58 lines
705 B
Go
58 lines
705 B
Go
|
package main
|
||
|
|
|
||
|
|
// interfaces example
|
||
|
|
|
||
|
|
import (
|
||
|
|
"fmt"
|
||
|
|
"math"
|
||
|
|
)
|
||
|
|
|
||
|
|
type Shape interface {
|
||
|
|
area() float64
|
||
|
|
perim() float64
|
||
|
|
}
|
||
|
|
|
||
|
|
type Circle struct {
|
||
|
|
r float64
|
||
|
|
}
|
||
|
|
|
||
|
|
func (c Circle) area() float64 {
|
||
|
|
return c.r * c.r * math.Pi
|
||
|
|
}
|
||
|
|
|
||
|
|
func (c Circle) perim() float64 {
|
||
|
|
return 2 * math.Pi * c.r
|
||
|
|
}
|
||
|
|
|
||
|
|
type Rect struct {
|
||
|
|
a float64
|
||
|
|
b float64
|
||
|
|
}
|
||
|
|
|
||
|
|
func (r Rect) area() float64 {
|
||
|
|
return r.a * r.b
|
||
|
|
}
|
||
|
|
|
||
|
|
func (r Rect) perim() float64 {
|
||
|
|
return (r.a + r.b) * 2.0
|
||
|
|
}
|
||
|
|
|
||
|
|
func main() {
|
||
|
|
c := Circle{
|
||
|
|
r: 5.0,
|
||
|
|
}
|
||
|
|
|
||
|
|
r := Rect{
|
||
|
|
a: 2.0,
|
||
|
|
b: 3.0,
|
||
|
|
}
|
||
|
|
|
||
|
|
showShape("Circle", c)
|
||
|
|
showShape("Rect", r)
|
||
|
|
}
|
||
|
|
|
||
|
|
func showShape(name string, s Shape) {
|
||
|
|
fmt.Printf("%v area %.2f\n", name, s.area())
|
||
|
|
fmt.Printf("%v area %.2f\n\n", name, s.perim())
|
||
|
|
}
|