//class object and constructor
//beginner level constructor
void main(){
  //creating a object called 'jenny'
  Human jenny = Human(15);
  //now accessing method talk
  jenny.talk('hello world');
  print('i am ${jenny.height} years old');

  //operation on advance constructor
  Human2 sam = Human2(height:10,weight:20);
  print('his height is ${sam.height} and ${sam.weight}');
}

class Human{
  //properties
  double height;
  int age=1;

  //constructor
  Human(double startingHeight){
    height = startingHeight;
  }

  //methods
  void talk(String speak){
    print(speak);
  }

}

// advance level of constructor
class Human2{
  double height;
  double weight;

  //creating a constructor
  Human2({this.height,this.weight});
}