flutter pub add decimal根據套件公開資料產生的選型評估，僅供參考。
decimal 套件在 Dart 中提供精確的十進位算術，可準確處理十進位數字，避免浮點運算常見的精度損失。它支援精確的十進位表示與算術運算，非常適合用於財務計算及其他需要高準確度的場景。此套件相容於所有主要平台，包含行動裝置、網頁與桌面端。它提供一個乾淨的 API，可用於建立、操作與格式化十進位值，並完全控制四捨五入模式與尺度。
以下為關聯原始碼儲存庫的 README 原文快照，最新內容請造訪原始碼儲存庫。
This project enable to make computations on decimal numbers without losing precision like double operations.
For instance :
// with double
print(0.2 + 0.1); // displays 0.30000000000000004
// with decimal
print(Decimal.parse('0.2') + Decimal.parse('0.1')); // displays 0.3
To use this library in your code :
pubspec.yaml :dependencies:
decimal:
dart code :import 'package:decimal/decimal.dart';
Decimal.parse('1.23').Hint : To make your code shorter you can define a shortcut for Decimal.parse :
final d = (String s) => Decimal.parse(s);
d('0.2') + d('0.1'); // => 0.3
You can use the intl package to format decimal
with DecimalFormat from the package:decimal/intl.dart library:
import 'package:decimal/decimal.dart';
import 'package:decimal/intl.dart';
main() {
var value = Decimal.parse('1234.56');
var formatter = DecimalFormatter(NumberFormat.decimalPattern('en-US'));
print(formatter.format(value));
}
Tip: you can define an extension to make it more fluent:
extension on Decimal {
String formatWith(NumberFormat formatter) => formatter.format(DecimalIntl(this));
}
main() {
var value = Decimal.parse('1234.56');
var formatter = DecimalFormatter(NumberFormat.decimalPattern('en-US'));
print(value.formatWith(formatter));
}
WARNING: For now (2024.05.30) intl doesn't work with NumberFormat.maximumFractionDigits greater than 15 on web plateform and 18 otherwise.
You can use the NumberFormat from intl package to parse formatted decimals
var currencyFormatter = DecimalFormatter(NumberFormat.simpleCurrency(name: 'USD'));
currencyFormatter.parse('\$3.14'); // => 3.14
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