A basic dart file to show most of the basics of the dartlang.

commandLine1.dart

void main() {
  //print("Hello, World!");
  num a=24;
  printNumber(a);
  var b=45;//declaring without a type declaration, but you can see assigning a string to this will throw compile time error
  printNumber(b);
  Joe j=new Joe();
  //print(j.age);//can not access private var
  print('j is of ${j.userAge}');//getter
  j.userAge=30;//setter
  print('j is of ${j.userAge}');//getter
  print('j is from city ${j.fromCity}');
  Person p1=new Person.inCity('Pune');
  print('p1 is from ${p1.fromCity}');
  Person p2=new Person();
  print('p2 is from ${p2.fromCity}');
}

void printNumber(num aNumber){
  print('The number is $aNumber');
}

class Person {
  int _age=20;//private variable
  String fromCity='Unknown';//public variable
  //default constructor
  Person(){
    print('Person : Default constructor');
  }
  //named constructor
  Person.inCity(String nameOfCity){
    this.fromCity=nameOfCity;
  }
  //getter
  int get userAge{
    print('Person : getter : ');
    return this._age;
  }
  void set userAge(int n){
    print('Person : setter : ');
    this._age=n;
  }
}
//extending the class
class Joe extends Person{
  Joe(){
    print('Joe : Default constructor');
  }
}