那些你不知道的Dart细节之内置类型（二）

int i = 1; //整数值
  double d = 1.0; //double  64-bit (双精度) 浮点数
  int bitLength = i.bitLength;
  print('bitLength: ${bitLength}'); //bitLength判断int值需要多少bit位
  double maxFinite = double.maxFinite;
  print('maxFinite: ${maxFinite}'); //maxFinitedouble的最大值
  //int和double都是num的子类
  num n1 = 1;
  num n2 = 1.0;
  //支持十进制、十六进制
  int i1 = 0xfff;
  //科学计数法
  double d1 = 1.2e2; //120.0
  //转换
  //String->int
  int i2 = int.parse('1');
  double d2 = 1; //当double的值为int值时，int自动转成double
  print('d2: ${d2}');
//  int i2 = int.tryParse('1.0');//返回null

main(){
  String a = 'zhujiang';
  String b = "zhujiang";
}

String c = "dd"
    "sssdffg"
  "vftgt";
  String d = '''ssss
  fffffffgg
  grrrr''';

String e = '''ssss
  fff\nffffgg
  grrrr''';
  String f = r'''ssss
  fff\nffffgg
  grrrr''';
  print(e);
  print(f);

lib/2-type.dart: Warning: Interpreting this as package URI, 'package:darttest/2-type.dart'.
ssss
  fff
ffffgg
  grrrr
ssss
  fff\nffffgg
  grrrr

print("object:$c");

StringBuffer stringBuffer = StringBuffer();
  stringBuffer..write("sss")..write("ssss");

print(List)

//常用方法 增删改查，排序，洗牌，复制子列表
  var list4 = [];
  //增
  list4.add(1);
  print('add 1 :${list4}');
  //删
  list4.remove(5);
  print('remove 5 :${list4}');
  list4.removeAt(2);
  print('remove at 0 :${list4}');
  //改
  list4[4] = 5;
  print('update list4[4] to 5 :$list4}');
  //range
  list4.fillRange(0, 3, 9);
  print('fillRange update list4[0]-list4[2] to 9 :$list4}');
  Iterable getRange = list4.getRange(0, 3);
  print('getRange list4[0]-list4[2] :$getRange}');
  //查
  var contains = list4.contains(5);
  print('list4 contains 5 :${contains}');
  var indexOf = list4.indexOf(1);
  print('list4 indexOf 1 :${indexOf}');
  int indexWhere = list4.indexWhere((test) => test == 5);
  print('list4 indexWhere 5 :${indexWhere}');
  //排序
  list4.sort();
  print('list4 sort :${list4}');
  //洗牌
  list4.shuffle();
  print('list4 shuffle :${list4}');
  //复制子列表
  var list5 = list4.sublist(1);
  print('sublist(1) list5 :${list5}');
  //操作符
  var list6 = [8, 9];
  print('list6 :${list6}');
  var list7 = list5 + list6;
  print('list5 + list6 :${list7}');

set1.difference(set2):返回set1集合里有但set2里没有的元素集合
set1.intersection(set2)：返回set1和set2的交集
set1.union(set2)：返回set1和set2的并集
set1.retainAll()：set1只保留某些元素(要保留的元素要在原set中存在）
这几个方法非常好用，简单写一下伪代码大家看一下吧：
  var difference12 = set1.difference(set2);
  var difference21 = set2.difference(set1);
  print('set1 difference set2 :${difference12}'); //返回set1集合里有但set2里没有的元素集合
  print('set2 difference set1 :${difference21}'); //返回set2集合里有但set1里没有的元素集合
  var intersection = set1.intersection(set2);
  print('set1 set2交集 :${intersection}'); //返回set1和set2的交集
  var union = set1.union(set2);
  print('set1 set2并集 :${union}'); //返回set1和set2的并集
  set2.retainAll(['aa', 'flutter']); //只保留(要保留的元素要在原set中存在）
  print('set2只保留aa flutter :${set2}');

Runes runes = new Runes('\u{1f605} \u6211‘);
  var str1 = String.fromCharCodes(runes);  
  print(str1);

😅 我
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