Merge pull request #2778 from arcAman07/master

Calculating area of shapes using Interfaces in go.

Program's_Contributed_By_Contributors/Golang Programs/areaFigure.go

@@ -0,0 +1,37 @@
+package main
+import (
+	"fmt"
+	"math"
+)
+type circle struct {
+	radius float64
+}
+type square struct {
+	side float64
+}
+type rectangle struct {
+	length, width float64
+}
+func (c circle) area() float64 {
+	return math.Pi * c.radius * c.radius
+}
+func (s square) area() float64 {
+	return s.side * s.side
+}
+func (r rectangle) area() float64 {
+	return r.length * r.width
+}
+type shape interface {
+	area() float64
+}
+func info(s shape) {
+	fmt.Println("Area:", s.area())
+}
+func main() {
+	c := circle{radius: 5}
+	s := square{side: 5}
+	r := rectangle{length: 5, width: 10}
+	info(c)
+	info(s)
+	info(r)
+}