## Person
### Instructions
Create a `class` named `Person` .
Its attributes:
- `name` : `string`
- `surname` : `string`
- `cityOfOrigin` : `string`
- `age` : `int`
- `height` : `int`
Constructor:
- `name` : `required`
- `cityOfOrigin` : `required`
- `age` : `required`
- `height` : `required`
- `surname` : `optional`
### Object Oriented Programming
Dart supports object oriented programming, and it features heavily in Flutter. Classes have 2 main concepts.
- Attributes: store data about the instance of a class.
- Methods: are func functions, which can use class attributes for various manipulations.
Here is an example of a class in Dart. `Point` is the name of the class, while `x` and `y` are attributes:
```dart
class Point {
double x = 0; // attribute initialized to 0
double y = 0; // attribute initialized to 0
}
```
What if you want to initiate a `Point` with different `x` and `y` ? We use constructors to solve this problem. A constructor is a function which specifies how to instantiate an instance of a class, from a set of given parameters.
```dart
class Point {
// Attributes
double x = 0;
double y = 0;
// Constructor
Point(double x, double y) {
// Initializing attributes
this.y = y;
this.x = x;
}
}
```
In Dart we can also use **constructor declaration** to save a few lines of code.
```dart
class Point {
double x;
double y;
Point(this.x, this.y);
}
```
Now let's instantiate two objects of class `Point` :
```dart
var p1 = Point(5, 4);
var p2 = Point(8, 3);
```
Suppose we want to know the distance between these 2 points? We can do that by declaring a method, and passing one of the objects as a parameter:
```dart
import 'dart:math';
class Point {
double x;
double y;
Point(this.x, this.y);
// Method
double distanceTo(Point end) {
return sqrt(pow((end.x - this.x), 2) + pow((end.y - this.y), 2));
}
}
void main() {
var p1 = Point(5, 4);
var p2 = Point(8, 3);
print(p1.distanceTo(p2));
}
```
Check out the [class ](https://dart.dev/guides/language/language-tour#classes ) section of the dart language tutorial.
