Dart - List (index, last, length, forEach, fold, takeWhile, subList, toList, addAll, growable, map)

Dart: Up and Running
(O'Reilly Media)
Kathy Walrath Seth Ladd (著)
[Kindle版]
このブログでの感想

開発環境

• OS X Mavericks - Apple (OS)
• Dart Editor (開発環境)
• Dartium | Dart/ Structured web apps (ブラウザ, Dart VM 用 (Chromium with the Dart VM))
• Safari (ブラウザ, JavaScript 用)
• Dart (プログラミング言語)

初めてのコンピュータサイエンス(Jennifer Campbell、Paul Gries、Jason Montojo、Greg Wilson(著)長尾 高弘(翻訳))の4章(モジュール)、4.8(練習問題)、1から13をDartで解いてみる。

その他参考書籍

• What is Dart? [Kindle版] (O'Reilly Media) Kathy Walrath Seth Ladd (著) このブログでの感想

4.8(練習問題)、1から13.

コード

sample.dart

import 'dart:html';

void main() {
  query("#run_dart").onClick.listen((MouseEvent event){
    var start = new DateTime.now().millisecondsSinceEpoch,
        n = 30,
        result = run(event);
    query('#pre0').text = window.navigator.userAgent + '\n' +
        '${(new DateTime.now().millisecondsSinceEpoch - start) / 1000}秒\n' +
        result;
  });
  query('#clear').onClick.listen((MouseEvent event){
    query('#pre0').text = '';
  });
}
String run(MouseEvent event){
  var result = '',
      alkaline_earth_metals = [4, 12, 20, 38, 56, 88],
      country_populations = [1295, 23, 7, 3, 47, 21],
      temps = [25.2, 16.8, 31.4, 23.9, 28, 22.5, 19.6],
      cool_temps,
      warm_temps,
      temps_in_celsius,
      temps_in_fahrenheit;
  result += '1. ${alkaline_earth_metals}\n';
  result += '2.\nラジウムの原子番号: ${alkaline_earth_metals[5]} ' +
      '${alkaline_earth_metals.last}\n';
  result += '3.リストの長さ ${alkaline_earth_metals.length}\n';
  alkaline_earth_metals.sort((num a, num b){
    return a - b;
  });
  result += '4. 最も高い原子番号: ${alkaline_earth_metals.last}\n';
  result += '6.1行にお1つずつ表示\n';
  alkaline_earth_metals.forEach((e){
    result += '${e}\n';
  });
  result += '7. 1行に全て表示\n';
  alkaline_earth_metals.forEach((e){
    result += '${e} ';
  });
  result += '\n';
  result += '8. ${country_populations}\n';
  result += '合計: ${country_populations.fold(
      0, (prev, elem) => prev + elem)}\n';
  result += '9. ${temps}\n';
  temps.sort();
  result += '10. ソート ${temps}\n';
  cool_temps = temps.takeWhile((e) => e < 20);
  warm_temps = temps.sublist(cool_temps.length);
  result += '11.\ncool_temps: ${cool_temps.toList()}\nwarm_temps: ${warm_temps}\n';
  temps_in_celsius = [];
  temps_in_celsius.addAll(cool_temps);
  temps_in_celsius.addAll(warm_temps);
  result += '12. 摂氏: ${temps_in_celsius}\n';
  temps_in_fahrenheit = temps_in_celsius.map((e) => e * 9 / 5 + 32);
  result += '13. 華氏に変換: ${temps_in_fahrenheit.toList()}';
  return result;
}