Go Interface example - print area of shapes

main.go

package main

import (
	"fmt"
	"reflect"
)

func main() {
	r := Rectangle{length:5, width:10}
	printArea(&r)
	
	s := Square{length:5, width:5}
	printArea(&s)
}

type Shape interface {
	area() int
}

type Rectangle struct {
	length int
	width int
}

type Square struct{
	length int
	width int
}

func (rect *Rectangle) area() int{
	return rect.length * rect.width
}

func (square *Square) area() int{
	return square.length * square.width
}


func printArea(shape Shape){
	fmt.Printf("Area of %s is %d \n", reflect.TypeOf(shape) , shape.area())
}