Dart数据类型详解 int 、double、String、bool、List、Map

 //可以用is 来判断类型
 void main() {
  //字符串类型,可以用单引号，也可以用双引号,也可以用三个单引号或者三个双引号
  var str = '你好Dart';
  var s = "你好Dart";
  var st = '''
  helle dart 
  hello world''';
  
  //换行会直接报错
  // var str2 = "helle dart 
  // hello world";
  // print(str);
  // print(s);
  // print(str1);


  //字符串拼接
  String str1 = "你好";
  String str2 = "Dart";
  print(str1+str2);
  print(str1+" "+str2);
  print("$str1$str2");


  //int 类型
  int a = 1;
  print(a);

  //double 类型
  double b = 23.9;
  print(b);

  //bool 类型

  bool flag = true;
  print(flag);

  //数组、集合

  var list1 = ["1","2","3"];
  print(list1);
  print(list1.length);
  print(list1[0]);


  var list2 = new List();
  list2.add("a");
  list2.add("b");
  list2.add("c");

  print(list2);
  print(list2.length);


  var list3 = new List<String>();
  list3.add("张三");
  list3.add("李四");
  print(list3);


  //Map(字典)
  var persons = {"name":"张三","age":25};
  print(persons);
  print(persons["name"]);
  print(persons["age"]);

  var person = new Map();
  person["name"] = "李四";
  person["age"] = 29;
  person["works"] = ["作家","医生"];
  print(person);
 }