more

32-fields.go

@@ -0,0 +1,15 @@
+package main
+
+import "fmt"
+
+type Circle struct {
+	x, y, r int
+}
+
+func main() {
+	c := Circle{x: 1, y: 2, r: 5}
+	fmt.Println(c.x, c.y, c.r)
+	c.x = 10
+	c.y = 5
+	fmt.Println(c.x, c.y, c.r)
+}

33-methods.go

@@ -0,0 +1,35 @@
+package main
+
+import "fmt"
+import "math"
+
+type Circle struct {
+    x, y, r float64
+}
+
+func (c *Circle) area() float64 {
+    return math.Pi * c.r*c.r
+}
+
+type Rectangle struct {
+    x1, y1, x2, y2 float64
+}
+
+func distance(x1, y1, x2, y2 float64) float64 {
+    a := x2 - x1
+    b := y2 - y1
+    return math.Sqrt(a*a + b*b)
+}
+
+func (r *Rectangle) area() float64 {
+    l := distance(r.x1, r.y1, r.x1, r.y2)
+    w := distance(r.x1, r.y1, r.x2, r.y1)
+    return l * w
+}
+
+func main() {
+	circle := Circle{x: 0, y: 3, r: 5}
+	fmt.Println(circle.area())
+	rectangle := Rectangle {x1: 3, x2: 10, y1: 5, y2: 7}
+	fmt.Println(rectangle.area())
+}