17:42:31.152Z
ms since epoch: 150151152000
----------------
equivalent in Rust: 1974-10-04 20:39:12.153154 UTC (ms 150151152153154)
ms: 150151152153154
ms multiplied by 1000: 150151152153154000
date: 1974-10-04 20:39:12.153Z
date with multiplied ms: 6728-02-07 13:22:33.154Z
ms since epoch: 150151152153000
ms since epoch date with multiplied ms: 150151152153154000

There definitely seems to be a bug because:

• without multiplying by 1000, one gets a correct DateTime
• without multiplying by 1000, one cannot retrieve the original last portion of the digit's microseconds (e.g. 154 in the last example)

Tested on stable: Flutter 3.3.1 Dart 2.18.0.

update: conversion isn't lossy on platform other than web and DartPad.